What are vitamins and why are they important?
Vitamins are organic substances that are essential for the proper growth and functioning of the body. Unlike protein, fat, and carbohydrates, vitamins provide no calories. However, they are necessary (in small amounts) for normal chemical reactions (metabolism) inside the body. Vitamins must be obtained from food because the body cannot produce them. (The exception is vitamin D, which can be produced by the skin when it is exposed to the sun). If the intake of vitamin(s) is insufficient due to poor nutrition, restricted diets, or inadequate intestinal absorption of the vitamins, diseases can occur.

Examples of diseases caused by vitamin deficiencies (please see Table 1) include anemia (due to deficiencies of folic acid and vitamin B12), nerve and brain damage (due to deficiencies of thiamin and vitamin B12), easy and excessive bleeding (due to deficiency of vitamin K), impaired night vision and blindness (due to deficiency of vitamin A), bone diseases (due to deficiency of vitamin D or calcium), and scurvy (due to deficiency of vitamin C). These vitamin deficiency diseases are rare in the western societies, and occur mainly in areas of the world where people have very poor diets.

The Food and Nutrition Board of the National Academy of Sciences has published the Recommended Dietary Allowance (RDA, also popularly referred to as Recommended Daily Allowance) for vitamin and mineral consumption. The RDAs represent the amounts of daily vitamin intake necessary to prevent vitamin deficiency diseases. An average person in the United States should be able to obtain all the vitamins to meet the RDAs from a balanced diet. Therefore, a healthy person eating a balanced diet should not require vitamin supplements.

However, vitamin deficiencies in the United States (please see Table 2) can still occur in certain populations. For example vitamin D deficiency is common among the elderly due to a combination of inadequate oral intake of vitamin D and lack of sun exposure. Vitamin B-12 deficiency can occur in patients with pernicious anemia and in elderly patients with atrophic gastritis (conditions where the patients are unable to absorb B-12 from the diet). Alcoholics can develop deficiency of thiamine, folic acid, and niacin. Patients taking orlistat, Xenical for weight reduction may not absorb fat and can develop vitamin deficiencies that normally dissolve in fat (the fat soluble vitamins A,D,E,K).

Furthermore, scientists have discovered that inadequate intake of certain vitamins can cause diseases NOT traditionally attributed to vitamin deficiency. For example, inadequate intake of folic acid and vitamin B-6 and B-12 is associated with elevated blood levels of homocysteine, and increased risk of heart attacks. Inadequate folic acid intake in women of childbearing age increases the risk of birth defects. Therefore even though gross vitamin deficiency diseases are rare in the United States, vitamin supplements are recommended in this country to prevent vitamin deficiency in special populations and to prevent diseases such as atherosclerosis, heart attack, strokes, birth defects, and perhaps certain cancers.

Calcium and Vitamin D

What is calcium and vitamin D, and what does it do?

• Calcium is a building block for bone. Adequate dietary calcium intake is one of the important factors for maintaining healthy and strong bones. But an average woman in the United States consumes less than 500 milligrams of calcium per day in her diet, which is less than the recommended amount.
• Vitamin D is necessary for the intestines to absorb dietary calcium. Vitamin D comes from food and is also produced by the skin upon exposure to sunlight. Active children and young adults living in sunny regions (Southern California, Hawaii, countries around the equator, etc.) can produce most of the vitamin D they need from their skin. But in the northern United States, there is insufficient sunlight during the winter for adequate vitamin D production by the skin. And vitamin D deficiency is common among elderly individuals.

What are adverse consequences of inadequate calcium intake and low vitamin D?

• Inadequate calcium intake contributes to osteoporosis. Patients with osteoporosis have weak bones that can fracture with minimal trauma. For example, patients with osteoporosis can suffer bone fractures with minor falls or just stepping off a curb.
• Children with prolonged vitamin D deficiency can develop rickets. Children with rickets will develop bowing of the extremities due to weak bones. In adults, vitamin D deficiency can lead to osteoporosis and osteomalacia (both conditions of weakened bones).

