I thought it would be neat for us to exchange information about vitamins, minerals and supplements.

To all posters/readers understand:

All material provided within this thread is for informational and educational purposes only, and in no way is any of the content to be construed as medical advice or instruction. No action should be taken solely on the contents.

The information provided is believed to be accurate based on the best judgment of the author(s) but the reader is responsible for consulting with their own health professional on any matters raised within.

Seek the advice of your physician before taking supplements of any kind. Consult your physician or a qualified health professional on any matters regarding your health and well being or on any opinions expressed.

www.medicinenet.com/script/main/art.asp?articlekey=9487

Viewer Question:
What is cholesterol-lowering niacin or nitcotinic acid?

Doctor's Response:
Nicotinic acid or niacin, one of the water-soluble B vitamins, improves all lipoproteins when given in doses well above the vitamin requirement. Nicotinic acid lowers the total cholesterol, "bad" LDL-cholesterol, and triglyceride levels, while raising the "good" HDL-cholesterol level.

There are two types of nicotinic acid: immediate release and timed release. Most experts recommend starting with the immediate-release form; discuss with your doctor which type is best for you.

Nicotinic acid is inexpensive and widely accessible to patients without a prescription but must not be used for cholesterol lowering without the monitoring of a physician because of the potential side effects. (Nicotinamide, another form of the vitamin niacin, does not lower cholesterol levels and should not be used in the place of nicotinic acid.)

All patients taking nicotinic acid to lower serum cholesterol should be closely monitored by their doctor to avoid complications from this medication. Self-medication with nicotinic acid should definitely be avoided because of the possibility of missing a serious side effect if not under a doctor's care.

Patients on nicotinic acid are usually started on low daily doses and gradually increased to an average daily dose of 1.5 to 3 grams per day.

Nicotinic acid reduces LDL-cholesterol levels by 10 to 20 percent, reduces triglycerides by 20 to 50 percent, and raises HDL-cholesterol by 15 to 35 percent.

A common and troublesome side effect of nicotinic acid is flushing or hot flashes, which are the result of the widening of blood vessels. Most patients develop a tolerance to flushing, and in some patients, it can be decreased by taking the drug during or after meals or by the use of aspirin or other similar medications prescribed by your doctor. The effect of high blood pressure medicines may also be increased while you are on niacin. If you are taking high blood pressure medication, it is important to set up a blood pressure monitoring system while you are getting used to your new niacin regimen. A variety of gastrointestinal symptoms including nausea, indigestion, gas, vomiting, diarrhea, and the activation of peptic ulcers have been seen with the use of nicotinic acid.

Three other major adverse effects include liver problems, gout, and high blood sugar. Risk of these three complications increases as the dose of nicotinic acid is increased. Your doctor will probably not prescribe this medicine for you if you have diabetes, because of the effect on your blood sugar.

Thank you for your question.

Last Editorial Review: 12/30/2004

I have been wondering why my dad has been getting blood clots in his legs, they are close to the skin surface and travel upward and then dissipate after he takes a greater than usual amount of B-Complex. Thing is, he's been using aspirin all his life, his blood should be very thin. I came across an article containing information about Homocysteine and wondered if it might be the culprit.

healthetimes.com/2010/03/01/homocysteine-and-your-heart/

Homocysteine and Your Heart

Posted on 01. Mar, 2010 by Jack Challem in Heart Health

Homocysteine. Consider it the “new cholesterol”—and the real cause of heart disease, stroke, and peripheral artery disease. If the term strikes you as being strange, don’t worry. It will soon be a household word, just like cholesterol. Why homocysteine? And what’s happening with the idea that cholesterol causes cardiovascular diseases? Lowering homocysteine levels may be the key to lowering the risk of many cardiovascular diseases—and the treatment may be as easy as supplementing with B-complex vitamins.
The Problem with Cholesterol

Ever since researchers began to see cholesterol as a cause of coronary heart disease, they’ve been plagued with disturbing inconsistencies. For example, while cholesterol is found in the fatty deposits that clog arteries, 80 percent of heart attacks occur in men with normal cholesterol levels.

Furthermore, cholesterol is essential for health, and the body makes most of the cholesterol found in the blood. It functions as an antioxidant and serves as a building block for steroid hormones. It’s even needed to transport vitamin E, coenzyme Q10, and other fat-soluble nutrients through the blood.

To resolve these and other problems, researchers have emphasized so-called good and bad forms of cholesterol, healthy and unhealthy ratios between the different forms of cholesterol, and, most recently, oxidized and nonoxidized cholesterol. In fact, cholesterol has gotten so confusing that many doctors now discount it as a cause of cardiovascular disease.

Instead, they’re shifting their attention to homocysteine as a principal cause of cardiovascular diseases. By some estimates, 40 percent of heart attacks and strokes in the United States may be the result of elevated levels of homocysteine in the blood.
What Is Homocysteine?

Like cholesterol, the body makes homocysteine. It serves a necessary function in the body, after which it’s normally broken down. When left intact, it enters the bloodstream and begins attacking blood vessel walls, laying the foundation for coronary heart disease, stroke, and other cardiovascular diseases.

Protein, and particularly the essential amino acid methionine (found in meat), is the indirect source of homocysteine. When the body digests and metabolizes methionine, it produces homocysteine before either recycling it back to methionine or creating the final breakdown product, cystathionine.

There are many circumstances in which homocysteine becomes a long-lived, potentially deadly byproduct of protein metabolism. For example, an inadequate supply of key B vitamins “freezes” homocysteine metabolism before converted to cystathionine. When this happens, abnormally high levels of homocysteine build up in the bloodstream and damage blood vessels. When the blood vessels feeding the heart are damaged, coronary artery disease develops. When the blood vessels that nourish the brain are affected, stroke is the likely outcome. If the blood vessels of the hands or legs are affected, peripheral artery disease is the likely consequence.
B Vitamins

There aren’t any high-priced, exotic drugs to treat homocysteine. The cure, in fact, is remarkably simple and cheap. Homocysteine levels can be reduced by taking one or all of these nutrients:

• folic acid
• vitamin B6
• vitamin B12
• choline
• betaine.

In an inverse relationship, the increase of one event causes another event to decrease—like the motion of a seesaw. For example, with homocysteine and the B vitamins, increasing intake of B vitamins lowers homocysteine levels. The reverse is also true: homocysteine levels increase when B vitamin intake is low.

Nutritional surveys confirm that deficiencies of the B vitamins are prevalent in the United States. In addition, research shows that if one B vitamin is missing from the diet, chances are good that most, if not all, of the others will also be in short supply. These widespread B-vitamin deficiencies result in dangerously high homocysteine levels. However, since the majority of doctors do not assess homocysteine levels in their patients, the best offense to prevent cardiovascular diseases appears to be a good defense—supplementing with B vitamins.
Busy Bs

Folic Acid protects the body from unusually high homocysteine levels by assisting another enzyme in converting homocysteine back to the amino acid methionine. If the body does not have adequate amounts of folic acid, homocysteine begins to accumulate. As levels of homocysteine rise, blood vessels are injured, arteriosclerosis accelerates, and the risk of heart attack and stroke escalates. In a recent study, 818 men and women aged 50 to 70 with elevated homocysteine levels took 800 micrograms of folic acid or a placebo every day for three years. At the end of the study, people taking folic acid supplements experienced a 26 percent decrease (on average) in homocysteine levels.

Folic acid requirements increase in several situations, such as during pregnancy and lactation, during illness, and with the use of some drugs (including oral contraceptives, several cancer treatments, and alcohol). In addition, smokers have lower folic acid levels than nonsmokers and may require a higher intake to maintain normal status of this important B vitamin.

Vitamin B6 is involved in the metabolism of proteins and carbohydrates. Low levels allow homocysteine to increase and initiate the atherosclerotic process. Unfortunately, low levels of vitamin B6 appear to be the rule rather than the exception. Symptoms of vitamin B6 deficiency are vague, but include weakness, mental confusion, anemia, and insomnia. Oral contraceptives increase vitamin B6 requirements.

Good food sources of this essential vitamin include beans, nuts, bananas, cabbage, cauliflower, potatoes, and whole-grain cereals and breads. Foods made with white flour are poor sources of this vitamin because “enrichment” does not replace the vitamin B6 lost in the refinement process.

Vitamin B12 is also essential during the metabolism of protein, fat, and carbohydrates. As with folic acid and vitamin B6, vitamin B12 must be present to rid the body of harmful amounts of homocysteine. The deficiency disease most associated with vitamin B12 is pernicious anemia. Other symptoms of vitamin B12 deficiency include disorientation, numbness, confusion, agitation, dizziness, hallucinations, impaired immunity, nausea, and vomiting.

Vitamin B12 is only found in foods of animal origin, such as meat, fish, and dairy products. Deficiencies are more common during mid- to late life and in strict vegetarians (who exclude all animal products). As many as 15 percent of the elderly may have vitamin B12 deficiencies.

Choline is another essential B vitamin. It’s a building block for phospholipids, fats needed in cell membranes. Choline also contributes to the production of the neurotransmitter acetylcholine, which is important in brain function and memory. Choline was discovered early on to reduce homocysteine levels and the risk of cardiovascular diseases.

To produce choline, the body must have adequate amounts of folic acid. Often, deficiencies of folic acid and choline go hand in hand. Good food sources of choline include eggs, organ meats, lean meat, brewer’s yeast, wheat germ, soybeans, and peanuts.

Betaine is another beneficial substance found in some foods, supplements, and is produced by the body. Like the B vitamins, large supplemental doses of betaine limit the unhealthy buildup of homocysteine. While betaine is not usually the first choice in treating elevated homocysteine levels, it often plays an important role in difficult-to-treat cases. Several studies have reported that betaine supplements successfully lower homocysteine in cases in which vitamin B6 and folic acid failed.
Why Take a Supplement?

Folic acid, vitamin B6, vitamin B12, choline, and betaine have all been shown to reduce homocysteine levels. Yet it would be difficult to get enough of these important nutrients from food sources alone. For example, one would have to eat 10 cups of broccoli or 11 bananas every day to consume the level of folic acid or vitamin B6 necessary to reduce elevated homocysteine levels. Supplements are an easy and convenient option for anyone concerned with preventing or treating cardiovascular diseases.

