Vitamins & Minerals

Vitamins and minerals are substances your body needs in small but steady amounts for normal growth, function and health. Together, vitamins and minerals are called micronutrients. Your body can't make most micronutrients, so you must get them from the foods you eat or, in some cases, from supplements. Many people don't receive all of the nutrients they need from their diet because they either can't or don't eat enough, or they can't or don't eat a variety of healthy foods. For some people, including those on restrictive diets, multivitamin-mineral supplements can provide vitamins and minerals that their diets often don't. Pregnant women and older adults have altered nutrient needs and may also benefit from a supplement.

Vitamins

Vitamins are needed for a variety of biologic processes, among them growth, digestion, mental alertness and resistance to infection. They also enable your body to use carbohydrates, fats and proteins, and they act as catalysts — initiating or speeding up chemical reactions. Though vitamins are involved in converting food into energy, they supply no calories.

Vitamins can be either water-soluble or fat-soluble.

Water-soluble vitamins. Vitamin C, biotin and the seven B vitamins — thiamin (B₁), riboflavin (B₂), niacin (B₃), pantothenic acid, pyridoxine (B₆), folic acid, and cobalamin (B₁₂) — dissolve in water (water-soluble) and aren't stored in your body in any significant amounts. Surplus water-soluble vitamins are simply excreted in your urine.

Fat-soluble vitamins. Any extra vitamin A, D, E or K not used by your body right after ingestion is stored in your body fat and liver. Excess fat-soluble vitamins can accumulate in your body and become toxic. You're especially sensitive to excess amounts of vitamins A and D. Because vitamins E and K affect blood clotting, talk with your doctor before taking a supplement that contains either of these vitamins if you're taking a blood thinner, such as warfarin (Coumadin).

Vitamin	Best Sources	Functions	Deficiency Symptoms
A (Carotene 5000 IU)	Liver, eggs, yellow & green fruits and vegetables, milk & dairy products, fish liver oil	Growth & repair of body tissues [resist infections], bone & tooth formation, night vision	Night blindness, dry, scaly skin, loss of smell & appetite, tooth decay, fatigue, susceptibility to infection
B₁ (Thiamin - 1.5 mg)	Wheat germ, yeast, liver, whole grains, nuts, fish, poultry, dried beans, meats	Carbohydrate metabolism, appetite maintenance, nerve function, growth & muscle tone	Beriberi, heart irregularity, nerve disorders, fatigue, loss of appetite, forgetfulness
B₂ (Riboflavin - 1.7 mg)	Whole grains, green leafy vegetables, organ meats	Fat, carbohydrate, & protein metabolism, cell respiration, antibody & red blood cell formation	Eye problems, cracks in corners of mouth, digestive disturbances
B₆ (Pyridoxine 2.0 mg)	Fish, poultry, lean meats	Fat, carbohydrate, & protein metabolism, antibody formation, nerve function	Nervousness, dermatitis, blood disorders, muscular weakness, insulin sensitivity, anemia
B₁₂ (Cobalamin - 6 mcg)	Organ meats, eggs, milk, fish, cheese	Fat, carbohydrate, & protein metabolism, maintains nerve function, blood cell formation	Pernicious anemia, nervousness, neuritis, fatigue, brain degeneration
Biotin (300 mcg)	Yeast, organ meats, legumes, eggs	Fat, carbohydrate, & protein metabolism, fatty acid formation, helps utilize B vitamins	Dry, grayish skin, depression, muscle pain, fatigue, poor appetite
Choline (No RDA)	Organ meats, fish, soybeans, wheat germ, egg yolk	Nerve transmission, fat & cholesterol metabolism, regulates liver & gall bladder	High blood pressure, bleeding stomach ulcers, liver & kidney problems
Folic Acid (Folacin - 400 mcg)	Green leafy vegetables, organ meats, dairy products	Red blood cell formation, protein metabolism, growth & cell division	Anemia, gastrointestinal problems, poor growth
Niacin (20 mg)	Meat, poultry, fish, milk products, peanuts, brewer's yeast	Fat, carbohydrate, & protein metabolism, health of skin, tongue, & digestive system, blood circulation	Fatigue, indigestion, irritability, loss of appetite, skin disorders
Pantothenic Acid (10 mg)	Lean meats, whole grains, legumes	Converts nutrients into energy, formation of some fats, vitamin utilization	Vomiting, stomach stress, restlessness, infections, muscle cramps
C (Ascorbic Acid - 60 mg)	Citrus fruits, vegetables, tomatoes, potatoes	Wound healing, blood vessel strength, collagen maintenance, resistance to infection	Scurvy, bleeding gums, slow healing wounds, bruising, aching joints, nosebleeds, poor digestion
D (400 IU)	Fish-liver oils, egg yolk, organ meats, fish, fortified milk, sunlight	Bone formation, heart action, nervous system maintenance	Rickets, poor bone growth, nervous system irritability
E (30 IU)	Vegetable oils, green vegetables, wheat germ, organ meats, eggs	Cellular respiration, protects fat soluble vitamins & red blood cells, inhibits blood coagulation	Muscular wasting, abnormal fat deposits in muscles, gastrointestinal disease, heart disease
K (No RDA)	Green leafy vegetables, dairy products, fruits, green tea	Formation of blood clotting agents	Tendency to hemorrhage

Minerals

Minerals are the main components in your teeth and bones, and they serve as building blocks for other cells and enzymes. Minerals also help regulate the balance of fluids in your body and control the movement of nerve impulses. Some minerals also help deliver oxygen to cells and help carry away carbon dioxide.