What are recommendations for adequate calcium and vitamin D intake?

The National Institutes of Health Consensus Conference on Osteoporosis recommend the following calcium intake:

1. 800 mg/day for children ages 1 to 10
2. 1000 mg/day for men, premenopausal women, and postmenopausal women also taking estrogen
3. 1200 mg/day for teenagers and young adults ages 11 to 24
4. 1500 mg/day for post menopausal women not taking estrogen
5. 1200mg to 1500 mg/day for pregnant women and nursing mothers
6. The total daily intake of calcium should not exceed 2000 mg.

The Food and Nutrition Board of the Institute of Medicine recommended the following vitamin D intake:

1. 200 IU daily for men and women 19 to 50 years old
2. 400 IU daily for men and women 51 to 70 years old
3. 600 IU daily for men and women 71 years and older

An average multivitamin contains 400 IU of vitamin D. Vitamin D rich foods include:

• fortified milk,
• herring,
• salmon, and;
• fish liver oils

Vitamin D deficiency is common among the elderly living in the northern states, therefore, it is recommended that the elderly take a multivitamin daily, eat vitamin D rich foods, and have regular sun exposure (several times a week with sunscreen) in the spring, summer and fall.

For patients with established osteoporosis, the recommended dose of vitamin D is 400 IU twice a day. For example, they can take combination pill that contains calcium 500mg and vitamin D 400IU twice a day.

Precaution:

• Excessive vitamin D leads to elevated blood calcium levels, which can cause significant toxicity. Symptoms of vitamin D toxicity include loss of appetite, nausea, vomiting, thirst, excessive urination, muscular weakness, and in severe cases, coma. Consequently, intake should not exceed 1000 IU daily.
• While adequate calcium intake and vitamin D levels are important to maintain bone strength, they are not always sufficient to fully protect against the rapid bone loss that can occur around the time of menopause. Estrogen replacement therapy, and medications that strength bone may also be necessary, especially among postmenopausal women.

What is Folic Acid?

What is folic acid and what does it do?

Folic acid is a synthetic chemical that has the same biological effects as folate. Folate and folic acid are B vitamins important in the synthesis of DNA (genetic material inside cells) and in the break down of homocysteine (an amino acid that can cause blood vessel damage).

Folic acid is more reliably absorbed than folate. Therefore folic acid rather than folate is used in vitamin supplements and is added to cereals, breads, and pasta (adding nutrients to food to prevent deficiency is called fortification).

What foods are rich in folates and folic acid?

Folates are found in green leafy vegetables (such as asparagus, and spinach), fruits (such as oranges and orange juice), garbanzo beans, lima beans, lentils, eggs, and meats. Folic acid is also found in fortified cereals, pasta, and bread.

What are the adverse consequences of inadequate folic acid intake?

• Gross (severe) folate deficiency can cause anemia. In the United States for example, gross folate deficiency can occur due to poor diet and diminished absorption among alcoholics.
• Mild folate deficiency (usually due to lack of folic acid supplement intake) in healthy women is associated with an increased risk of spina bifida (a form of birth defect) in newborn infants.
• Studies have shown that low blood folate levels are associated with high blood homocysteine levels. High blood levels of homocysteine can damage the inner surface of blood vessels, promote blood clotting, accelerate atherosclerosis, and thus lead to heart attacks and strokes.

What are the benefits of taking folic acid supplements?

• Taking folic acid supplements starting before pregnancy can significantly reduce the risk of neural tube birth defects.
• Higher folic acid intake and high blood folate levels are associated with lower blood homocysteine levels and lower heart attack risks. In a large population study involving women, those who had the highest consumption of folic acid (usually in the form of multivitamins) had fewer heart attacks than those who consumed the least amount of folic acid. However, there is not yet conclusive scientific proof that taking folic acid supplements will decrease heart attacks or strokes.
• Studies have shown that regular moderate alcohol intake increases the risk of developing colon and breast cancers. Studies have also shown that increased folic acid intake may reverse the increased cancer risks related to regular alcohol intake. Alcohol interferes with the absorption and metabolism of folate, and folate is important in maintaining and repairing damages to DNA. Damage to DNA is believed to lead to cancer formation.