A high-potency daily multivitamin/mineral formula will provide the basic amounts of the B vitamins needed to prevent homocysteine levels from rising. Separate supplements of folic acid, vitamin B6, and vitamin B12 may be required to lower very high or resistant homocysteine levels. However, supplement with all three to prevent possible imbalances from high doses of just one B vitamin.

Although many of the causes and steps in the progression of cardiovascular diseases remain unclear to scientists, one thing is clear—B vitamins lower homocysteine levels, which in turn can save tens of thousands of lives—maybe even yours. Talk to your healthcare provider today about the simple tests to determine your levels of B vitamins and homocysteine.

About the author:

Jack Challem, The Nutrition Reporter™, is a personal nutrition coach and bestselling author based in Tucson, Arizona. He is one of America's most trusted nutrition and health writers, with 30 years of experience writing about research and clinical experience on nutrition, vitamins, minerals, and herbs. He is the author of The Food-Mood Solution, Feed Your Genes Right, The Inflammation Syndrome, and the lead author of Syndrome X: The Complete Nutritional Program to Prevent and Reverse Insulin Resistance. Jack is also the series editor for the 50-volume User's Guide series of health paperback books (Basic Health Publications). He writes The Nutrition Reporter™ newsletter. Jack is a frequent speaker at nutritional medicine conferences and to consumer health groups. www.nutritionreporter.com

CoQ10

www.preventive-health-guide.com/coq10.html

What are the results of deficiency in CoQ10?

Firstly, What is CoQ10?

Coenzyme Q10 (or CoQ10) is a natural chemical compound that we make in our bodies and consume in our diets, primarily from oily fish, organ meats such as liver, and whole grains.

It resides in the energy-producing part of cells and is involved with producing a key molecule known as adenosine-5-triphosphate (or ATP).

ATP is a cell's major energy source and it contributes to several important biological processes, such as the production of protein, and muscle contraction.

Why is CoQ10 important?

CoQ10 has the potential to vastly improve human health. It can help you combat fatigue, for example, as well as obesity, and a weak immune system (particularly for those with HIV, other viruses, and yeast infections).

It helps boost athletic performance (CoQ10 levels are low in people who exercise excessively), and it improves exercise tolerance in people with muscular dystrophy.

It also prevents toxin overload, and swollen gums (those with periodontal disease tend to have low levels of CoQ10 in their gums). Early studies show it may also increase sperm motility, leading to enhanced fertility. It’s all in a day’s work for CoQ10!

What's the importance of COQ10 for heart disease?

The American Chemical Society's most prestigious honour, the Priestley Medal, was awarded to Karl Folkers, Ph.D., for his landmark Coenzyme Q10 (CoQ10) research. That’s because Folkers found that in addition to the benefits listed above, CoQ10’s most valuable role may lie in fighting heart disease.

In fact, he says he found the blood levels of CoQ10 to be significantly lower in heart-disease patients than in those who were disease free, and he discovered that 70 percent of his heart patients with congestive heart failure benefited from taking CoQ10.

Eminent heart surgeon Denton Cooley, M.D., agrees. He says that in heart biopsies, he found 75 percent of his cardiac patients had varying, but significant, deficiencies of CoQ10. Reports by over a hundred Japanese cardiac specialists who gave CoQ10 to thousands of patients with heart problems for nearly ten years also seemed to support these findings.

Additional benefits of CoQ10

Not only that, but several studies with small numbers of people suggest that CoQ10 may lower blood pressure after a few weeks, and it might help to prevent some of the heart damage caused by chemotherapy.

Introducing CoQ10 before heart surgery may reduce the damage caused by free radicals and oxidative damage, as well as lowering the incidence of irregular heart beat, and strengthening heart function during recovery.

Interesting effects on cholesterol lowering drugs

CoQ10 levels tend to be lower in people with a high cholesterol count, compared with healthy individuals of the same age.

What’s more, certain cholesterol-lowering drugs (statins such as cerivastatin, atorvastatin, pravastatin simvastatin and lovastatin) seem to reduce the natural levels of CoQ10 in the body.

Taking CoQ10 supplements can correct the deficiency caused by statins, without changing the medication's positive effects on cholesterol levels.

As a result of its beneficial effects on one of the body’s most important organs, Folkers calls CoQ10 "a natural and essential co-factor in the heart."

CoQ10 and diabetes

Of course, managing cholesterol levels, helping the circulatory system, blood sugar levels and heart health is particularly important for diabetics, and CoQ10 supplements may be a help to them.

Despite concern that CoQ10 may cause a sudden drop in blood sugar, two recent studies of people with diabetes given CoQ10 twice a day showed they experienced no hypoglycemic response. If you’re diabetic, talk to your doctor about how you can safely take CoQ10.

CoQ10 for Alzheimers and cancer

Now, scientists are hoping its effects on the heart, blood systems, and tissue toxicity means CoQ10 can soon be used as part of a treatment program for Alzheimer's disease, and for recovery from stroke. They’re also hopeful about the possibility of using it as part of a treatment regimen for women with breast cancer (together with conventional treatment and a nutrional program involving high levels of other antioxidants and fatty acids).

How does CoQ10 perform all these roles?

So how does it do it? Researchers think it may all be possible on account of CoQ10’s ability to inhibit blood clot formation, improve energy production in cells, and act as an antioxidant.

Antioxidants are substances that hunt for free radicals and escort them out of the body, which prevents the free radicals causing oxidative damage to cell membranes and DNA when they accumulate in the tissues and blood as a result of pollution, UV light, cigarette smoking, and as a by-product of normal metabolic processes.

Free radicals cause us to age more quickly, and they contribute to a number of health problems including heart disease and cancer.

Helping the fight agaist free radicals

Antioxidants such as CoQ10 can neutralize free radicals and may reduce or even help prevent some of the damage they cause.

CoQ10 may have found its perfect partner in another potent antioxidant: vitamin E. Together they are the principle fat-soluable antioxidants in cells, and CoQ10 may help vitamin E act more effectively in the body.

Another friend of CoQ10 is the spectacular antioxidant dihydrolipoic acid (DHLA). It’s unique in its ability to zap every known free radical that occurs in living tissue; it’s also readily absorbed and has a very low toxicity.

Its talents make it a valuable resource in combating the free radical damage associated with Alzheimer’s disease, for example, as well as Parkinson's disease, and other degenerative brain conditions. CoQ10 may not work as effectively alone, so to take advantage of its enormously helpful health benefits, be sure to combine your good quality supplements with a healthy diet, stress reduction techniques, and responsible levels of exercise. Enjoy!

DHA

healthetimes.com/2011/04/06/dha-critical-at-any-age/

DHA: Critical at Any Age

Posted on 06. Apr, 2011 by Robert Abel, Jr., MD in Nutrition

As a society, we are starving our children. Yet this newest generation to the planet is so obese that children are developing Type 2 diabetes in unprecedented numbers at younger and younger ages. The fast, tasty, easy processed foods that bedeck our glittering food emporia are mostly empty calories that fatten our children while robbing their brains, nervous systems, eyes, and very spirits of the nourishment they need to flourish. And yet, in our fat-phobic obsession to be thin and have slender children, we have labeled all fats as the enemy.

Necessary Fats

We need to be far more selective before we banish one-third of all naturally occurring nourishment. Some fats are so important, they are said to be “essential,”or essential fatty acids (EFAs). One of these essential fatty acids is DHA, or docosahexaenoic acid.

Healthy Mothers, Healthier Babies

DHA is usually associated with the central nervous system, and taking DHA is especially important in the growth of the brain and in learning. The most active period for the development of the central nervous system is while the baby is still growing inside the mother.

During the first trimester of pregnancy, especially in the first five weeks, the nervous system and the eyes of the fetus begin to develop. Obviously, this is a very critical time and deficiency of fatty acids during this period can cause a range of very serious problems. Then again, during the last trimester of pregnancy, the brain doubles in size. The fetus is undergoing the “finishing touches” and growing a lot bigger. Approximately 80 percent of the growth of the fetus during the final trimester centers on building the brain. During the last critical months, the mother’s body transfers to the fetus the nutrient materials that become the foundation of the baby’s brain and nervous system. The transfer of DHA to the baby causes the mother’s DHA level to decrease. This is the only time in the human lifecycle that the body doesn’t retain all of the DHA taken in from the diet. Numerous studies show that the levels of EFAs in the diet and therefore in the milk of many American mothers is below the recommended amount to support fetal and infant requirements—to say nothing of their own.

Mother’s Milk and Baby’s Brain

In the U.S., more infants are given formula than in many other countries. Great care has been taken to ensure that formulas contain the optimal amounts of vitamins, minerals, carbohydrates, proteins, and fats for the infant. Still, formula is not, as yet, identical to mother’s milk, and attempting to ascertain the differences has been the focus of many studies.

The differences appear when one compares the long- term achievement, behavior, or performance on IQ tests of individuals who were breast-fed as infants to those who were formula-fed. In one analysis, children who were breast-fed scored on average three to five points higher on IQ tests than children who were formula-fed.

Measurements of vision and the progression of growth, orientation, motor skills, and learning during infancy indicate that even though formula-fed babies grow bigger and more quickly than breast-fed babies, their developmental progression is slowed. Studies show that formula- fed babies at ages two to three years old complete an eye chart (with pictures of animals instead of letters) one line higher (larger pictures equal poorer vision), on average, than breast-fed babies at the same age. Clinical studies show that if DHA and ARA (arachadonic acid, an omega-6 fat) are added to standard formulas, the babies’ visual development returns to normal, as compared with the vision of the breast-fed infants.

Learning and Behavior

Fatty acids also have a close relationship with cognitive function, motor and sensory skills, and emotional health. ADHD affects an estimated 5 percent of the juvenile population. Of this number, more boys than girls are effected. The disorder is generally characterized by inattention, impulsiveness, and hyperactivity, although the severity of the symptoms varies among individuals.
ADHD is less often seen in infants who were breast-fed or given supplements of DHA. Researchers have determined that there is an abnormality in fat metabolism in boys with ADHD; these youngsters have low blood levels of DHA and EPA.

DHA and Mood

Sufficient levels of the neurotransmitter serotonin in the brain help bring mood into balance. DHA is necessary to facilitate the flow of serotonin across the synaptic junction. Plus, higher levels of DHA and ARA in the fluid that nourishes and cushions the brain and spinal cord correlate with higher levels of serotonin metabolites. Conversely, deficiency of DHA in the brain, especially in the areas of synapses, seems to relate to low serotonin levels, which, in turn, can lead to depression.

