vitamins

Vitamins

1. Vitamin A
  • Found in animal foods and converted from beta-carotene in plant foods.
  • Required for vision, gene expression, reproduction, embryonic development, red blood cell production, and immune function.
  • Prescription vitamin A derivatives are used to treat skin conditions (acne) and retinitis pigmentosa (genetic eye disease).
  • Deficiency is rare in Canada, but common in developing countries due to malnutrition. It causes night blindness, dry eyes and skin, and impaired growth.
  • Drugs that deplete vitamin A: cholestyramine, colestipol, mineral oil, and neomycin.
  • Supplements should be avoided by those at risk of lung cancer (smokers) or liver toxicity (alcoholics, liver disease).
  • Doses greater than 10,000 IU daily should be avoided by pregnant women due to the risk of birth defects. Most prenatal vitamins provide 5,000 IU.
  • Doses greater than 5,000 IU may increase risk of osteoporosis.
  • Supplements of vitamin A beyond what is provided in a multivitamin are not recommended due to risk of toxicity. To avoid this risk, choose a multivitamin that contains beta-carotene, which is converted to vitamin A in the liver, but is not associated with health risks.

  • Food Sources : Liver, dairy products, and oily fi sh (Beta-carotene is found in orange and green vegetables and fruit)
  • Adequate Intake : (mcg/day)
    Men = 900
    Women = 700
    Pregnancy = 770
    Lactation = 1,300
  • Upper Limit : (mcg/day)
    Men = 3,000
    Women = 3,000
    Pregnancy = 3,000
    Lactation = 3,000
    Note: 1 mcg = 3.33 IU
  • Side Effects : Liver toxicity and birth defects (associated with vitamin A, not beta-carotene)
    • 2. Vitamin B1 Thiamine
  • Required for energy production, nerve and muscle function, enzyme reactions, and fatty acid production.
  • Deficiency causes beriberi, a disease that affects cardiovascular, nervous, muscular, and gastrointestinal systems.
  • Deficiency is common in developing countries; in North America it occurs in alcoholics, those with kidney disease, malabsorption syndromes (celiac disease), and in those with poor diets.
  • Drugs that deplete vitamin B1: furosemide, antibiotics, oral contraceptives, and phenytoin.
  • Most people get adequate thiamine from diet and/or a multivitamin.

  • Food Sources : Brewer’s yeast, organ meats, whole grains, legumes, and nuts
  • Adequate Intake : (mg/day)
    Men = 1.2
    Women = 1.1
    Pregnancy = 1.4
    Lactation = 1.4
  • Upper Limit : Not determined
  • Side Effects : No adverse effects known with food or supplements
    • 3. Vitamin B2 Ribofl avin
  • Required for energy metabolism, enzyme reactions, vision, and skin/hair/nail health; functions as an antioxidant; activates vitamin B6, niacin, and folate.
  • May play a role in preventing migraine headaches and cataracts.
  • Defi ciency occurs in alcoholics, the elderly, and those with poor diets.
  • Symptoms of deficiency include sore throat; redness/swelling of the mouth, throat, tongue, lips, and skin; decreased red blood cell count; and blood vessel growth over the eyes. Defi ciency may impair iron absorption and increase risk of pre-eclampsia in pregnant women.
  • Drugs that deplete vitamin B2: antibiotics, chlorpromazine, amitriptyline, adriamycin, and phenobarbitol.
  • Most people get adequate ribofl avin from diet and/or a multivitamin.

  • Food Sources : Dairy, whole grains, meat, eggs, dark green vegetables, fortifi ed cereals
  • Adequate Intake : (mg/day)
    Men = 1.3
    Women = 1.1
    Pregnancy = 1.4
    Lactation = 1.6
  • Upper Limit : Not determined
  • Side Effects : No adverse effects known with food or supplements
    • 4. Vitamin B3 Niacin
  • Required for energy metabolism, enzyme reactions, skin and nerve health, and digestion.
  • High doses of nicotinic acid (3 g daily) can lower cholesterol (reduce LDL and triglycerides and increase HDL) and reduce the risk of heart attack and stroke; high dosages should be supervised by a physician.
  • Deficiency causes pellagra, the symptoms of which are skin rash, diarrhea, dementia, and death.
  • Defi ciency may be caused by poor diet, malabsorption diseases, dialysis, and HIV.
  • Drugs that deplete vitamin B3: antibiotics, isoniazid, and 5-Fluorouracil (chemotherapy).
  • High-dose niacin, taken along with statin drugs (i.e., lovastatin), may increase the risk of rhabdomyolysis (muscle degeneration and kidney disease).
  • Most people get adequate niacin from diet and/or a multivitamin; supplements may be recommended for those with high cholesterol.