What is the toxicity of folic acid?

Folic acid is water soluble and rapidly excreted in the urine, and has no known toxicity.

Who should consider taking folic acid supplements?

• Since adequate folate levels in the body is important in early pregnancy (often before women are aware that they are pregnant) to prevent neural tube birth defects, women in childbearing years are recommended to take a supplement that contains 400 micrograms of folic acid daily, before they become pregnant. Women with certain seizure disorders may need higher doses of folic acid during early pregnancy to prevent neural tube defects.
• All healthy adults are recommended to take a multivitamin that contains 400 mcg of folic acid daily. Even though there is not yet conclusive proof that taking folic acid supplements prevent heart attacks or strokes, taking one multivitamin a day is safe long-term. Thus the potential benefit of lowering homocysteine levels outweighs the risk.
• Patients with early onset of heart attacks and other forms of coronary heart disease associated with elevated blood homocysteine levels should consult their doctors. These patients may need higher doses of folic acid supplements (higher than 400 mcg) as well as vitamins B6 and B12 supplements to lower homocysteine levels.
• Patients with folic acid deficiency related to alcoholism or hemolytic anemia (a form of anemia due to excess destruction of red blood cells) may need higher doses of folic acid supplements than 400 mcg/day.

Vitamin E

What is vitamin E and what does it do?

Vitamin E represents a family of eight fat-soluble anti-oxidant vitamins. Alpha-tocopherol is the most important E vitamin in humans. Alpha-tocopherol protects the LDL cholesterol in the blood and body cell membranes from oxidation by free radicals. (Oxidation of LDL cholesterol is believed to contribute to atherosclerosis of the arteries that can lead to strokes and heart attacks.) Alpha-tocopherol also inhibits blood clotting.

What foods are rich in vitamin E?

Foods rich in alpha-tocopherol include green leafy vegetables, carrots, nuts, olive oil, corn oil, canola oil, safflower oil, sunflower oil, wheat germ, whole grains, and margarines made from plant oils. Meats, fruits, and milk have little vitamin E.

What are adverse consequences of inadequate alpha-tocopherol (vitamin E) intake?

Severe vitamin E deficiency can lead to muscle weakness and impaired balance and coordination, and anemia. But there have been no reports of severe vitamin E deficiency among healthy adults. Vitamin E deficiency can occur in children and adults with fat malabsorption (conditions that render their intestines unable to absorb fat and fat soluble vitamins A, D, E, and K).

What are the benefits of vitamin E supplements?

• Oxidation of LDL cholesterol particles can lead to arteriosclerosis and increase the risks of heart attacks and strokes. Vitamin E is an antioxidant that may reduce heart attack risks. However, the value of vitamin E in the prevention of heart attacks and strokes is not yet known. In observational studies involving large numbers of healthy men and women, subjects who consumed more vitamin E had lower rates of heart attacks than subjects who consumed less vitamin E. But the results from observational studies are not as scientifically valid as randomized, placebo controlled trials. In randomized controlled trials involving patients with existing coronary heart disease (for example, patients who have already suffered heart attacks), the benefit of vitamin E is inconsistent. Several studies have shown that taking alpha-tocopherol supplements (400-800 IU) can reduce heart attacks, but several other studies have shown no benefit of alpha-tocopherol in preventing heart attacks. Thus, additional large-scale, prospective, placebo-controlled trials are needed.
• Some cancers develop from oxidation damage to DNA. In the Alpha-Tocopherol Beta Carotene (ATBC) study scientists found a 32% reduction in the incidence of prostate cancer among subjects taking alpha-tocopherol supplements compared to those not taking the vitamin. However, several studies have found no benefit of vitamin E in preventing lung and breast cancers. More randomized controlled trials are needed to determine the effect of vitamin E on cancer risks.
• Alzheimer's disease is a degenerative brain disease with progressive loss of mental capacity, thought in part be due to oxidation. High doses of alpha- tocopherol supplementation in one study slowed the progression of Alzheimer's disease. Although these results are promising, large scale, placebo controlled, prospective trials will be required to determine the role of a-tocopherol supplementation in the treatment of Alzheimer's disease.