When we find ourselves in a stressful situation, the adrenal glands release cortisol. This hormone is meant to be a short- lived response that enables the body to deal with an acute stressful situation by increasing alertness, pulse, blood pressure, and response time. Unfortunately, depending upon one’s health and lifestyle, stress may not be short lived at all. The long- term effects of chronic physical or emotional stress on the brain are fatigue and depression. Based upon all that we know about the role DHA plays in maintaining optimal mental health, it’s very likely that low levels of DHA are at least partially to blame for the body’s inability to balance itself in instances of sustained physical stress.

A Matter of Heart

The brain is not the only organ that relies on synaptic communication in order to function. It also takes intense communication between cells for the heart to beat in a synchronous rhythm. The heart pumps 200 gallons of blood per day, but it can break down from either physical or emotional factors. DHA is critical for nerve conductivity by virtue of its flexible chemical structure, its ability to conduct nerve impulses, and its smoothness as part of the cell membrane that lines all blood vessels.
Several areas of research have indicated that DHA contributes to heart health in a number of ways, such as by:

• Facilitating intracellular communication to prevent arrhythmia
• Decreasing saturated cholesterol plaque
• Decreasing blood stickiness
• Reducing blood pressure
• Reducing heart rate
• Reducing total cholesterol
• Decreasing triglycerides
• Reducing inflammatory proteins
• Relaxing arterial walls
• Reducing stress in general.

All of these functions of DHA are important in the face of increased genetic and dietary disposition to heart disease. If you have a history of elevated blood pressure, increased cholesterol, heart disease, or diabetes in your family, or if you experience chronic physical or emotional stress, you should strongly consider DHA supplementation.

Important As We Age

There are indications that low levels of DHA contribute to the increased risk of senile dementia, a category of conditions that includes Alzheimer’s disease. Studies show that DHA taken daily can improve symptoms of both cerebrovascular dementia, caused by insufficient blood flow to the brain, and true Alzheimer’s disease. Alzheimer’s patients have less DHA in their blood cells; instead, there are high blood levels of DHA breakdown products, including EPA and inflammatory components. In Alzheimer’s patients, the “good” fat is being destroyed—leaving behind inflammatory breakdown products—and it is not resupplied in the body. Thus, the DHA level decreases.

Sight for Sore Eyes

Age-related macular degeneration (AMD) is the leading cause of blindness in the U.S. among people age 65 or older. It develops after a lifetime of damage to the delicate center of the retina called the macula. People with severe macular degeneration lose the ability to drive, read, and even recognize faces. The cycle of rebuilding rods and cones in the retina can be derailed by a number of factors, including overexposure to UV light, decreased blood supply to the eyes, poor digestion, and inadequate nutritional intake.

We can take precautions to prevent and manage macular degeneration. In addition to DHA consumption, researchers indicate that vitamins A, C, D, and E, lutein, lycopene, cysteine, and the amino acid taurine, along with the minerals zinc, magnesium, and selenium, all support the health of the retina.

A group of conditions targeting the optic nerve, glaucoma affects between 2 and 4 percent of American adults. Glaucoma is often called the thief of sight because most people have no apparent symptoms at first. The most common form is primary open-angle glaucoma, which is characterized by the fluctuation of pressure within the eye, loss of peripheral vision, and changes in the optic nerve. African Americans, Hispanics, and the elderly of all races have higher rates of open- angle glaucoma.
Important nutrients for preventing glaucoma include multivitamins and omega-3 fatty acids— especially DHA. Some of the latest eye drops for glaucoma therapy are derivates of omega-3 fatty acids. They work to treat glaucoma by increasing the outflow of fluid.

DHA and Wellness for Life

Genetic factors control much of our development and our innate intelligence. Our tendency to develop certain diseases may be built into our genes, but these diseases will develop only under certain circumstances. Diet is the cornerstone of the broader foundation of health, and nutrition plays a crucial role in maximizing our genetic potential. The gradual depletion of DHA in our modern diet is becoming obvious through the growing incidence of many diseases.

DHA is not a magic bullet, but it’s a necessary component of every cell in our bodies. It’s crucial in all aspects of our health, and nowhere is it more important than in infant nutrition. If we agree that a larger, optimally functioning brain is something worth having—and I think that most of us would agree—then we’ll need to start adding more DHA- rich foods and supplements to our diets.

About the author:

Dr. Rob Abel co-founded the alternative medicine curriculum at Thomas Jefferson University, where he is a former clinical professor of ophthalmology. He has helped found eye banks, holds patents on artificial corneas, and received the senior honor award from the American Academy of Ophthalmology. Dr. Abel has long been a nationally renown teacher of conventional eye therapy. He assisted with the translations of ancient Ayurvedic eye therapies and his mission is bringing mind-body medicine to 21st century eye care. www.eyeadvisory.com

Great idea for a thread, coco - thanks!

I'm currently taking Sea Buckthorn supplements, a rich source of omega oils. My doctor told me it could help with menopausal symptoms and the dermatitis I get on my hands. I'm not sure about the former as yet but it's definitely helped with the latter. Here's a link to some info:

seabuckthorn.co.uk/health.html

Mandy

Hey coco - nice looking thread you got here.

Thanks Mandy, that great information.

And thanks to you also, Ab.

This next article, while quite lengthy, is a very good primer for Vitamin C.

lpi.oregonstate.edu/infocenter/vitamins/vitaminC/

Linus Pauling Institute
Micronutrient Research for Optimum Health

Vitamin C

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin. Unlike most mammals and other animals, humans do not have the ability to make their own vitamin C. Therefore, we must obtain vitamin C through our diet.

Function

Vitamin C is required for the synthesis of collagen, an important structural component of blood vessels, tendons, ligaments, and bone. Vitamin C also plays an important role in the synthesis of the neurotransmitter, norepinephrine. Neurotransmitters are critical to brain function and are known to affect mood. In addition, vitamin C is required for the synthesis of carnitine, a small molecule that is essential for the transport of fat into cellular organelles called mitochondria, where the fat is converted to energy (1). Research also suggests that vitamin C is involved in the metabolism of cholesterol to bile acids, which may have implications for blood cholesterol levels and the incidence of gallstones (2).

Vitamin C is also a highly effective antioxidant. Even in small amounts vitamin C can protect indispensable molecules in the body, such as proteins, lipids (fats), carbohydrates, and nucleic acids (DNA and RNA), from damage by free radicals and reactive oxygen species that can be generated during normal metabolism as well as through exposure to toxins and pollutants (e.g., cigarette smoke). Vitamin C may also be able to regenerate other antioxidants such as vitamin E (1). One recent study of cigarette smokers found that vitamin C regenerated vitamin E from its oxidized form (3).

Deficiency

Scurvy

Severe vitamin C deficiency has been known for many centuries as the potentially fatal disease, scurvy. By the late 1700s the British navy was aware that scurvy could be cured by eating oranges or lemons, even though vitamin C would not be isolated until the early 1930s. Symptoms of scurvy include bleeding and bruising easily, hair and tooth loss, and joint pain and swelling. Such symptoms appear to be related to the weakening of blood vessels, connective tissue, and bone, which all contain collagen. Early symptoms of scurvy like fatigue may result from diminished levels of carnitine, which is needed to derive energy from fat, or from decreased synthesis of the neurotransmitter norepinephrine (see Function). Scurvy is rare in developed countries because it can be prevented by as little as 10 mg of vitamin C daily (4). However, cases have occurred in children and the elderly on very restricted diets (5, 6).

The Recommended Dietary Allowance (RDA)

In the U.S., the recommended dietary allowance (RDA) for vitamin C was revised in 2000 upward from the previous recommendation of 60 mg daily for men and women. The RDA continues to be based primarily on the prevention of deficiency disease, rather than the prevention of chronic disease and the promotion of optimum health. The recommended intake for smokers is 35 mg/day higher than for nonsmokers, because smokers are under increased oxidative stress from the toxins in cigarette smoke and generally have lower blood levels of vitamin C (7).

Recommended Dietary Allowance (RDA) for Vitamin C
Life Stage Age Males (mg/day) Females (mg/day)
Infants 0-6 months 40 (AI) 40 (AI)
Infants 7-12 months 50 (AI) 50 (AI)
Children 1-3 years 15 15
Children 4-8 years 25 25
Children 9-13 years 45 45
Adolescents 14-18 years 75 65
Adults 19 years and older 90 75
Smokers 19 years and older 125 110
Pregnancy 18 years and younger - 80
Pregnancy 19 years and older - 85
Breast-feeding 18 years/younger - 115
Breast-feeding 19 years/ older - 120

Article Continued Below

lpi.oregonstate.edu/infocenter/vitamins/vitaminC/

Linus Pauling Institute
Micronutrient Research for Optimum Health

Vitamin C

Article Continued....

Disease Prevention

The amount of vitamin C required to prevent chronic disease appears to be more than that required for prevention of scurvy. Much of the information regarding vitamin C and the prevention of chronic disease is based on prospective studies, in which vitamin C intake is assessed in large numbers of people who are followed over time to determine whether they develop specific chronic diseases.