Minerals have two categories:

Major minerals. Calcium, phosphorus, magnesium, sodium, potassium, sulfur and chloride are considered major minerals because adults need them in larger amounts — more than 250 milligrams (mg) a day.

Trace minerals: Chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium and zinc are considered trace minerals because your body needs them in smaller amounts — fewer than 20 mg a day.

Mineral	Best Sources	Functions	Deficiency Symptoms
Calcium (1200 mg)	Milk & milk products, dark green leafy vegetables, fortified foods	Strong bones, teeth, muscle tissue, regulates heart beat, muscle action & nerve functions, blood clotting	Soft, brittle bones, back & leg pain, heart palpitations, tetany
Chromium (No RDA)	Corn oil, clams, whole grain cereals, brewer's yeast	Glucose metabolism [energy], increases effectiveness of insulin	Atherosclerosis, glucose intolerance in diabetes
Copper (2 mg)	Oysters, nuts, organ meats, legumes	Formation of red blood cells, bone growth & health, works with vitamin C to form elastin	General weakness, impaired respiration, skin sores
Iodine (150 mcg)	Seafood, iodized salt	Component of hormone thyroxine which controls metabolism	Goiter, dry skin & hair, nervousness, obesity
Iron (18 mg)	Meats & organ meats, fish, leafy green vegetables, poultry	Hemoglobin formation, improves blood quality, increases resistance to stress & disease	Anemia [pale skin, fatigue], constipation, breathing difficulties
Magnesium (40 mg)	Nuts, seeds, green vegetables, whole grains	Acid/alkaline balance, metabolism of carbohydrates & minerals	Nervousness, tremors, easily aroused anger, disorientation, blood clots
Manganese (No RDA)	Nuts, whole grains, fruits, vegetables	Enzyme activation, fat & carbohydrate production, sex hormone production, skeletal development	Dizziness, poor muscle coordination, ear noises
Phosphorus (1000 mg)	Fish, meat, poultry, eggs, whole grains	Bone development, important in fat, protein, & carbohydrate utilization	Poor bones & teeth, arthritis, rickets, appetite loss, irregular breathing
Potassium (No RDA)	Lean meats, vegetables, fruits	Fluid balance, control activity of heart muscle, nervous system, kidneys	Poor reflexes, irregular heartbeat, dry skin, general weakness
Selenium (50 - 200 mcg)	Seafood, organ meats, lean meats, whole grains, Brazil nuts, eggs	Protects body tissues against oxidation damage from radiation, pollution & normal metabolic processing	Heart muscle abnormalities
Zinc (15 mg)	Lean meats, liver, eggs, seafood, whole grains	Involved in digestion & metabolism, important in development of reproductive systems, aids in healing	Retarded growth, prolonged wound healing, loss of appetite

Supplements

Supplements, as the term suggests, can complement your regular diet, but they aren't food substitutes. They can't replace the hundreds of nutrients found in whole foods. But if you do decide to take a vitamin or mineral supplement, consider these factors:

Check the supplement label. Read labels carefully. Product labels can tell you what the active ingredient or ingredients are, which nutrients are included, the serving size — for example, capsule, packet or teaspoonful — and the amount of nutrients in each serving. The label also provides directions for safe use and tips for storage along with the name and address of the manufacturer, packer or distributor where you can write if you need more information on a particular product.

Avoid supplements that provide "megadoses." In general, choose a multivitamin-mineral supplement — for example, Centrum, One A Day, others — that provides about 100 Percent Daily Value (%DV) of all the vitamins and minerals instead of one that supplies, for example, 500%DV of one vitamin and only 20%DV of another. The exception to this is calcium. You may notice that calcium-containing supplements don't provide 100%DV. If they did, the tablets would be too large to swallow. Most cases of nutrient toxicity stem from high-dose supplements.

Look for “USP” on the label. This ensures that the supplement meets the standards for strength, purity, disintegration and dissolution established by the testing organization, U.S. Pharmacopeia (USP).

Beware of gimmicks. Synthetic vitamins are usually the same as so-called "natural" vitamins, but "natural" vitamins usually cost more. And don't give in to the temptation of added herbs, enzymes or amino acids — they add mostly cost.

Look for expiration dates. Supplements can lose potency over time, especially in hot and humid climates. If a supplement doesn't have an expiration date, don't buy it. If your supplements have expired, discard them.

Store all vitamin and mineral supplements safely. Store supplements in a dry, cool place. Avoid hot, humid storage locations, such as the bathroom. Also, store supplements out of sight and away from children. Put supplements in a locked cabinet or other secure location. Don't leave them on the counter or rely on child-resistant packaging. Be especially careful with any supplements containing iron. Iron overdose is a leading cause of poisoning deaths among children.

Play it safe. Before taking anything other than a standard multivitamin-mineral supplement of 100%DV or less, check with your doctor, pharmacist or a registered dietitian. High doses of some vitamins or minerals may cause health problems. For example, high doses of vitamin B-3 (niacin) can result in or worsen liver problems, and too much vitamin A over time may cause liver problems or weaken bones in women. In addition, supplements may interfere with your medications. For instance, vitamin E isn't recommended if you're taking blood-thinning medications (anticoagulants) because it can complicate the proper control of blood thinning. If you're already taking an individual vitamin or mineral supplement and haven't told your doctor, discuss it at your next checkup.

This information was brought to you by the Institute of Medicine of the National Academies.

For a printable copy of the recommended intakes of vitamins & minerals, click here . This is a pdf file. Download to view this file.

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