What is the toxicity of vitamin E?

Vitamin E in high doses can impair blood clotting and increase the risks of hemorrhage. Vitamin E can also increase the blood thinning action of warfarin, Coumadin (an anti-coagulant used in preventing blood clotting) and increase the risk of bleeding in patients taking Coumadin. Therefore, patients taking Coumadin, patients with vitamin K deficiency, and patients taking other medications that impair platelet function should take vitamin E supplements under a doctor's supervision.

Who should consider using vitamin E (alpha-tocopherol) supplements?

• All adults are recommended to eat vitamin E rich foods and to take a multivitamin daily. (An average multivitamin tablet contains 30-40 IU of vitamin E).
• Consult your doctor regarding additional vitamin E supplements. For example some doctors recommend supplementation of 400 IU of vitamin E for all healthy middle age or older adults to prevent strokes, heart attacks, and cancers. Others recommend vitamin E supplements (400 IU) only for patients with small dense LDL cholesterol particles and with familial hypercholesterolemia. These patients are susceptible to oxidation and have higher than normal risks of heart attacks.

Vitamin A

What is vitamin A and what does it do?

Vitamin A represents a number of related compounds; retinol, retinal, retinoic acid, and a vitamin A precursor beta (b)-carotene. Vitamin A is important for night vision, for fighting against infection (body immunity), and in regulating the genes to make sure they function properly.

What foods are rich in vitamin A?

Orange and yellow vegetables such as carrots, cod liver oil, fortified cereal, cantaloupe, whole milk, spinach, eggs are examples of vitamin A rich foods.

What are adverse consequences of inadequate vitamin A intake?

Early vitamin A deficiency leads to impaired night vision, and advanced vitamin A deficiency can lead to corneal ulcers and scarring and blindness. In developing countries vitamin A deficiency is an important cause of blindness among children. Children with vitamin A deficiency are also more likely to develop diarrhea and respiratory infections than children who are not vitamin A deficient. Vitamin A deficiency is rare among healthy adults in the United States.

What are the benefits of vitamin A supplements?

There is NO evidence that taking vitamin A supplements can prevent cancer or heart attacks. In the ATBC trial, subjects given beta-carotene had higher incidence of lung cancer than subjects not given beta-carotene.

What is the toxicity of vitamin A?

Vitamin A can be toxic in high doses (Usually 10 times RDA). Symptoms of vitamin A toxicity include nausea, dry itchy skin, headache, and loss of appetite, bone and joint pain. High doses of vitamin A can also cause liver toxicity. Elderly people and people who drink alcohol heavily are more susceptible to vitamin A toxicity.

Vitamin A in relatively low doses (only several times RDA) can cause birth defects when given to pregnant women.

What are recommendations regarding vitamin A supplements?

• Eat a balanced diet and take one multivitamin daily. (Most multivitamins contain 5000 IU of vitamin A, generally in the form of beta-carotene).
• Additional vitamin A supplements are currently NOT recommended.
• Pregnant women should not take additional vitamin A supplements without doctor supervision. Pregnant women should also avoid skin acne medications derived from natural and synthetic retinoids such as tretinoin (Retin-a), isotretinoin (Accutane), and psoriasis medications such as etretinate and acitretin.

Vitamin C

What is vitamin C and what does it do?

