There's less peeling and chopping with pills, but even the most comprehensive vitamin pill can't provide all the benefits of a varied diet. For one thing, a multivitamin won't give you fiber, the plant material that aids digestion, prevents constipation, and helps ward off colon cancer and heart disease. Nor will it contain phytochemicals, natural compounds in plant foods that may be as essential to your good health as vitamins and minerals. Nutrition is still a relatively new science, and researchers just don't know for sure which ones, how much, and what ratios of the many different nutrients and other plant chemicals work best. In fact, they still don't even know if they've identified all of the essential nutrients. So, for the time being, it's safe to say that a multivitamin is no substitute for a healthy diet.

It's probably not a bad idea. Although diseases of malnutrition like rickets and scurvy are practically unheard of in this country today, there are some nutrients you still shouldn't skimp on. Getting 400 micrograms a day of folic acid is especially important for women who plan to have children because it can greatly lower the risk of birth defects like spina bifida, and growing evidence shows that folic acid may also cut your risk of heart disease. And if you live in the northern half of the country, you may not get enough direct sun in the winter for your body to make vitamin D. You need this nutrient to be able to absorb calcium, which is crucial for keeping your bones strong as you age. Most multivitamins contain the recommended amount of both: 400 mcg of folic acid and 400 International Units (IU) of D.

The US Institute of Medicine recently raised the Recommended Dietary Allowance (RDA) of vitamins E and C, so it's a good idea to check the multivitamin you're taking to be sure you're getting enough. The new RDA for vitamin C is 75 milligrams a day for adult women and 90 milligrams a day for adult men. If you're a smoker of either sex, you need to take an additional 35 milligrams of vitamin C to get the same benefits. The RDA for vitamin E was raised by fifty percent from previous recommendations, to a minimum of 15 milligrams a day. Some scientists feel the RDA for vitamin E should be higher still, and recommend at least 20 milligrams a day. These new recommendations reflect the latest research, including a 1996 Harvard study that found that people who took 200 IU of E a day cut their risk of heart disease nearly in half. And vitamin C has shown promise for preventing everything from cancer to cataracts; studies show you may need about seven times the recommended amount for the best results. You'd have to eat a pound of sunflower seeds and drink a half-gallon of OJ a day to get these amounts from your diet. A supplement is a more practical route; look for multivitamins that contain extra E and C or buy them as separate supplements.

No. And since most multis these days contain more than 100 percent of the recommended amounts of everything, be especially careful not to overdo it with any other supplements you may be taking. High doses of vitamin A have been linked to liver damage and birth defects. (Some health food stores carry vitamin A supplements that contain up to 25,000 IU, a dosage that can do serious harm to the liver.) Beta-carotene may raise the risk of lung cancer for smokers when taken in high potency pills. Too much zinc may hamper your body's ability to absorb copper and impair your immune system. Even too much C -- more than 1,000 mg -- can cause stomach bleeding and diarrhea. Also, you should probably avoid a supplement that contains high levels of trace minerals like manganese and molybdenum because practically everyone gets enough from food.

If you're not getting enough calcium from your diet -- dairy products as well as calcium-fortified juice and cereal are good sources -- consider taking calcium supplements. Most multivitamins don't have more than 130 mg of calcium, a small fraction of what you need for the day. Some do contain up to 450 mg, but that makes them bulky and hard to swallow, and your body can't absorb that much all at once anyway.

-- Kate Lee is a former associate editor at Consumer Health Interactive and researcher at Time Inc. Health. She is currently a senior editor at BabyCenter.

Further Resources

Roberta Larson Duyuff, MS RD CFCS, The American Dietetic Association's Complete Food &Nutrition Guide. Chronimed Publishing, 1996, 1998.

References

First published January 2, 1999
Last updated December 14, 2007
Copyright © 1999 Consumer Health Interactive and OneBody, Inc.

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