Cardiovascular Diseases

Coronary Heart Disease

Until recently, the results of most prospective studies indicated that low or deficient intakes of vitamin C were associated with an increased risk of cardiovascular diseases, and that modest dietary intakes of about 100 mg/day were sufficient for maximal reduction of cardiovascular disease risk among nonsmoking men and women (1). A recent meta-analysis of 14 cohort studies concluded that dietary vitamin C intake, but not supplemental vitamin C intake, was inversely related to coronary heart disease (CHD) risk (8). Thus, some studies did not find significant reductions in CHD risk among vitamin C supplement users in well-nourished populations (9-11). One notable exception was the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study (12). This study found that the risk of death from cardiovascular diseases was 42% lower in men and 25% lower in women who consumed more than 50 mg/day of dietary vitamin C and regularly took vitamin C supplements, corresponding to a total vitamin C intake of about 300 mg/day (13). Results from the Nurses’ Health Study (NHS), based on the follow-up of more than 85,000 women over 16 years, also suggested that higher vitamin C intakes may be cardioprotective (14). In this study, vitamin C intake of more than 359 mg/day from diet plus supplements or supplement use itself was associated with a 27-28% reduction in CHD risk. However, in those women who did not take vitamin C supplements, dietary vitamin C intake was not significantly associated with CHD risk. Hence, both the NHANES I Epidemiologic Follow-up Study (12, 13) and NHS (14) do not support the conclusions of the above meta-analysis (8). Another pooled analysis of nine prospective cohort studies, including more than 290,000 adults who were free of CHD at baseline and followed for an average of ten years, found that those who took more than 700 mg/day of supplemental vitamin C had a 25% lower risk of CHD than those who did not take vitamin C supplements (15). Additionally, a randomized, double-blind, placebo-controlled trial in more than 14,000 older men participating in the Physicians’ Health Study II found that vitamin C supplementation (500 mg/day) for an average of eight years had no significant effect on major cardiovascular events, total myocardial infarction, or cardiovascular mortality (16). However, this study had several limitations (17); see the Linus Pauling Institute’s response to this study. Data from pharmacokinetic studies of vitamin C at the National Institutes of Health (NIH) indicate that plasma and circulating cells—and thus, presumably, total body pool—in healthy, young subjects became fully saturated with vitamin C at a dose of about 400 mg/day (18). Therefore, the results of the pooled analysis of prospective cohort studies as well as individual, large prospective studies, such as the NHANES I Epidemiologic Follow-up Study (12, 13) and NHS (14), together with pharmacokinetic data of vitamin C in humans (18), suggest that maximal reduction of CHD risk may require vitamin C intakes of 400 mg/day or more (19).

Stroke

With respect to vitamin C and cerebrovascular disease, a prospective study that followed more than 2,000 residents of a rural Japanese community for 20 years found that the risk of stroke in those with the highest serum levels of vitamin C was 29% lower than in those with the lowest serum levels of vitamin C (20). Additionally, the risk of stroke in those who consumed vegetables 6-7 days of the week was 54% lower than in those who consumed vegetables 0-2 days of the week. In this population, serum levels of vitamin C were highly correlated with fruit and vegetable intake. Therefore, as in many studies of vitamin C intake and chronic disease risk, it is difficult to separate the effects of vitamin C on stroke risk from the effects of other components of fruits and vegetables, emphasizing the benefits of a diet rich in fruits and vegetables in reducing stroke risk. Hence, plasma vitamin C levels may be a good biomarker for fruit and vegetable intake and other lifestyle factors that contribute to a reduced risk of stroke. A recent 10-year prospective study in 20,649 adults found that those in the top quartile of plasma vitamin C concentrations had a 42% lower risk of stroke compared to those in the lowest quartile (21). A randomized, double-blind, placebo-controlled trial in more than 14,000 older men participating in the Physicians’ Health Study II found that vitamin C supplementation (500 mg/day) for an average of eight years had no significant effect on stroke death, ischemic stroke, or hemorrhagic stroke (16). However, this study had numerous limitations that make it difficult to draw conclusions for the general population (17); see the Linus Pauling Institute’s response to this study.

Cancer

A large number of studies have shown that increased consumption of fresh fruits and vegetables is associated with a reduced risk for most types of cancer (22). Such studies were the basis for dietary guidelines endorsed by the U.S. Department of Agriculture and the National Cancer Institute, which recommended at least five servings of fruits and vegetables per day. U.S. government organizations currently recommend eating a variety of fruits and vegetables daily; the recommended serving number depends on total caloric intake, which is governed by age, gender, body composition, and physical activity level (23). A number of case-control studies have investigated the role of vitamin C in cancer prevention. Most have shown that higher intakes of vitamin C are associated with decreased incidence of cancers of the mouth, throat and vocal chords, esophagus, stomach, colon-rectum, and lung. Because the possibility of bias is greater in case-control studies, prospective cohort studies are generally given more weight when evaluating the effect of nutrient intake on disease. In general, prospective studies in which the lowest intake group consumed more than 86 mg of vitamin C daily have not found differences in cancer risk, while studies finding significant cancer risk reductions found them in people consuming at least 80 to 110 mg of vitamin C daily (1).

A prospective study that followed 870 men over a period of 25 years found that those who consumed more than 83 mg of vitamin C daily had a striking, 64% reduction in lung cancer compared with those who consumed less than 63 mg per day (24). However, a pooled analysis of eight prospective studies concluded that dietary vitamin C was not related to lung cancer when the analysis was controlled for other dietary factors (25). Although most large prospective studies observed no association between breast cancer and vitamin C intake, two studies found dietary vitamin C intake to be inversely associated with breast cancer risk in certain subgroups. In the Nurses' Health Study, premenopausal women with a family history of breast cancer who consumed an average of 205 mg/day of vitamin C from foods had a 63% lower risk of breast cancer than those who consumed an average of 70 mg/day (26). In the Swedish Mammography Cohort, overweight women who consumed an average of 110 mg/day of vitamin C had a 39% lower risk of breast cancer compared to overweight women who consumed an average of 31 mg/day (27). A number of observational studies have found increased dietary vitamin C intake to be associated with decreased risk of stomach cancer, and laboratory experiments indicate that vitamin C inhibits the formation of carcinogenic compounds in the stomach (28, 29). Infection with the bacteria, Helicobacter pylori (H. pylori), is known to increase the risk of stomach cancer and also appears to lower the vitamin C content of stomach secretions. Although two intervention studies did not find a decrease in the occurrence of stomach cancer with vitamin C supplementation (7), more recent research suggests that vitamin C supplementation may be a useful addition to standard H. pylori eradication therapy in reducing the risk of gastric cancer (30, 31). Another intervention trial, a randomized, double-blind, placebo-controlled trial in more than 14,000 older men participating in the Physicians’ Health Study (PHS) II, reported vitamin C supplementation (500 mg/day) for an average of eight years had no significant effect on total cancer or site-specific cancers, including colorectal, lung, and prostate cancer (32). However, the PHS II had several limitations; see the Linus Pauling Institute’s response to the PHS II.

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Cataracts

Cataracts are a leading cause of visual impairment throughout the world. In the U.S., cataract-related expenditures are estimated to exceed $3 billion annually (33). Cataracts occur more frequently and become more severe as people age. Decreased vitamin C levels in the lens of the eye have been associated with increased severity of cataracts in humans. Some, but not all, studies have observed increased dietary vitamin C intake (34, 35) and increased blood levels of vitamin C (36, 37) to be associated with decreased risk of cataracts. In general, those studies that have found a relationship suggest that vitamin C intake may have to be higher than 300 mg/day for a number of years before a protective effect can be detected (1). A 7-year controlled intervention trial in 4,629 men and women found that a daily antioxidant supplement containing 500 mg of vitamin C, 400 IU of vitamin E, and 15 mg of beta-carotene had no effect on the development and progression of age-related cataracts compared to a placebo (38). Therefore, the relationship between vitamin C intake and the development of cataracts requires further clarification before specific recommendations can be made.

Gout

Gout, a condition that afflicts more than 1% of U.S. adults, is characterized by abnormally high blood levels of uric acid (urate) (39). Urate crystals may form in joints, resulting in inflammation and pain, as well as in the kidneys and urinary tract, resulting in kidney stones. The tendency to develop elevated blood uric acid levels and gout is often inherited; however, dietary and lifestyle modification may be helpful in both the prevention and treatment of gout (40). In an observational study that included 1,387 men, higher intakes of vitamin C were associated with lower serum levels of uric acid (41). More recently, a prospective study that followed a cohort of 46,994 men for 20 years found that total daily vitamin C intake was inversely associated with risk of gout, with higher intakes being associated with greater risk reductions (42). The results of this study also indicate that supplemental vitamin C may be helpful in the prevention of gout (42). Interestingly, a randomized, double-blind, placebo-controlled trial in 184 adult nonsmokers reported that vitamin C supplementation (500 mg/day) for two months lowered serum concentrations of uric acid compared to placebo (43).

Lead toxicity

Although the use of lead paint and leaded gasoline has been discontinued in the U.S., lead toxicity continues to be a significant health problem, especially in children living in urban areas. Abnormal growth and development have been observed in infants of women exposed to lead during pregnancy, while children who are chronically exposed to lead are more likely to develop learning disabilities, behavioral problems, and to have a low IQ. In adults, lead toxicity may result in kidney damage, high blood pressure, and anemia. In a study of 747 older men, blood lead levels were significantly higher in those who reported total dietary vitamin C intakes averaging less than 109 mg/day compared to those who reported higher vitamin C intakes (44). A much larger study of 19,578 people, including 4,214 children from six to 16 years of age, found higher serum vitamin C levels to be associated with significantly lower blood lead levels (45). A U.S. national survey of more than 10,000 adults found that blood lead levels were inversely related to serum vitamin C levels (46). An intervention trial that examined the effects of vitamin C supplementation on blood lead levels in 75 adult male smokers found that 1,000 mg/day of vitamin C resulted in significantly lower blood lead levels over a four-week treatment period compared to placebo (47). A lower dose of 200 mg/day did not significantly affect blood lead levels, despite the finding that serum vitamin C levels were not different than those in the group who took 1,000 mg/day. The mechanism for the relationship between vitamin C intake and blood lead levels is not known, although it has been postulated that vitamin C may inhibit intestinal absorption or enhance urinary excretion of lead.

Role in Immunity

Vitamin C affects several components of the human immune system; for example, vitamin C has been shown to stimulate both the production (48-52) and function (53, 54) of leukocytes (white blood cells), especially neutrophils, lymphocytes, and phagocytes. Specific measures of functions stimulated by vitamin C include cellular motility (54), chemotaxis (53, 54), and phagocytosis (53). Neutrophils, which attack foreign bacteria and viruses, seem to be the primary cell type stimulated by vitamin C, but lymphocytes and other phagocytes are also affected (55). Additionally, several studies have shown that supplemental vitamin C increases serum levels of antibodies (56, 57) and C1q complement proteins (58-60) in guinea pigs, which—like humans—cannot synthesize vitamin C and hence depend on dietary vitamin C. However, some studies have reported no beneficial changes in leukocyte production or function with vitamin C treatment (61-64). Vitamin C may also protect the integrity of immune cells. Neutrophils, mononuclear phagocytes, and lymphocytes accumulate vitamin C to high concentrations, which can protect these cell types from oxidative damage (52, 65, 66). In response to invading microorganisms, phagocytic leukocytes release non-specific toxins, such as superoxide radicals, hypochlorous acid (“bleach”), and peroxynitrite; these reactive oxygen species kill pathogens and, in the process, can damage the leukocytes themselves (67). Vitamin C, through its antioxidant functions, has been shown to protect leukocytes from such effects of autooxidation (68). Phagocytic leukocytes also produce and release cytokines, including interferons, which have antiviral activity (69). Vitamin C has been shown to increase interferon levels in vitro (70).