Vitamin C, also known as ascorbic acid, is a water-soluble anti-oxidant vitamin. Vitamin C is required for the synthesis of collagen and dentin. Collagen is the structural component of blood vessels, bones, ligaments, and tendons, while dentin is the structural component of teeth. Vitamin C is also an effective antioxidant that protects proteins and genetic materials (RNA and DNA) from damage by free radicals.

What foods are rich in vitamin C?

Foods rich in vitamin C include fruits and vegetables such as oranges, grapefruit, broccoli, spinach, tomatoes, potatoes, strawberries, and sweet red peppers.

What are the adverse consequences of vitamin C deficiency?

Severe vitamin C deficiency causes scurvy. Symptoms of scurvy are related to weakening of the collagen in tissues, bones and blood vessels; they include easy bruising, hair and tooth loss, poor wound healing, joint pain and swelling, swollen and bleeding gums, and fatigue. Since a normal diet of fresh fruits and vegetables contain many times the amount of vitamin C (10mg/day) necessary to prevent scurvy, scurvy is rare in the United States, but can occur in developing countries where the diet is severely deficient in vitamin C.

What are the benefits of taking vitamin C supplements?

• Oxidation of LDL cholesterol particles is believed to play a role in atherosclerosis that can lead to heart attacks and strokes. Antioxidants such as vitamins E and C are believed to combat oxidation and retard the development of atherosclerosis. But the studies on the benefit of vitamin C in preventing heart attacks in healthy subjects and in subjects who have already had heart attacks have yielded conflicting results. Thus the role of vitamin C supplements in preventing heart attacks and strokes are uncertain.
• Studies have shown that increased consumption of fresh fruits and vegetables is associated with reduced cancer rates. The vitamin C in fresh fruits and vegetables are believed in part to be responsible for this benefit. But the role of vitamin C supplements in preventing cancers is not clear. Some studies have shown that higher intakes of vitamin C are associated with decreased incidence of cancers of the mouth, throat, stomach, colon, and lung. However, several large prospective studies found no benefit of long-term vitamin C supplement use in decreasing breast cancer rate. Studies using vitamin C supplements did not decrease the occurrence of stomach cancer.
• Linus Pauling advocated using large doses (>1 gram/day) of vitamin C to prevent the common cold. But research on large doses of vitamin C showed no significant effect on the incidence of the common cold. It is also unclear whether large doses of vitamin C decrease the duration of cold symptoms.

What is the toxicity of vitamin C supplements?

Vitamin C is generally safe. Large doses of vitamin C may cause stomach upset in adults and have been reported to cause kidney stones. Large doses of vitamin C may also cause hemolysis (destruction of red blood cells resulting in anemia) in patients who are born with a deficiency in an enzyme G6PD (glucose-6-phosphate dehydrogenase).

Large doses of vitamin C may interfere with the blood thinning action of warfarin, Coumadin (a medication commonly used to prevent blood clots). Therefore patients on Coumadin should not take large doses of vitamin C without doctor supervision and monitoring.

Who should consider using vitamin C supplements?

• Healthy adults should not require vitamin C supplements. Healthy adults should eat 5 servings/day of fresh fruits and vegetables along with one multivitamin (an average multivitamin contains 60 mg of vitamin C) daily. Fresh fruits and vegetables not only are rich sources of vitamin C but also contain other beneficial antioxidants and cancer-fighting phytochemicals.
• The following individuals need to pay special attention to eating more fresh vegetables and fruits: 1) elderly individuals sometimes have insufficient vitamin C intake, 2) subjects on estrogen-containing birth control pills can have lower vitamin C levels in blood, and 3) subjects taking aspirin regularly can have lower vitamin C levels in blood due to increasing urinary excretion of vitamin C.
• Individuals taking iron supplements for iron deficiency anemia are often instructed to take vitamin C, either as a supplement or as orange juice, to enhance the absorption of iron. This is common in childbearing age women.

Vitamin B-12

What is vitamin B-12 and what does it do?

