How to Pick a Vitamin Supplement
By Nancy Brinch, MS, RD, LSW
Nearly every adult can benefit from taking a multivitamin and mineral supplement.
According to researchers at Harvard University many Americans don't get enough
vitamins from food alone. So if you currently don't take a daily multivitamin and mineral
supplement, you might want to start.
How to Select a Supplement
Many supplements seem to have no rationale behind the amounts of vitamins and
minerals included. Some have far more than you need. Even if the high levels are not
dangerous, they are a waste of money. Some supplements include an imbalance of
vitamins and minerals. Here's what to look for in a supplement:
•About 100 - 150% of the Daily Value for the following vitamins: thiamin, riboflavin,
niacin, B-6, B-12, folic acid, A, C, D, and E.
•Doses of vitamin A (retinol, which is also called vitamin A palmitate or acetate) should
be no greater than 4000 IU (in one study higher doses increased the risk of hip fracture in
women.). Levels of beta carotene (which can be converted to vitamin A as needed by the
body) should not exceed 15,000 IU (higher doses may increase the risk of lung cancer in
•Vitamin B-6 should not be higher than 100 milligrams (higher doses may cause
reversible nerve damage.)
•Vitamin E should be in the natural form (d-alpha tocopherol) because this is absorbed
better than the synthetic form (d,l-alpha tocopherol). The recommended dose of vitamin
E is 33 IU. Recent research on high doses of vitamin E (800 IU) has shown no beneficial
effects and some possible disadvantages (women with heart disease who took 800 IU of
vitamin E daily for 3 years were more likely to die than those who took a placebo). Doses
of 200 - 400 IU daily are safe.
•The National Academy of Science's (NAS) recommended levels for vitamin C are 90
mg. for men and 75 mg. for women. Many experts recommend 200 mg. daily.
Supplements containing 60 mg. of vitamin C are sufficient if food sources of vitamin C
are included in the diet (i.e. orange juice, citrus fruits, strawberries, cantaloupe, tomatoes,
broccoli, green and red peppers.) NAS recommends no more than 2000 mg. of vitamin C
•About 100% for the following minerals: chromium, zinc, copper, and selenium. Taking
too much of one mineral can interfere with another mineral (i.e. taking too much zinc can
interfere with the absorption of copper.)
•Iron amounts should be 18 milligrams for premenopausal women and no more than 9
milligrams for adult males and postmenopausal women.
•Calcium and magnesium at the recommended amounts are too bulky to fit in a single
multivitamin and mineral supplement. Supplemental calcium and magnesium can be
taken in a separate supplement. Calcium intake from food and supplements should total
1000 milligrams a day (do not exceed 2500 milligrams). Magnesium intake from both
food and supplements should total 320 milligrams daily for women and 420 milligrams
for men. Getting more than 350 milligrams from a supplement can cause diarrhea. (Good
food sources of magnesium are whole grain breads and cereals, nuts, beans, and leafy
•The letters "USP" should appear on the label. This stands for United States
Pharmacopeia. This designation means the supplement meets established standards for
disintegration, dissolution, potency, purity, and expiration date.
•Most generic brands are equivalent to their brand name counterparts. Major supermarket
and pharmacy chains as well as major discount retailers sell supplements that are
identical to brand name counterparts. You can save money by purchasing these "knock-
Multivitamins and minerals should be taken with a meal or snack. If you take a fiber
supplement, leave several hours between taking the fiber supplement and the
multivitamin and mineral supplement. Fiber can trap minerals making them unavailable
to the body.
Remember that taking vitamin and mineral supplements will not give you a competitive
edge. Vitamins and minerals do not provide energy to the body. They also do not contain
fiber and the beneficial phytonutrients found in plant foods. However, supplements do
provide nutritional insurance with almost no risk as long as these guidelines are followed.