It is widely thought by the general public that vitamin C boosts the function of the immune system, and accordingly, may protect against viral infections and perhaps other diseases. While some studies suggest the biological plausibility of vitamin C as an immune enhancer, human studies published to date are conflicting. Further, controlled clinical trials of appropriate statistical power would be necessary to determine if supplemental vitamin C boosts the immune system.

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Disease Treatment

Cardiovascular Diseases

Vasodilation

The ability of blood vessels to relax or dilate (vasodilation) is compromised in individuals with atherosclerosis. Damage to the heart muscle caused by a heart attack and damage to the brain caused by a stroke are related, in part, to the inability of blood vessels to dilate enough to allow blood flow to the affected areas. The pain of angina pectoris is also related to insufficient dilation of the coronary arteries. Impaired vasodilation has been identified as an independent risk factor for cardiovascular disease (71). Many randomized, double-blind, placebo-controlled studies have shown that treatment with vitamin C consistently results in improved vasodilation in individuals with coronary heart disease as well as those with angina pectoris, congestive heart failure, diabetes, high cholesterol, and high blood pressure (1, 72-74). Improved vasodilation has been demonstrated at an oral dose of 500 mg of vitamin C daily (72).

Hypertension

Individuals with high blood pressure (hypertension) are at increased risk of developing cardiovascular diseases. Several, but not all, studies have demonstrated a blood pressure lowering effect of vitamin C supplementation (75). A small study in individuals with hypertension found that vitamin C supplementation with 500 mg/day for six weeks slightly decreased systolic blood pressure (1.8 mm Hg reduction) compared to a placebo (76). Another study in individuals with elevated blood pressure found that a daily supplement of 500 mg of vitamin C resulted in an average drop in systolic blood pressure of 9% after four weeks (77). It should be noted that those participants who were taking antihypertensive medications continued taking them throughout the four-week study. Because the findings regarding vitamin C and high blood pressure have not yet been replicated in larger studies, it is important for individuals with significantly elevated blood pressure to continue current therapy (medication, lifestyle changes, etc.) in consultation with their health care provider.

Cancer

Studies in the 1970s and 1980s conducted by Linus Pauling, Ewan Cameron, and colleagues suggested that very large doses of vitamin C (10 grams/day intravenously for ten days followed by at least 10 grams/day orally indefinitely) were helpful in increasing the survival time and improving the quality of life of terminal cancer patients (78). However, two randomized placebo-controlled studies conducted at the Mayo Clinic found no differences in outcome between terminal cancer patients receiving 10 grams/day of vitamin C orally or placebo (79, 80). There were significant methodological differences between the Mayo Clinic and Pauling's studies, and recently, researchers from the NIH suggested that the route of administration (intravenous versus oral) may have been the key to the discrepant results. Intravenous (IV) administration can result in much higher blood levels of vitamin C than oral administration, and vitamin C levels that are toxic to cancer cells in culture can be achieved in humans only with intravenous but not oral administration of vitamin C (81). Dr. Mark Levine and colleagues at NIH have investigated the anticancer mechanism responsible for vitamin C and reported that it involves production of hydrogen peroxide, which is selectively toxic to cancer cells (82-84). Thus, it appears reasonable to reevaluate the use of high-dose vitamin C as adjunctive cancer therapy.

Currently, there are no results from controlled clinical trials indicating that vitamin C would adversely affect the survival of cancer patients. Recently, two phase I clinical trials in patients with advanced cancer found that intravenous administration of vitamin C at doses up to 1.5 g/kg of body weight was well tolerated and safe in pre-screened patients (85, 86); other phase I trials are ongoing (87). Additionally, phase II clinical trials evaluating the efficacy of vitamin C in cancer treatment are currently under way (87). Some case reports have suggested that intravenous vitamin C may aid in cancer treatment (88, 89). However, vitamin C should not be used in place of therapy that has been demonstrated effective in the treatment of a particular type of cancer, for example, chemotherapy or radiation therapy. If an individual with cancer chooses to take vitamin supplements, it is important that the clinician coordinating his or her treatment is aware of the type and dose of each supplement. While research is under way to determine whether combinations of antioxidant vitamins might be beneficial as an adjunct to conventional cancer therapy, definitive conclusions are not yet possible (90). For more information about intravenous vitamin C and cancer, see the Linus Pauling Institute Spring/Summer 2006 Research Newsletter.

In a presentation at a meeting of the American Cancer Society, a scientist suggested that supplemental vitamin C might enhance the growth of cancer cells or protect them from cell-killing free radicals produced by radiation and some forms of chemotherapy. An article published in the Spring/Summer 2000 issue of the Linus Pauling Institute Newsletter, Is vitamin C harmful for cancer patients?, provides additional insight on this topic.

For information about the clinical use of high-dose intravenous vitamin C as an adjunct in cancer treatment, visit the University of Kansas Medical Center Program in Integrative Medicine Web site.

Diabetes Mellitus

Cardiovascular diseases (heart disease and stroke) are the leading cause of death in individuals with diabetes. Evidence that diabetes is a condition of increased oxidative stress led to the hypothesis that higher intakes of antioxidant nutrients could help decrease cardiovascular disease risk in diabetic individuals. In support of this hypothesis, a 16-year study of 85,000 women, 2% of whom were diabetic, found that vitamin C supplement use (400 mg/day or more) was associated with significant reductions in the risk of fatal and nonfatal coronary heart disease in the entire cohort as well as in those with diabetes (14). In contrast, a 15-year study of postmenopausal women found that diabetic women who reported taking at least 300 mg/day of vitamin C from supplements when the study began were at significantly higher risk of death from coronary heart disease and stroke than those who did not take vitamin C supplements (91). Vitamin C supplement use was not associated with a significant increase in cardiovascular disease mortality in the cohort as a whole. Although a number of observational studies have found that higher dietary intakes of vitamin C are associated with lower cardiovascular disease risk, randomized controlled trials have not found antioxidant supplementation that included vitamin C to reduce the risk of cardiovascular disease in diabetic or other high-risk individuals (92, 93).

It is possible that genetic differences may influence the effect of vitamin C supplementation on cardiovascular disease. When the results of one randomized controlled trial were reanalyzed based on haptoglobin genotype, antioxidant therapy (1,000 mg/day of vitamin C + 800 IU/day of vitamin E) was associated with improvement of coronary atherosclerosis in diabetic women with two copies of the haptoglobin 1 gene but worsening of coronary atherosclerosis in those with two copies of the haptoglobin 2 gene (94). The significance of these findings is not entirely clear, but they suggest that there may be a subpopulation of people with diabetes who will benefit from antioxidant therapy, while others may not benefit or could actually be harmed.

Common cold

The work of Linus Pauling stimulated public interest in the use of large doses (greater than 1 gram/day, also sometimes called "mega-doses") of vitamin C to prevent the common cold (95). In the past 30 years, numerous placebo-controlled trials have examined the effect of vitamin C supplementation on the prevention and treatment of colds. A meta-analysis of 30 placebo-controlled prevention trials found that vitamin C supplementation in doses up to 2 grams/day did not decrease the incidence of colds (96). However, in a subgroup of marathon runners, skiers, and soldiers training in the Arctic, doses ranging from 250 mg/day to 1 gram/day decreased the incidence of colds by 50%. Overall, the preventive use of vitamin C supplementation reduced the duration of colds by about 8% in adults and 14% in children. Most of the prevention trials used a dose of 1 gram/day. When treatment was started at the onset of symptoms, vitamin C supplementation did not shorten the duration of colds in seven placebo-controlled trials at doses ranging from 1-4 grams/day. Additionally, the same authors completed a meta-analysis of the 15 trials that assessed the effect of vitamin C on cold severity; no consistent evidence that vitamin C was beneficial in ameliorating cold symptoms was found in this analysis. Thus, the overall conclusion of this meta-analysis was that vitamin C is ineffective as a prophylactic against the common cold, but individuals under stress, such as those exposed to strenuous physical exercise or cold weather, may experience some therapeutic benefit (96). More recently, a randomized, double-blind (but not placebo-controlled) study reported that those who took 500 mg/day of supplemental vitamin C had a 66% lower risk for contracting three or more colds in a five-year period compared to those who took 50 mg/day of supplemental vitamin C (97). The authors of this study did not find any significant differences in the two groups when analyzing data regarding cold severity or duration. However, the doses used in this study were smaller than those used in most of the previous studies.

Some authors have asserted that the studies included in the above mentioned meta-analysis (96) utilized daily doses of vitamin C that would be too low to observe a therapeutic benefit (98, 99). Additionally, results of a recent pharmacokinetic study suggest that dividing the daily dose and administering it several times throughout the day, thereby increasing dose frequency, would better sustain plasma ascorbate levels (81). Large-scale, controlled clinical trials using pharmacological doses of vitamin C are necessary to determine whether or not higher doses of vitamin C have any therapeutic value in preventing or treating the common cold. For a more detailed discussion on vitamin C and the common cold, see the Linus Pauling Institute's Spring/Summer 2006 Research Newsletter.

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Vitamin C

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Sources

Food Sources

As shown in the table below, different fruits and vegetables vary in their vitamin C content (100), but five servings (2½ cups) of fruits and vegetables should average out to about 200 mg of vitamin C. If you wish to check foods for their nutrient content, search the USDA food composition database.

Food Serving Vitamin C (mg)
Orange juice ¾ cup (6 ounces) 62-93
Grapefruit juice ¾ cup (6 ounces) 62-70
Orange 1 medium 70
Grapefruit ½ medium 38
Strawberries 1 cup, whole 85
Tomato 1 medium 16
Sweet red pepper ½ cup, raw chopped 95
Broccoli ½ cup, cooked 51
Potato 1 medium, baked 17

Supplements

Vitamin C (L-ascorbic acid) is available in many forms, but there is little scientific evidence that any one form is better absorbed or more effective than another. Most experimental and clinical research uses ascorbic acid or sodium ascorbate.