Vitamin B-12 is a vitamin that contains a metal called cobalt. Cyanocobalamine is the form of vitamin B-12 used in most supplements. Cyanocobalamin is readily converted to active forms of vitamin B-12 in the body. Vitamin B-12 is necessary for the enzymatic conversion of homocysteine to methionine. Lack of vitamin B-12, like lack of folate, can lead to high blood levels of homocysteine. Vitamin B-12 and folate are both necessary for the production of DNA (genetic materials inside cells).

What are the adverse consequences of vitamin B-12 deficiency?

• Vitamin B-12 deficiency, like folate deficiency, can lead to impaired bone marrow production of red blood cells, leading to megaloblastic anemia (anemia with large sized but diminished number of hemoglobin-poor red blood cells).
• Vitamin B-12 deficiency, like folate deficiency, can lead to high homocysteine levels in the blood. High blood levels of homocysteine are associated with heart attacks and strokes.
• Vitamin B-12 deficiency can cause irreversible neurological (nerve and brain) damage. Symptoms include numbness and tingling of the arms and the legs, difficulty walking, memory loss, disorientation, and diminished mental capacity. Even though megaloblastic anemia and high homocysteine levels can be corrected with vitamin B-12 treatment, the neurological symptoms can be permanent (irreversible).
• Other symptoms of B-12 deficiency include constipation, sore tongue and poor appetite.

What foods are rich in vitamin B-12?

Vitamin B-12 is present in fortified cereals, beef, chicken, turkey, fish, egg, milk, and shellfish such as clams and crab.

Bodily absorption of vitamin B-12 requires 1) stomach acid (and pancreatic enzyme) to digest food and free up the vitamin B-12, and 2) a protein called intrinsic factor (IF) to bind to vitamin B-12 before the small intestine can absorb the vitamin into the body.

Thus patients with diminished stomach acid production (pernicious anemia or atrophic gastritis or chronically taking proton pump inhibitors), diseases of the small intestine (celiac sprue) or pancreas (chronic pancreatitis), or diseases that inactivate intrinsic factor (pernicious anemia) can develop vitamin B-12 deficiency.

What are the benefits of Vitamin B-12 supplements?

Folic acid, B-6 and B-12 supplements (at doses higher than RDA) have been prescribed by some doctors to lower high blood homocysteine levels in patients with early onset of coronary heart disease.

What is the toxicity of vitamin B-12?

There are no reports of vitamin B-12 toxicity with large doses. For example, 1,000 mcg (1mg) monthly injections have been used to treat B-12 deficiency in pernicious anemia without any side effects. However, for healthy individuals large doses of vitamin B-12 is not recommended.

Who should consider vitamin B 12 supplements?

Healthy adults should be able to obtain the vitamin B-12 from a balanced diet. Healthy adults are recommended to take one multivitamin daily that contains vitamin B-12. Taking a multivitamin daily is especially important for individuals at risk of developing vitamin B-12 deficiency such as:

• All elderly individuals are recommended to take one multivitamin daily that contains vitamin B-12. This is because atrophic gastritis is common among the elderly. Furthermore, many are unaware that they have atrophic gastritis because the condition usually does not cause pain or other symptoms.
• Since vitamin B-12 is found only in foods of animal origin, a strict vegetarian diet without any animal meat or products can result in vitamin B-12 deficiency, unless he/she uses a multivitamin daily that contains B-12.

The following individuals can develop vitamin B-12 deficiency and should be under the care a doctor:

• Patients with pernicious anemia cannot absorb vitamin B-12 from food or oral supplements, hence B-12 injections are usually required to correct megaloblastic anemia and to prevent irreversible neurological damage. Patients with pernicious anemia cannot produce stomach acid because their own antibodies have destroyed their acid producing cells in the stomach. Pernicious anemia patients also have antibodies that inactivate intrinsic factor.
• Patients who have had surgical removal of the stomach cannot produce stomach acid or intrinsic factor to absorb vitamin B-12 from food or supplements.
• Patients with extensive resection of the small bowel may not be able to absorb vitamin B-12 from food and supplements.
• Patients with celiac sprue (a condition of food allergy to gluten that leads to atrophy of the small bowel lining) may also not be able to absorb vitamin B-12 from food and supplements.
• Pancreatic insufficiency (most often as a result of chronic pancreatitis) can also lead to vitamin B-12 deficiency.
• Patients taking metformin, Glucophage (a medication used to control blood glucose levels in patients with type II diabetes), and cholestyramine, Questran (a medications used to lower cholesterol in blood and also sometimes used to control unexplained diarrhea) can also decrease the absorption of vitamin B-12 from food.

