Making the Most Out of Multivitamins

Millions of Americans take multivitamins in the name of better health. Should you?

Medically Reviewed by David Kiefer, MD on December 26, 2010
6 min read

Millions of Americans take multivitamins in the name of better health. In spite of conflicting reports that these supplements combat chronic conditions, top health experts recommend daily multivitamins for nearly everyone.

Read on to find out why multivitamins matter, how to pick the best one, and how to bypass potential problems from the most popular dietary supplements.

A balanced diet goes a long way to getting the vitamins and minerals you need to feel good and head off health problems. Trouble is, very few people eat right every day.

“When we compare recommendations for vitamin and mineral intakes to actual consumption, many Americans do not even come close to getting what they need for several nutrients,” says Meir Stampfer, MD, DrPH, professor of medicine at Harvard Medical School.

According to the Dietary Guidelines for Americans 2005, adults are often deficient in:

“Certain groups run even higher risks for vitamin and mineral deficits,” says Jeffrey Blumberg, PhD, director of the Antioxidants Research Laboratory, and professor of nutrition at Tufts University.

Over time, small discrepancies in nutrient intakes can prove problematic for a person, particularly for women in their childbearing years, strict vegetarians, and the elderly.

For instance, shortfalls of iron in the childbearing years may lead to anemia. Too little folic acid very early in pregnancy increases the risk of neural tube defects in developing babies. And vitamin B12 deficits, responsible for irreversible nerve damage and faulty cognition, are more likely in people who avoid animal foods, and in people over age 50, whose bodies are often less efficient at absorbing vitamin B12.

Stampfer and Blumberg advocate multivitamins as a way to shore up diets low in nutrients. But, they warn that multivitamins are dietary supplements, not substitutes for healthy eating.

That’s because multivitamins lack a number of beneficial compounds for wellness, including phytonutrients, and fiber, found in plant foods. Multivitamins also typically fall short of the recommend daily amount of calcium and other important vitamins and minerals.

Think of multivitamins as an insurance policy, but don’t fool yourself into thinking dietary supplements measure up to the benefits of maintaining a healthy body weight, eating right, and getting regular physical activity, Blumberg tells WebMD.

“Overall, multivitamins are a minor component of good health, but worthy ones,” Stampfer says.

Don’t bet on multivitamins to keep you free of heart disease, cancer, and other chronic illness. That’s the recommendation of a 2006 State-of-the-Science Conference on Multivitamin/Mineral Supplements and Chronic Disease Prevention from the National Institutes of Health.

In the report, the 13-member panel concluded that more research is needed before suggesting multivitamin use to head off disease in healthy, non-pregnant people.

However, the NIH opinion contradicts earlier findings, including a 2002 study from the Harvard School of Medicine published in the Journal of the American Medical Association. The authors reviewed 35 years worth of research on vitamins and chronic disease, concluding that every adult should take a multivitamin daily as a safe and inexpensive way to optimize health.

Other studies highlight the connection between multivitamin use and well-being, too.

In a group of more than 88,000 women, those who took multivitamins for 15 years or more significantly reduced the risk of colon cancer as compared to those who took multivitamins for less time. The women were part of the Nurses’ Health Study at the Harvard School of Public Health. The research was published in the Annals of Internal Medicine.

Another study found that taking a multivitamin reduced the risk of first-time heart attack in a group of Swedish men and women aged 45 to 70.

“In bridging nutrient gaps, it is perfectly plausible to think that multivitamins help head off chronic conditions, including osteoporosis and heart disease,” Blumberg says.

So why the difference of opinion?

Stampfer, who was a presenter at the NIH conference, says the panel excluded smaller trials and observational studies done with multivitamins, looking only at the results of large randomized trials, considered the gold standard of clinical studies.

However, randomized trials tend to be shorter than other types of studies, which leaves less time to see results.

If you’re being treated for cancer, or have a history of cancer, talk with your doctor before taking a multivitamin. Dietary supplements could affect your cancer treatment.

That’s because dietary supplements could fuel the growth of cancer cells by providing the extra nutrients they need to reproduce.

And adding a multivitamin to a steady diet of other, single-nutrient supplements, highly fortified foods, or both could put you over the top for several vitamins and minerals.

If you have questions about whether a multivitamin is right for you, talk to your doctor or a dietician/nutritionist.

There may be disagreement about multivitamins’ capacity to curb chronic conditions. But on balance, the evidence for the benefits of multivitamins far outweigh the potential for harm -- considered extremely low for most healthy people -- even if the effects on health are small, says Stampfer.

If you’re convinced you need a multivitamin, how do you decide which one is best for you?

Eating a balanced diet rich in whole grains, fruits, vegetables, legumes (beans), and lean protein sources most of the time means you’d do fine with a multivitamin with 100% or less of the daily value (DV) for a wide array of nutrients. Daily values, listed on food and supplement labels, help you determine how a serving of food or supplement fits into the nutrient needs of a 2,000-calorie eating plan.

When picking a multivitamin, pay particular attention to the following to maximize benefit and minimize risk.

  • Vitamin A: Choose a supplement with beta-carotene and mixed carotenoids, the raw material your body converts to vitamin A on an as-needed basis. Excessive vitamin A as retinol (the preformed variety called acetate or palmitate on labels) is detrimental to bone and liver health.
  • Iron: Men and post-menopausal women should take an iron-free multivitamin/multimineral preparation unless their diet is very low in iron-rich foods, including meat and fortified grains. Iron may accumulate in the body and cause organ damage.
  • Folic Acid: Women in their childbearing years need 400 micrograms of folic acid (100% of the DV) every day to help prevent neural tube defects in the first month of pregnancy. (Many breakfast cereals supply 400 micrograms of folic acid per serving.)
  • Vitamin D: Most multivitamins supply 400 International Units (100% DV) for vitamin D, which is necessary for calcium absorption and may play a role in cancer prevention. Stampfer says while this is a step in the right direction, you may need more vitamin D than a multivitamin and your diet provide, especially if you have dark skin, are overweight, or spend little time outdoors in the summer months.
  • The United States Pharmacopeia (USP) Insignia: Dietary supplements, including multivitamins, are not regulated for quality or safety by the Food and Drug Administration. Still, there’s probably little cause for concern about multivitamins, since they are the most mainstream supplement. For extra assurance, seek brands with the United States Pharmacopeia (USP) symbol on the label. It guarantees safety and quality.
  • Vitamin E: Recently, some studies have shown safety concerns with “high doses” of vitamin E, or doses over 600-800 IU daily.
  • Vitamin C: The DV/RDA is low for vitamin C, so picking a multivitamin with approximately 250mg of C per day makes sense for this important and safe vitamin.