Natural vs. synthetic vitamin C

Natural and synthetic L-ascorbic acid are chemically identical and there are no known differences in their biological activities or bioavailabilities (101).

Mineral ascorbates

Mineral salts of ascorbic acid are buffered and, therefore, less acidic than ascorbic acid. Some people find them less irritating to the gastrointestinal tract than ascorbic acid. Sodium ascorbate and calcium ascorbate are the most common forms, although a number of other mineral ascorbates are available. Sodium ascorbate provides 111 mg of sodium (889 mg of ascorbic acid) per 1,000 mg of sodium ascorbate, and calcium ascorbate generally provides 90-110 mg of calcium (890-910 mg of ascorbic acid) per 1,000 mg of calcium ascorbate.

Vitamin C with bioflavonoids

Bioflavonoids are a class of water-soluble plant pigments that are often found in vitamin C-rich fruits and vegetables, especially citrus fruits. There is little evidence that the bioflavonoids in most commercial preparations increase the bioavailability or efficacy of vitamin C (102). Studies in cell culture indicate that a number of flavonoids inhibit the transport of vitamin C into cells (103-105), and supplementation of rats with quercetin and vitamin C decreased the intestinal absorption of vitamin C (103). More research is needed to determine the significance of these findings in humans.

Ascorbate and vitamin C metabolites

One supplement, Ester-C® contains mainly calcium ascorbate, but also contains small amounts of the vitamin C metabolites dehydroascorbate (oxidized ascorbic acid), calcium threonate, and trace levels of xylonate and lyxonate. Although the metabolites are supposed to increase the bioavailability of vitamin C, the only published study in humans addressing this issue found no difference between Ester-C® and commercially available ascorbic acid tablets with respect to the absorption and urinary excretion of vitamin C (102). Ester-C® should not be confused with ascorbyl palmitate, which is also marketed as "vitamin C ester" (see below).

Ascorbyl palmitate

Ascorbyl palmitate is actually a vitamin C ester (i.e., vitamin C that has been esterified to a fatty acid). In this case, vitamin C is esterified to the saturated fatty acid, palmitic acid, resulting in a fat-soluble form of vitamin C. Ascorbyl palmitate has been added to a number of skin creams due to interest in its antioxidant properties as well as its importance in collagen synthesis (106). Although ascorbyl palmitate is also available as an oral supplement, it is likely that most of it is hydrolyzed (broken apart) to ascorbic acid and palmitic acid in the digestive tract before it is absorbed (107). Ascorbyl palmitate is also marketed as "vitamin C ester," which should not be confused with Ester-C® (see above).

For a more detailed review of scientific research on the bioavailability of different forms of vitamin C, see The Bioavailability of Different Forms of Vitamin C.

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Safety

Toxicity

A number of possible problems with very large doses of vitamin C have been suggested, mainly based on in vitro experiments or isolated case reports, including genetic mutations, birth defects, cancer, atherosclerosis, kidney stones, "rebound scurvy," increased oxidative stress, excess iron absorption, vitamin B12 deficiency, and erosion of dental enamel. However, none of these alleged adverse health effects have been confirmed, and there is no reliable scientific evidence that large amounts of vitamin C (up to 10 grams/day in adults) are toxic or detrimental to health. The concerns of kidney stone formation with vitamin C supplementation are discussed below. With the latest RDA published in 2000, a tolerable upper intake level (UL) for vitamin C was set for the first time. A UL of 2 grams (2,000 milligrams) daily was recommended in order to prevent most adults from experiencing diarrhea and gastrointestinal disturbances (7). Such symptoms are not generally serious, especially if they resolve with temporary discontinuation or reduction of high-dose vitamin C supplementation. For a more thorough discussion of the Linus Pauling Institute's response to the UL for vitamin C, see the article, The New Recommendations for Dietary Antioxidants: A Response and Position Statement by the Linus Pauling Institute, in the Spring/Summer 2000 Newsletter. A more detailed discussion of vitamin C and the risk of kidney stones can be found below and in the article, What About Vitamin C and Kidney Stones?, in the Fall/Winter 1999 Newsletter.

Tolerable Upper Intake Level (UL) for Vitamin C
Age Group UL (mg/day)
Infants 0-12 months Not possible to establish*
Children 1-3 years 400
Children 4-8 years 650
Children 9-13 years 1,200
Adolescents 14-18 years 1,800
Adults 19 years/ older 2,000

*Source of intake should be from foods or formula only.

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Does vitamin C promote oxidative damage under physiological conditions? Vitamin C is known to function as a highly effective antioxidant in living organisms. However, in test tube experiments, vitamin C can interact with some free metal ions to produce potentially damaging free radicals. Although free metal ions are not generally found under physiological conditions, the idea that high doses of vitamin C might be able to promote oxidative damage in vivo has received a great deal of attention. Widespread publicity has been given to a few studies suggesting a pro-oxidant effect of vitamin C (108, 109), but these studies turned out to be either flawed or of no physiological relevance. A comprehensive review of the literature found no credible scientific evidence that supplemental vitamin C promotes oxidative damage under physiological conditions or in humans (110). Studies that report a pro-oxidant effect for vitamin C should be evaluated carefully to determine whether the study system was physiologically relevant and to rule out the possibility of methodological and design flaws.

For example, a study in the June 15, 2001 issue of the journal Science reported that lipid hydroperoxides (rancid fat molecules) can react with vitamin C to form products that could potentially harm DNA, although the reaction of these products with DNA was not demonstrated in this study (108). To find out why the Linus Pauling Institute considers the study's conclusions unwarranted, see Vitamin C doesn't cause cancer! in the Linus Pauling Institute Newsletter.

Kidney Stones

Because oxalate is a metabolite of vitamin C, there is some concern that high vitamin C intake could increase the risk of oxalate kidney stones. Some (111-113), but not all (114-116), studies have reported that supplemental vitamin C increases urinary oxalate levels. Whether any increase in oxalate levels would translate to an elevation in risk for kidney stones has been examined in epidemiological studies. Two large prospective studies, one following 45,251 men for six years and the other following 85,557 women for 14 years, reported that consumption of ≥1,500 mg of vitamin C daily did not increase the risk of kidney stone formation compared to those consuming <250 mg daily. However, a more recent prospective study that followed 45,619 men for 14 years found that those who consumed ≥1,000 mg/day of vitamin C had a 41% higher risk of kidney stones compared to men consuming <90 mg of vitamin C daily—the current recommended dietary allowance (see RDA; (117)). In this study, low intakes (90-249 mg/day) of vitamin C (primarily from the diet) were also associated with a significantly elevated risk. Supplemental vitamin C intake was only weakly associated with increased risk of kidney stones in this study (117). Despite conflicting results, it may be prudent for individuals predisposed to oxalate kidney stone formation to avoid high-dose vitamin C supplementation.

Drug Interactions

A number of drugs are known to lower vitamin C levels, requiring an increase in its intake. Estrogen-containing contraceptives (birth control pills) are known to lower vitamin C levels in plasma and white blood cells. Aspirin can lower vitamin C levels if taken frequently. For example, taking two aspirin tablets every six hours for a week has been reported to lower vitamin C levels in white blood cells by 50%, primarily by increasing urinary excretion of vitamin C (118).

There is some evidence, though controversial, that vitamin C interacts with anticoagulant medications (blood thinners) like warfarin (Coumadin). Large doses of vitamin C may block the action of warfarin, requiring an increase in dose to maintain its effectiveness. Individuals on anticoagulants should limit their vitamin C intake to 1 gram/day and have their prothrombin time monitored by the clinician following their anticoagulant therapy. Because high doses of vitamin C have also been found to interfere with the interpretation of certain laboratory tests (e.g., serum bilirubin, serum creatinine, and the guaiac assay for occult blood), it is important to inform one's health care provider of any recent supplement use (119).

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Antioxidant Supplements and HMG-CoA Reductase Inhibitors (Statins)

A 3-year randomized controlled trial in 160 patients with documented coronary heart disease (CHD) and low HDL levels found that a combination of simvastatin (Zocor) and niacin increased HDL2 levels, inhibited the progression of coronary artery stenosis (narrowing), and decreased the frequency of cardiovascular events, such as myocardial infarction (heart attack) and stroke (120). Surprisingly, when an antioxidant combination (1,000 mg vitamin C, 800 IU alpha-tocopherol, 100 mcg selenium, and 25 mg beta-carotene daily) was taken with the simvastatin-niacin combination, the protective effects were diminished. Since the antioxidants were taken together in this trial, the individual contribution of vitamin C cannot be determined. In contrast, a much larger randomized controlled trial in more than 20,000 men and women with CHD or diabetes found that simvastatin and an antioxidant combination (600 mg vitamin E, 250 mg vitamin C, and 20 mg beta-carotene daily) did not diminish the cardioprotective effects of simvastatin therapy over a 5-year period (121). These contradictory findings indicate that further research is needed on potential interactions between antioxidant supplements and cholesterol-lowering drugs, such as HMG-CoA reductase inhibitors (statins).

Linus Pauling Institute Recommendation

For healthy men and women, the Linus Pauling Institute recommends a vitamin C intake of at least 400 mg daily. Consuming at least five servings (2½ cups) of fruits and vegetables daily provides about 200 mg of vitamin C. Most multivitamin supplements provide 60 mg of vitamin C. To make sure you meet the Institute’s recommendation, supplemental vitamin C in two separate 250-mg doses taken in the morning and evening is recommended.

Older adults (65 years and older)

Although it is not yet known with certainty whether older adults have higher requirements for vitamin C than younger people, some older populations have been found to have vitamin C intakes considerably below the RDA of 75 and 90 mg/day for women and men, respectively. A vitamin C intake of at least 400 mg daily may be particularly important for older adults who are at higher risk for chronic diseases. In addition, a meta-analysis of 36 publications examining the relationship between vitamin C intake and plasma concentrations of vitamin C concluded that older adults (age 60-96 years) have considerably lower plasma levels of vitamin C following a certain intake of vitamin C compared with younger individuals (age 15-65 years) (122), suggesting that older adults may have higher vitamin C requirements. Studies conducted at the National Institutes of Health indicated that plasma and circulating cells in healthy, young subjects attain near-maximal concentrations of vitamin C at a dose of about 400 mg/day—a dose much higher than the current RDA. Pharmacokinetic studies in older adults have not yet been conducted, but evidence suggests that the efficiency of one of the molecular mechanisms for the cellular uptake of vitamin C declines with age (123). Because maximizing blood levels of vitamin C may be important in protection against oxidative damage to cells and biological molecules, a vitamin C intake of at least 400 mg daily is particularly important for older adults who are at higher risk for chronic diseases caused, in part, by oxidative damage, such as heart disease, stroke, certain cancers, and cataract.

