The ABCs of Vitamins
By Andrea Sercu

Let this glossary serve as a guide to your daily nutrient requirements. 

In a perfect world you'd eat plenty of leafy green and orange vegetables for vitamins A, C and beta-carotene, dairy products for calcium and legumes and/or meat for iron. But if you're like most people, you probably don't always get your fill of the necessary nutrients and need vitamin supplements to help supply the missing links.

Antioxidants Nutrients such as beta-carotene, vitamins C and E and selenium help the body fight cancer by blocking certain chemical reactions of toxins. You can find a good mix of antioxidants in multivitamins, but check to make sure yours contains at least 25,000 IU beta-carotene, along with other carotenes, including alpha-carotene, lutein, zeaxanthin and lycopene.

Beta-carotene A derivative of vitamin A, beta-carotene is a member of the carotenoid family, vitamins found in such fruits and vegetables as yams, cantaloupe, leafy green vegetables, squash, peaches and mangoes. Of the carotenoids, beta-carotene, in particular, has received much acclaim in past years after numerous studies indicated a reduction in cancer and heart disease in those people who ingested large amounts of yellow-orange fruits and vegetables and leafy greens.

Vitamin C Hailed for its immune-strengthening properties, this mainstay vitamin has also been linked to stronger blood vessels and connective tissue, dense bones, reduced heart attack risk and relief from asthma.
Vitamin C is found naturally in citrus fruits and some vegetables, but if you're taking it in supplement form it's best absorbed as a soluble powder rather than a tablet. Most experts recommend that you need about 1,000 to 2,000 milligrams two to three times a day.

Vitamin E Because this vitamin is fat soluble, it should be consumed with food for maximum absorption. Most people under age 40 require a daily intake of 400 IU; people over age 40 need about 800 IU. Look for natural forms, noted on ingredient listings as d-alpha-tocopherol, as opposed to the synthetic form, dl-alpha-tocopherol. It's a good idea to take vitamin E with selenium, which together enhance each other's absorption capacity.

Selenium This trace mineral has been gaining increased popularity for its antioxidant properties. The average daily recommended dosage for selenium is about 200 to 300 micrograms. While you should take selenium with vitamin E, vitamin C can inhibit the action of some selenium forms, so you may want to take these two antioxidants at different times in the day.

Vitamin B-12 This vitamin-known as the energy enhancer of the vitamin alphabet-works by boosting the bone marrow's production of red blood cells. It's helpful in fighting heart disease and even memory loss. Some women report a heightened energy benefit during menstruation. Many people get their daily requirement from meat, milk and eggs, but vegetarians, and particularly vegans-those vegetarians who also don't eat any milk products-run the risk of having low B-12 levels. Older people, who can't absorb this vitamin from food sources as easily as younger people, are also at risk.

Folic Acid Folic acid is particularly helpful to pregnant women in fighting birth defects and those prone to heart disease. The synthetic form of the B vitamin folate, folic acid helps the body control high levels of homocysteine, an amino acid linked to arterial disease. After observing a study of 5,056 men in the 1970s, Ottawa epidemiologist Dr. Howard Morrison found those with low folate levels were almost 70 percent more likely to die from heart problems in the years following the study.
In pregnant women, folate stops neural tube defects, most notably spina bifida. Folic acid is critical to the development of a baby's brain and spine, especially in the first 28 days of conception, so pregnant women need to take folic acid as early in the gestation cycle as possible.

Some medical experts recommend taking 400 micrograms, but if you have a history of convulsive disorders or hormone-related cancer, it's best not to exceed 400 micrograms a day.
And if you're a vegetarian or an older adult, know that folic acid can disguise the signs of a vitamin B-12 deficiency. Nevertheless, if you're like 90 percent of Americans who aren't getting enough folic acid from such foods as dark green leafy vegetables, carrots, orange juice or wheat germ, a supplement containing this important nutrient is probably in order.

VITAMINS U.S. RDA FUNCTION
Vitamin A 5,000 IU -- Maintains healthy skin, bones, hair, eyes and teeth
Beta Carotene 25,000 IU -- Converts to vitamin A as needed; reduces cancer, heart disease risk
Vitamin B-1 1.5 mg -- Helps convert energy from food; maintains nervous system (Thiamine)
Vitamin B-2 1.7mg -- Helps convert energy from food; maintains skin, eyes (Riboflavin)
Vitamin B-3 20 mg -- Helps convert energy from food; maintains skin, nervous system and mental functions (Niacin)
Vitamin B-6 2 mg -- Helps convert energy from food; helps body metabolize protein and fat; helps body synthesize red blood cells, hemoglobin
Vitamin B-12 6 mcg -- Provides energy; prevents anemia
Vitamin C 60 mg -- An antioxidant that helps maintain bones, teeth, collagen; aids iron absorption, red blood cells; strengthens blood vessels and connective tissue
Vitamin D 400 IU -- Helps the body absorb and metabolize calcium, phosphorus for strong teeth and bones
Vitamin E 30 IU -- An antioxidant that helps guard cell membranes, fats and vitamin A from oxidation; protects red blood cells
Folic Acid 400 mcg -- Helps red blood cell production; spurs metabolism of fats, amino acids, DNA and RNA; aids cells division; prevents birth defects; lowers heart disease and cancer risk