In spite of a recent study suggesting that taking a daily multivitamin may do more harm than good, HSPH researchers say that may not be the case, especially for people who don’t eat a healthful diet. A daily multivitamin pill offers a safe and simple dose of essential micronutrients. Nearly 40 percent of adults in the U.S. take a multivitamin to ensure good health. (1) A recent study in Iowa women suggests that this daily habit may be doing more harm than good. (2) A closer look, however, reveals major flaws in the study—and offers reassurance that taking a daily multivitamin may still be a smart move.
The precise requirements for various vitamins have been controversial since their discovery in the late 1800s and early 1900s. The early recommendations were based on the amounts needed to avoid so-called diseases of deficiency such as scurvy (too little vitamin C), beri-beri (too little vitamin B1), pellagra (too little vitamin B3), and rickets (too little vitamin D). Ongoing research suggests a broader role for vitamins. Work by Dr. Bruce N. Ames of the University of California, Berkeley, and others shows that deficiencies in many micronutrients can lead to damage to DNA, the essential “blueprint” of each cell. (3) Such damage can cause or accelerate aging-related conditions. (4) This would make chronic conditions such as cancer, heart disease, vision loss, and a host of others a new type of deficiency disease.
For those who eat a healthy diet, a multivitamin may have little or no benefit. A diet that includes plenty of fruits, vegetables, whole grains, good protein packages, and healthy fats should provide most of the nutrients needed for good health. But not everyone manages to eat a healthful diet. When it comes to micronutrients, many Americans get less than the adequate amounts, according to criteria set by the Institute of Medicine. For example, more than 90 percent of Americans get less than the Estimated Average Requirement for vitamin D and vitamin E from food sources alone. (5) Many older people have trouble absorbing vitamin B12 from food; the Dietary Guidelines for Americans 2010, in fact, recommends that people over the age of 50 eat foods fortified with vitamin B12 or take vitamin B12 supplements.
Getting enough of another B vitamin, folate, is especially important for women who may become pregnant, since adequate folate can help lower the risk of having a baby with spina bifida or anencephaly. For the folate to be effective, it must be taken in the first few weeks of conception, often before a woman knows she is pregnant. Yet in the U.S., half of all pregnancies are unplanned. That’s why the Centers for Disease Control and Prevention recommends that all women of childbearing age (ages 15 to 45) consume 400 micrograms per day of folic acid. (7) And a standard multivitamin that contains the Recommended Dietary Allowance (RDA) for folic acid offers a convenient way to do that.
For these reasons, we believe a daily multivitamin-multimineral pill offers safe, simple micronutrient insurance, and the findings from the latest study don’t change our recommendation.