For more information on the difference between Dr Linus Pauling's recommendation and the Linus Pauling Institute's recommendation for vitamin C intake, select the highlighted text.

References

Written in January 2006 by:
Jane Higdon, Ph.D.
Linus Pauling Institute
Oregon State University

Updated in November 2009 by:
Victoria J. Drake, Ph.D.
Linus Pauling Institute
Oregon State University

Reviewed in November 2009 by:
Balz Frei, Ph.D.
Director and Endowed Chair, Linus Pauling Institute
Distinguished Professor, Dept. of Biochemistry and Biophysics
Oregon State University

Copyright 2000-2012 Linus Pauling Institute

Disclaimer

The Linus Pauling Institute Micronutrient Information Center provides scientific information on the health aspects of dietary factors and supplements, foods, and beverages for the general public. The information is made available with the understanding that the author and publisher are not providing medical, psychological, or nutritional counseling services on this site. The information should not be used in place of a consultation with a competent health care or nutrition professional.

The information on dietary factors and supplements, foods, and beverages contained on this Web site does not cover all possible uses, actions, precautions, side effects, and interactions. It is not intended as nutritional or medical advice for individual problems. Liability for individual actions or omissions based upon the contents of this site is expressly disclaimed.

A nice little basic multi vitamin primer:

www.sparkpeople.com/resource/reference_vitamins.asp

Why Too Much Can Be Bad

Vitamins are important and good for your health. Many have the notion that if a little is good, then more must be better. This is a myth which can be very dangerous. Vitamins actually function primarily as catalysts, regulating chemical reactions within the body. They are also essential for the release of energy from food. But they do not provide calories or energy themselves. Each vitamin serves one or more special functions in the body that no other nutrient can. Deficiencies also have specific consequences.

To become active in the body, each vitamin must associate with a special protein. Together they form an active enzyme ready to regulate body processes. However, it is important to realize that once the special proteins in the body cells are filled up with a particular vitamin, no further activity can possibly be achieved by adding any more of that vitamin. The excess vitamin serves as a chemical substance that in many cases can do damage to the body. This is why over-dosages of vitamin supplements cannot benefit the body and may in fact be harmful.

Vitamins are sometimes referred to as micronutrients since they are needed in only small amounts. Vitamins are measured in milligrams (one-thousandth of a gram) and in micrograms (one-millionth of a gram), or in International Units. An inadequacy of a minute amount of a vitamin can have far-reaching effects on body processes and health. Too much of certain vitamins, though seemingly a small amount, can produce harmful toxic conditions.

The Vitamin Family

Vitamins belong in two groups: water-soluble and fat-soluble. Each name describes an important quality—how it is carried in food and transported in your body.

Water-soluble vitamins dissolve in water. They include the B-complex vitamins and vitamin C. They are carried in your bloodstream and are not stored in the body in significant amounts. Your body uses the amount that is needed, and then the extra is excreted in the urine. Since your body does not store water-soluble vitamins, regular intake is necessary. Water-soluble vitamins are also destroyed more easily during food storage, processing and preparation.

Fat-soluble vitamins dissolve in fat. To be carried in your bloodstream and throughout your body, they must be attached to body chemicals made of lipids or fat. Four vitamins are fat-soluble: A, D, E, and K. Your body is able to store these fat-soluble vitamins in body fat. Getting a new supply each day is not essential. Harmful, toxic levels of the fat-soluble vitamins can occur when excess amounts are consumed on a regular basis, usually from supplements.

Fat-Soluble Vitamins

Vitamin A

Functions
Vitamin A is needed for night vision and helps the eyes adjust to lower levels of light. It promotes the growth of skin, bones, and male and female reproductive organs. Vitamin A protects you from infections by keeping the skin and tissues in your mouth, stomach, intestines, respiratory, genital, and urinary tracts healthy. Beta-carotene is converted into vitamin A in the body. Beta-carotene may reduce the risk of certain types of cancer and possibly heart disease.

Deficiencies
Lack of vitamin A may lead to night blindness, dry eyes, eye infections, dry scaly skin, reproductive problems, and slow growth.

Excesses
Because vitamin A is stored in the body, large quantities can be very harmful. Symptoms of overdosing include headaches, dry scaly skin, liver damage, bone and joint pain, vomiting, appetite loss, nerve damage, and birth defects. The Tolerable Upper Intake Level for vitamin A is 3,000 micrograms for adult males and females.

Amount Needed
The recommended intake for adult males is 900 micrograms and 700 micrograms for adult females.

Food Sources
Your body can get vitamin A in two forms: retinols and beta-carotene. Retinols are found in foods that come from animals such as meat, milk fortified with A, fish oil and eggs. Bete-carotene is found in red, yellow, and orange vegetables and fruits, and many dark-green leafy vegetables.

Vitamin D

Functions
Vitamin D is one member of a large team of nutrients and hormones that promotes the absorption of calcium and phosphorus. Vitamin D helps deposit these minerals in your bones and teeth, thus making them stronger and healthier.

Deficiencies
Lack of vitamin D in childhood may lead to a condition called rickets, in which bones and teeth are weak. In older adults a lack of vitamin D can cause a condition called osteomalacia, a softening of the bones. It can also cause bone loss called osteoporosis.

Excesses
Because vitamin D is stored in the body, large quantities can be toxic. Kidney stones, kidney damage, weak bones, excessive bleeding, muscle weakness and damage can occur. The Tolerable Upper Intake Level for vitamin D is 4,000 IU for adults.

Amount Needed
The recommended daily intake for adults up to age 70 is 600 IU. After age 70, the recommended intake goes up to 800 IU daily.

Food Sources
Vitamin D is found naturally in fish and fish-liver oils. However it is also found in vitamin D fortified milk. Vitamin D is known as the “sunshine vitamin” because it is made in your skin when the ultraviolet light hits your skin. If you eat a balanced diet and get outside in the sunshine at least 1 ½ to 2 hours a week, you should be getting all the vitamin D you need. As a precaution, especially during the winter, for people who do not get outdoors much (especially during the winter), and for older people whose skin is less efficient with this conversion, milk is fortified with vitamin D. If you do not drink milk, ask your health care professional about supplementation. Note: most cheese and yogurt products are NOT made with fortified milk.

Vitamin E

Functions
Vitamin E is the bodyguard for your body. It works as an antioxidant, preventing a chemical reaction called oxidation, which can sometimes result in harmful effects in your body. For example, vitamin E protects polyunsaturated fats, red blood cells, and vitamin A from the destructive forces of oxygen. The cells of the lungs are continually exposed to the destructive properties of oxygen, but vitamin E protects these tissues. It is important for proper functioning of nerves, blood and muscle tissue.

Deficiencies
Because it is abundant in many foods, a deficiency of vitamin E is rare. However, there are two exceptions. Since the transfer of vitamin E from mother to infant occurs during the very last weeks of pregnancy, premature infants may be deficient. Without vitamin E, the red blood cells rupture and the infant becomes anemic. There are also some people who are unable to absorb fat normally and therefore develop a vitamin E deficiency. In this case the nervous system can be affected.

Excesses
People who take large doses by mouth do not seem to have major symptoms. However blurred vision, diarrhea, dizziness, headache, nausea, stomach cramps, unusual tiredness, and weakness have been reported. The Tolerable Upper Intake Limit for vitamin E is 1,000 milligrams daily.
Amount Needed Vitamin E is a group of substances call tocopherals with different potencies. The amount is given in alpha-tocopherol equivalents as a standard measure. The recommended daily intake for adults is 15 alpha-tocopherol equivalents.

Food Sources
E is found in a variety of foods. The best sources include wheat germ and wheat germ oil, soybean, corn, safflower and cottonseed oil. Good sources include margarine, mayonnaise, salad dressings, nuts, seeds, peanuts, and peanut butter. Fair sources include whole grains, corn, beef liver, leafy-green vegetables, fish and eggs.

Vitamin K

Functions
Vitamin K refers to a group of chemically similar fat-soluble compounds. Vitamin K is necessary to make proteins that cause your blood to coagulate and clot. This stops bleeding. Vitamin K also helps your body make other body proteins for your blood, bones, and kidneys.

Deficiencies
Vitamin K deficiency is rare. However, a deficiency can lead to defective blood coagulation and increased bleeding and bruising. Certain health problems can cause deficiencies such as malnutrition due to alcohol dependency, celiac disease, ulcerative colitis, cystic fibrosis, and short bowel syndrome. Some drugs may reduce vitamin K levels by altering liver function or destroying the intestinal bacteria that makes vitamin K.

Excesses
No symptoms have been observed with excess intake. Moderation is still the best approach. People taking blood-thinning drugs and anticoagulants such as warfarin (coumadin) need to eat foods with vitamin K in moderation. Too much can make blood clot faster. The Tolerable Upper Intake Level for vitamin K has not been determined.

Amount Needed
The recommended daily intake for adult males is 120 micrograms and 90 micrograms for adult females.

Food Sources
Vitamin K can be made in your digestive tract by the billions of bacteria that are in your intestines. Some of these bacteria synthesize vitamin K that your body can then absorb. Good food sources include green-leafy vegetables such as spinach and broccoli, pork, liver, whole wheat, oats, and bran. Fair sources include fruits, vegetables, seeds, tubers, milk, and eggs.

Water-Soluble Vitamins

Thiamin(vitamin B-1)

Functions
In all the cells of the body, thiamin is needed for the breakdown and utilization of carbohydrates.

Deficiencies
In the United States, a deficiency of thiamin is rare because refined grains are enriched with this nutrient. Before refined grain products were enriched, a thiamin deficiency could result in a disease called beriberi. Signs of beriberi include loss of appetite, constipation, muscle weakness, pain or tingling in the arms and legs, swelling of the feet, mental depression, memory problems, shortness of breath, and fast heartbeat. Thiamin deficiency does occur in alcoholics because of impaired absorption.