Vitamin B-6

What is vitamin B-6 and what does it do?

Vitamin B-6 is a water-soluble vitamin that exists in three forms; pyridoxine, pyridoxal, and pyridoxamine. Pyridoxine is the form most used in vitamin supplements. Vitamin B-6 is important in the synthesis of heme. Heme is a component of hemoglobin. Hemoglobin is the oxygen-transporting chemical inside red blood cells. Vitamin B-6 is also important for the synthesis of neurotransmitters (chemicals such as serotonin, dopamine, norepinephrine, and gamma-aminobutyric acid that carry electrical signals in between nerves). Adequate levels of neurotransmitters in the brain are important for good mood and mental capacity. Vitamin B-6 is necessary for the chemical conversion of homocysteine to cysteine.

What are the adverse consequences of vitamin B-6 deficiency?

Severe deficiency of vitamin B-6 is uncommon. Alcoholics and patients with severe diarrhea syndromes may be at risk of vitamin B-6 deficiency. Symptoms of severe vitamin B-6 deficiency include depression, nerve damage (peripheral neuropathy), sores of the mouth, and scaliness around the mouth, nose, and eyes. Advanced vitamin B-6 deficiency can lead to seizures and severe anemia.

Mild vitamin B-6 deficiency is associated with elevated homocysteine blood levels. High levels of homocysteine are associated with increased risk of heart attacks and strokes. Mild deficiency may be associated with depression. In the elderly, mild deficiency may be associated with diminished mental capacity and worsening of symptoms of Alzheimer's disease.

What are the benefits of vitamin B-6 supplements?

• The level of homocysteine in the blood is affected by folic acid, vitamin B-12, and vitamin B-6. Low vitamin B-6 intake (like low folic acid and vitamin B-12 intake) is associated with increased blood homocysteine levels and increased risk of heart attacks. Studies have found that individuals with higher intake of vitamin B-6 and higher blood vitamin B-6 levels have lower risk of heart disease than those with lower intake and lower vitamin B-6 blood levels.
• High doses of vitamin B-6 have been prescribed to relieve symptoms of many conditions such as: 1) women who experience depression while taking oral birth control pills, 2) women with symptoms of PMS such as moodiness, fatigue fluid retention, and irritability, 3) patients experiencing pain, numbness, and weakness of the hands and fingers due to carpal tunnel syndrome. Unfortunately, studies have demonstrated either no benefit or weak benefit of vitamin B-6 in these situations.

What foods are rich in vitamin B-6?

Examples of foods rich in vitamin B-6 include meats (chicken, turkey), bananas, avocadoes, fortified cereal, potatoes, and hazelnuts.

What is the toxicity of vitamin B-6?

High doses of vitamin B-6 (usually at doses of 500mg-1000 mg/day or higher) may cause sensory nerve damage resulting in pain and numbness of the extremities. But neurological symptoms have been reported in women taking only 50 mg/day of vitamin B-6 for PMS.

High doses of vitamin B-6 have been found to decrease the effectiveness of Dilantin and Phenobarbital, medications used in preventing and treating seizures. Vitamin B-6 can also decrease the effectiveness of levodopa, a medication used to treat Parkinsonism.

Who should consider vitamin B-6 supplements?

