Do Multivitamins Work?

Do Multivitamins Work?

The medical community is still debating the possible benefits.

When vitamins were first studied a century ago, it seemed like a wonderful solution for nutritional deficiencies. Scurvy, rickets and other diseases that arose from a lack of certain vitamins (in these cases, vitamins C and D, respectively) could now be more easily prevented. This eventually gave rise to the idea of a daily multivitamin that could fill in nutritional gaps and maybe even provide additional health benefits, like preventing heart disease and cancer. But, now with improvements to the modern diet, recent research doesn’t quite back up the need for a multivitamin.

Research says: no clear benefit

Although results have been mixed, a series of studies that included a review of research from the United States Preventative Services Task Force found no clear benefit in taking vitamins for all-cause mortality, cardiovascular disease, cognitive health or cancer.

The current edition of Dietary Guidelines for Americans stresses that nutritional needs should be met primarily from foods. Eating healthful whole foods, like vegetables, fruits, whole grains, nuts and fish, can usually provide all of the necessary nutrients, without the use of a multivitamin. Plus, eating whole foods gives you a total package of nutrients, containing fiber and other natural substances that help your body absorb what it needs.

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Interestingly, the National Institutes of Health’s (NIH) Office of Dietary Supplements, notes that people who take multivitamins tend to consume more vitamins and minerals from food than those who don’t — probably because, to begin with, they’re more concerned about their health.

Can they do harm?

Even if there’s no benefit, taking one can’t hurt, right? In most cases, that’s probably true for multivitamins, according to the NIH. The only damage may be to your wallet — and your money is better spent on whole foods. But, megadoses — especially of fat-soluble vitamins, like A, K and E, that don’t get flushed out in urine — could harm your health, so avoid individual supplements, unless your doctor approves them.

Some people may benefit.

There may be some exceptions to the no-vitamin rule, though: Women of childbearing age (even those who aren’t planning on becoming pregnant) should take 400 micrograms of folic acid daily, to help prevent neural tube defects, which develop in the earliest stages of pregnancy. Postmenopausal women may benefit from a calcium supplement to protect their bones.

Those on special diets, like vegetarians or vegans, may also benefit from a multivitamin. In addition, many people, especially those who spend most of their time indoors, may have a vitamin D deficiency. Talk to your doctor, though, before you start taking a vitamin D supplement, as you may need to be tested for the deficiency first.

“Since we do not have strong evidence supporting the use of multivitamins, and they may in fact be harmful, I like to work closely with my patients to ensure that their diets are providing optimum nutrition,” says Jennifer Boozer, DO, family medicine physician at Keck Medicine of USC and clinical assistant professor of family medicine (clinician educator) at the Keck School of Medicine of USC. “In certain cases we do need to supplement individual vitamins or minerals that may be missing. An annual preventative exam is a great opportunity to discuss this.”

The bottom line? Most healthy people who eat a balanced diet probably don’t need a multivitamin. Before taking any supplement, even a multivitamin, talk to your doctor, especially if you are on other medications or have any health conditions. Too much of some vitamins may interact with your medications or cause your condition to worsen. Your doctor can discuss your specific situation to see if there’s any benefit — or harm — for you in taking a multivitamin.

by Tina Donvito

Make an appointment with one of our physicians at Keck Medicine, to discuss your multivitamin use. If you’re in the Los Angeles area, schedule an appointment, by calling (800) USC-CARE (800-872-2273) or by visiting