Excesses
In some people an excessive intake can cause an allergic reaction. For most people, the body excretes the excess consumed. Extra thiamin does not boost your energy level. The Tolerable Upper Intake Level has not been determined due to a lack of data concerning adverse effects.

Amount Needed
Adult males need 1.2 milligrams of thiamin each day and adult females need 1.1 milligrams daily.

Food Sources
The best food sources of thiamin include pork, peas, liver, and wheat germ. Good sources include whole-grain and enriched grain products, such as bread, rice, pasta, tortillas, and fortified cereals. Fair sources include pineapple, citrus fruits, milk, spinach, tomatoes, bananas, beans, nuts, seeds, and peanuts.

Riboflavin (vitamin B-2)

Functions
Riboflavin is involved in several vital metabolic processes in the body. It is necessary for normal cell and tissue function. Riboflavin is needed for normal protein and energy metabolism.

Deficiencies
A deficiency of riboflavin rarely occurs except in the severely malnourished. Symptoms can include eye disorders, dry and flaky skin, sores at the corners of the mouth, a sore, red swollen tongue, throat swelling, and anemia.

Excesses
There are currently no reports that indicate problems associated with an excessive intake of riboflavin.

Amount Needed
Healthy, adult males need 1.3 milligrams of riboflavin daily and females need 1.1 milligrams daily.

Food Sources
The best food sources of riboflavin include liver, milk, cottage cheese and other dairy products. Good sources include eggs and meats. Fair sources are whole grains, enriched grains, green leafy vegetables, asparagus, broccoli, beans, and peas. Ultraviolet light, including sunlight, can quickly destroy riboflavin. That’s why milk is stored in opaque plastic or cardboard containers, not clear glass.

Niacin

Functions
Niacin helps the body to metabolize and release the energy in carbohydrates and fats. It is involved with the making of protein and fat. Niacin helps promote healthy cells, gastro-intestinal tract, skin, and nervous system.

Deficiencies
Pellagra is a disease that develops due to a deficiency of niacin. Symptoms include skin problems, diarrhea, dementia, and depression.

Excesses
An excessive intake of niacin can cause tingling and flushing of the skin, itching, digestive upsets, low blood pressure, abdominal pain, liver problems, and ulcers. Large doses of niacin have been used along with medication to help lower cholesterol levels. Speak with your physician before ever starting such a treatment plan. The Tolerable Upper Intake Level is 35 milligrams daily for both adult males and females.

Amount Needed
Niacin recommendations are given in niacin equivalents (NE). This is because niacin comes from two sources: (1) niacin found in food and (2) the amino acid tryptophan which can be converted to niacin in the body. 1 milligram of niacin equals 60 milligrams of tryptophan. The recommended intake of niacin (as NE) is 16 milligrams daily for adult males and 14 milligrams for adult females.

Food Sources
The best sources of niacin include meats, poultry, and fish. Good sources include mushrooms, peanuts, legumes, and nuts. Fair sources include enriched grain products. Niacin is also produced in the body from the amino acid tryptophan.

Pyridoxine (vitamin B-6)

Functions
Pyridoxine is necessary for the normal breakdown of protein, carbohydrates, and fat. It helps turn the amino acid tryptophan into niacin and serotonin. Serotonin is a messenger in the brain. Niacin also helps produce body chemicals such as insulin, antibodies, and hemoglobin.

Deficiencies
A lack of pyridoxine may lead to anemia or weak blood, depression, nerve damage, seizures, greasy, flaky skin problems, and sores in the mouth.

Excesses
At extremely high doses, nervous system damage can occur. The Tolerable Upper Intake Level is 100 milligrams for both adult males and females.

Amount Needed
The recommended intake for adult males is 1.3 milligrams during the ages of 19-50. From age 51 and above, the amount is 1.7 milligrams. The recommended intake for adult females is 1.3 milligrams during the ages of 19-50. From age 51 and above, the amount is 1.5 milligrams each day.

Food Sources
The best food sources of pyridoxine are blackstrap molasses, wheat bran and germ, soybeans, and brown rice. Good sources include organ meats, veal, lamb, chicken, fish, and pork. Fair sources include bananas, lima beans, cabbage, corn, oats, carrots, potatoes, and legumes.

Folic Acid (folacin or folate)

Functions
Folic acid is necessary for strong, healthy blood by helping to form hemoglobin. It plays a role in making new cells. By synthesizing the essential nucleic acids, DNA and RNA, normal cell division and replication occurs.

Deficiencies
A lack of folic acid produces poorly formed blood cells that cannot carry as much oxygen. A deficiency can affect normal cell division and impair growth. Pregnant women who do not get enough folic acid prior to conception and during the first trimester have a greater risk of having a baby with neural tube defects such as spina bifida.

Excesses
Consuming too much folic acid can mask a vitamin B-12 deficiency. An excess can also interfere with some medications. Sleep disturbances are possible as well as irritability. The Tolerable Upper Limit Level is 1,000 micrograms daily for both adult males and females.
Amount Needed The recommended intake of folic acid for adult males and females is 400 micrograms daily.

Food Sources
The best food sources of folic acid include liver, and green leafy vegetables. Good sources include lima beans, asparagus, broccoli, nuts, whole grains, fortified bread, rice, macaroni, noodles, cereals, oranges and orange juice, and lentils.

Vitamin B-12 (cobalamin)

Functions
Vitamin B-12 works closely with folic acid to make red blood cells. Vitamin B-12 is necessary for a healthy nervous system. It helps the body to use fat acids and some amino acids.

Deficiencies
A lack of vitamin B-12 may lead to anemia, fatigue, nerve damage, stomach problems, a smooth tongue, or very sensitive skin. A vitamin B-12 deficiency can be masked by taking extra folic acid. Some people have a medical problem called pernicious anemia in which vitamin B-12 is not absorbed from the intestines properly. They are missing a body chemical called intrinsic factor that comes from the stomach lining. Others have a diseased intestine or have had a large part of their stomachs or intestines removed. These conditions require treatment with vitamin B-12 injections. Strict vegetarians, who eat no animal products, are at risk for developing a vitamin B-12 deficiency. The elderly are also at risk for vitamin B-12 deficiency since 10-30% absorb food-bound vitamin B-12 poorly. If not managed, this could cause severe anemia and irreversible nerve damage. It is important to include a variety of vitamin B-12 fortified foods or a dietary supplement to prevent these problems.

Excesses
There are no known symptoms of taking excessive amounts of vitamin B-12. Extra vitamin B-12 does not boost energy levels. A Tolerable Upper Intake Level has not yet been determined due to a lack of data of adverse effects.

Amount Needed
Adult males and females need 2.4 micrograms of vitamin B-12 daily.

Food Sources
The best sources of vitamin B-12 include animal products, such as organ meats, beef, pork, fish, poultry, eggs, milk, and other dairy foods. Some foods are fortified with vitamin B-12 and are fair sources.

Biotin

Functions
Biotin helps produce energy in your cells. It helps metabolize protein, fat and carbohydrates. Biotin is required by the body in order for four specific enzymes to function properly in metabolism.

Deficiencies
A biotin deficiency is extremely rare in people who eat a healthy diet. In rare cases, these symptoms may appear: heart abnormalities, appetite loss, fatigue, depression, dry skin, low blood sugar between meals, acidic blood, and high blood ammonia. A chemical in raw egg whites prevents the body from absorbing biotin. This problem is prevented by cooking eggs, which destroys avidins ability to bind the biotin.

Excesses
There are currently no reported effects of consuming excess amounts of biotin. Therefore the Tolerable Upper Intake Level has not been determined.

Amount Needed
The recommended intake for both adult males and females is 30 micrograms daily.

Food Sources
Biotin is found in a variety of foods. Good sources include eggs, liver, yeast breads, cereals, chocolate, peanuts, cauliflower, nuts, peas, and mushrooms. Fair food sources include milk. Biotin is also produced by the bacteria naturally found in the intestines.

Pantothenic Acid

Functions
Pantothenic acid helps with the breakdown and utilization of carbohydrates, proteins, and fats. It also helps the body produce energy in the cells. Pantothenic acid is involved in antibody production, adrenal activity, growth and metabolism.

Deficiencies
A deficiency of pantothenic acid is rarely a problem for those who eat a healthy diet.

Excesses
The only symptoms of excessive intake are occasional diarrhea and water retention. An excess may trigger a thiamine deficiency. No Tolerable Upper Intake Level has been determined for pantothenic acid due to a lack of data on adverse effects.

Amount Needed
The amount needed by both adult males and females is 5 milligrams daily.

Food Sources
Pantothenic acid is found widespread in plant and animal foods. Meat, poultry, fish, whole-grain products, legumes, and eggs are considered the best sources. Good sources include broccoli, cauliflower, mushrooms, bran, sweet potatoes, potatoes, lima beans, soybeans, peanuts, peas, oatmeal, and cheese.

Vitamin C

Functions
Vitamin C forms collagen, a connective tissue, which gives strength and structure by holding together muscles, bones, and other tissues. It helps to build, repair, and maintain red blood cells, bones, and other tissues. It gives strength and flexibility to blood vessels and capillary walls. This helps to prevent bruising. It helps the body to absorb iron found in plant foods. Vitamin C is necessary for cuts and wounds to heal. It keeps the gums healthy and protects you from infection by keeping the immune system strong and healthy.

Deficiencies
A lack of vitamin C can lead to a disease called scurvy. Scurvy causes muscle weakness, swollen and bleeding gums, loss of teeth, bleeding under the skin, bruising, poor wound healing, tiredness, and depression.

Excesses
Vitamin C is water-soluble, so the body excretes any excess consumed. However, very large doses may cause kidney stones and diarrhea. The Tolerable Upper Intake Level is 2,000 milligrams for both adult males and females.

Amount Needed
Adult males need 90 milligrams of vitamin C daily and adult females need 75 milligrams daily. People who smoke need about twice as much vitamin C daily.

Food Sources
The best sources of vitamin C include citrus fruits (oranges, grapefruits, tangerines), strawberries, peppers, kiwi, and cantaloupe. Good sources include some green-leafy vegetables, cauliflower, tomatoes, potatoes, and pineapple.