All adults are encouraged to eat a balanced diet and take a multivitamin daily. Surveys have found that many elderly individuals are not taking enough vitamin B-6 in their diets. Thus it is especially important that elderly individuals take a multivitamin daily. Additional vitamin B-6 supplements are usually not necessary except in the following situations:

• Medications such as isoniazid (anti-tuberculosis), cycloserine, and penicillamine, can cause vitamin B-6 deficiency. Patients taking these medications should be under the care of doctors. The doctor may prescribe vitamin B-6 supplements to prevent sensory nerve damage related to B-6 deficiency.
• Folic acid, B-6 and B-12 supplements (at doses higher than RDA) have been prescribed by some doctors to lower high blood homocysteine levels in patients with early onset of coronary heart disease.

Summary: What are general guidelines for vitamin supplements based on available data?

• Eat at least 5 servings of vegetables and fruits daily. Fruits and vegetables are high in fiber and are rich in vitamin C and other antioxidant vitamins.
• Women in childbearing years should take a multivitamin that contains at least 400 micrograms of folic acid daily for the prevention of neural tube birth defects.
• Adults and elderly should take one multivitamin daily. One multivitamin a day is safe and inexpensive. The multivitamin should contain 400 micrograms of folic acid, and RDA levels of other vitamins. (The folic acid and vitamins B-6 and B-12 can help lower homocysteine. The vitamin D is important in preventing and treating osteoporosis).
• People with an inadequate amount of calcium in their diet should consider calcium supplements.
• Eat less cholesterol and saturated fats, stop smoking cigarettes, control high blood pressure and diabetes, lose excess weight, and exercise regularly.
• Adults should check their blood cholesterol profile (LDL cholesterol, HDL cholesterol).
• Vitamin E (400 IU/day) is recommended for patients with small LDL cholesterol particles and elevated Lp(a) cholesterol to help decrease oxidation of these cholesterol particles. Vitamin E may also prevent prostate cancer.
• Patients with an early onset of atherosclerosis and heart attacks should check their blood levels of homocysteine. (Normal levels of blood homocysteine are 6- 10umol/liter for women and 8-12 umol/liter for men). A doctor experienced in treating coronary heart disease should supervise the treatment of hyperhomocysteinemia because treatment may involve using higher doses of folic acid and vitamins B-6 and B-12 than RDA.

Table I - Vitamin deficiency syndromes

The deficient vitamin	Syndrome	Symptoms/Signs
A	Xerophthalmia	Dry skin, dry eyes, and blindness in advanced cases
D	Osteomalacia	Weak and deformed bones
K	Hypoprothrombinemia	Decreased blood clotting factors, leading to increased risk of bleeding
E		Anemia
C	Scurvy	Weakened tissues and bleeding
Thiamin	Beriberi	Brain, nerve, and heart damage
Niacin	Pellagra	Skin inflammation, diarrhea, dementia, and nerve damage
Folic acid		Anemia
B12		Anemia, nerve damage, and dementia

Table II - Diseases and conditions that can cause vitamin deficiencies in theUS

Alcoholics with poor nutrition can develop thiamin, niacin, and folic acid deficiency.

Patients lacking pancreatic digestive enzymes (usually due to chronic pancreas damage from alcohol abuse or cystic fibrosis) cannot digest and absorb fat. Consequently, they cannot absorb those vitamins (A, D, E, and K) that rely on fat for their proper absorption (fat-soluble vitamins).

Patients with small intestine disorders (such as celiac sprue) also cannot absorb fat and the fat-soluble vitamins A, D, E, and K.

Patients with pernicious anemia do not have the necessary protein in the stomach to absorb vitamin B12.

Patients with Crohn's disease involving the small intestine (Crohn's ileitis) or who have undergone small intestine resection may not be able to absorb vitamin B12.

Strict vegetarians who consume no animal products can develop B12 deficiency since there is a lack of B12 in vegetables.

Elderly individuals that are housebound can develop bone disease due to lack of vitamin D because of a combination of inadequate dietary intake and lack of sun exposure.

ProfitMTFuture ™. Copyright 2005-2006©