  • Food Sources : Fish, meat, poultry, dairy, nuts, seeds, whole grains, fortifi ed cereals
  • Adequate Intake : (mg/day)
    Men = 16
    Women = 14
    Pregnancy = 18
    Lactation = 17
  • Upper Limit : 35 mg/day
  • Side Effects : No adverse effects from niacin in foods; supplements may cause fl ushing and upset stomach; higher doses (500 mg/ day) may cause liver problems, particularly with time-release products
    • 5. Vitamin B5 Pantothenic Acid
  • Required for carbohydrate metabolism, adrenal function, enzyme reactions, and production of fats, cholesterol, bile acids, hormones, neurotransmitters, and red blood cells.
  • Deficiency is rare, except in malnutrition, and causes burning/tingling in hands and feet, fatigue, and headache.
  • Drugs that deplete vitamin B5: oral contraceptives, amitriptyline, imipramine, and desipramine.
  • Most people get adequate niacin from diet and/or a multivitamin.

  • Food Sources : Liver, kidney, egg yolk, brewer’s yeast, broccoli, chicken, beef, whole grains, legumes
  • Adequate Intake : (mg/day)*
    Men = 5
    Women = 5
    Pregnancy = 6
    Lactation = 7
  • Upper Limit : Not determined
  • Side Effects : No adverse effects known with food or supplements
    • 6. Vitamin B6 Pyridoxine
  • Necessary for protein and fat metabolism, hormone function (estrogen and testosterone), and the production of red blood cells, niacin, and neurotransmitters (serotonin, dopamine, and norepinephrine).
  • Used therapeutically for PMS, depression, morning sickness, carpal tunnel syndrome, and heart health (lowers homocysteine, an amino acid that, at high levels, can cause arteriosclerosis and build up arterial plaque).
  • Deficiency is uncommon, except in alcoholics and the elderly, and causes seizures, irritability, depression, confusion, mouth sores, and impaired immune function.
  • Drugs that deplete vitamin B6: antibiotics, oral contraceptives, isoniazid, penicillamine, and Parkinson's drugs.
  • Supplements are recommended for the elderly, alcoholics, and those with poor diets.

  • Food Sources : Fortifi ed cereals, bananas, spinach, chicken, salmon, organ meat
  • Adequate Intake : (mg/day)
    Men and
    Women 19–50 years = 1.3
    Men 51+ = 1.7
    Women 51+ = 1.5
    Pregnancy = 1.9
    Lactation = 2.0
  • Upper Limit : (mg/day)
    Men = 100
    Women = 100
    Pregnancy = 100
    Lactation = 100
  • Side Effects : No adverse effects from food; highdose supplements may cause neuropathy (pain and numbness in extremities)
    • 7. Vitamin B12 Cobalamin
  • Required for nerve function, synthesis of DNA and RNA, metabolism of energy, enzyme reactions, and production of red blood cells.
  • Used therapeutically for heart health (lowers homocysteine), male infertility, prevention of neural tube defects, asthma, and cancer prevention.
  • Deficiency is common among the elderly and those with poor diets, pernicious anemia, depression, Alzheimer's, or malabsorption conditions (celiac disease).
  • Deficiency symptoms: anemia, appetite loss, constipation, numbness and tingling in the extremities, and confusion. Pregnant women with deficiency have increased risk of giving birth to a child with neural tube defects.
  • Drugs that deplete B12: acid-lowering drugs (omeprazole, lansoprazole, ranitidine), oral contraceptives, antibiotics, cholestyramine, and metformin.
  • Supplements are recommended for those over age 50, vegetarians, women planning to become pregnant, those with poor diets, and those at risk of heart disease.

  • Food Sources : Meat, poultry, fi sh, milk, and fortifi ed cereals
  • Adequate Intake : (mcg/day)
    Men = 2.4
    Women = 2.4
    Pregnancy = 2.6
    Lactation = 2.8
  • Upper Limit : Not determined
  • Side Effects : No adverse effects known with food or supplements
    • 8. Biotin
  • Part of the B-vitamin family; involved in the synthesis of fat, glycogen, and amino acids and enzyme reactions; required for DNA replication; important for healthy hair and nails.
  • Used therapeutically to strengthen fi ngernails.
  • Deficiency is rare except in those with hereditary disorders of biotin metabolism, liver disease, and during pregnancy (due to increased needs). It can also occur in those who consume raw egg white for prolonged periods (weeks to years) because a protein found in egg white (avidin) binds biotin and prevents its absorption or in those given intravenous feeding without biotin supplementation.
  • Deficiency symptoms include hair loss; scaly red rash around the eyes, nose, mouth, and genital area; depression; lethargy; hallucination; numbness and tingling of the extremities; and impaired glucose utilization and immune system function.
  • Drugs that deplete biotin: primidone, carbamazepine, phenobarbital, phentyoin, valproic acid, and antibiotics.
  • Most people get adequate biotin from diet and/or supplements.

  • Food Sources : Egg yolk, liver, wheat bran, yeast, oatmeal, soybeans, caulifl ower, mushrooms, and nuts
  • Adequate Intake : (mcg/day)*
    Men = 30
    Women = 30
    Pregnancy = 30
    Lactation = 35
  • Upper Limit : Not determined
  • Side Effects : No adverse effects known with food or supplements
    • 9. Folate Folic Acid
  • Part of the B-vitamin family; known as folate when it occurs in foods, or as folic acid when present in supplements or added to foods.
  • Required for cell division, growth, amino acid metabolism, enzyme reactions, and production of RNA, DNA, and red blood cells.
  • Used for heart health (lowers homocysteine) and prevention of cancer (colon and cervical) and birth defects (neural tube).
  • Deficiency occurs in alcoholics and those with poor diets, and causes anemia, fatigue, weakness, headache, hair loss, diarrhea, and poor immune function. Pregnancy or cancer results in increased rates of cell division and metabolism, increasing the need for folate.
  • Drugs that deplete folate: non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and aspirin, phenytoin, methotrexate phenobarbital, cholestyramine, colestipol, trimethoprim, and sulfasalazine.
  • Supplements are recommended for most adults for heart and cancer protection, and especially for pregnant women; multivitamins typically provide the recommended amount of 400 mcg per day.

  • Food Sources : Dark leafy vegetables, fortifi ed cereals, citrus fruits, and legumes
  • Adequate Intake : (mcg/day)
    Men = 400
    Women = 400
    Pregnancy = 600
    Lactation = 500
  • Upper Limit : Men = 1,000
    Women = 1,000
    Pregnancy = 1,000
    Lactation = 1,000
  • Side Effects : No adverse effects known from foods or supplements
    • 10. Vitamin C Ascorbic Acid
  • Required for synthesis of collagen (structural component of blood vessels, tendons, and bone), norepinephrine (neurotransmitter), and carnitine (amino acid involved in energy production); promotes wound healing; supports immune function and gum health; and has antioxidant properties.
  • Used to prevent cataracts, macular degeneration, heart disease, stroke, cancer, and colds; improve wound healing and response to stress; reduce bronchial spasms in asthmatics; and prevent lead toxicity.
  • Severe deficiency causes scurvy (bleeding, bruising, hair and tooth loss, joint pain, and swelling), which is rare today.
  • Marginal deficiencies are common among the elderly, alcoholics, and those with cancer, chronic illness, or stress. Symptoms include fatigue, easy bruising, poor wound healing and appetite, anemia, and sore joints.
  • Drugs that deplete vitamin C: oral contraceptives, aspirin, corticosteroids, and furosemide.
  • Large doses of vitamin C (greater than 1,000 mg/day) may reduce the effect of warfarin (blood-thinning drug).
  • The Linus Pauling Institute recommends 400 mg of vitamin C daily, which is higher than the RDA, yet much lower than the UL. Most multivitamin supplements provide 60 mg of vitamin C.
  • Natural and synthetic forms are chemically identical and have the same effects on the body.
  • Mineral salts of ascorbic acid (i.e., calcium ascorbate) are buffered and therefore less acidic and less likely to cause upset stomach.

  • Food Sources : Citrus fruit, tomatoes, red peppers, broccoli, strawberries, and potatoes
  • Adequate Intake : (mg/day)
    Men = 90
    Women = 76
    Pregnancy = 85
    Lactation = 120
  • Upper Limit : (mg/day)
    Men = 2,000
    Women = 2,000
    Pregnancy = 2,000
    Lactation = 2,000
  • Side Effects : Upset stomach, diarrhea, kidney stones (in those at risk), excess iron absorption