According to the National Institutes of Health (NIH), it's estimated that one-third of all U.S. adults start their day with a multivitamin supplement. It's easy enough to pick up one of the many options from the grocery store or pharmacy—and the idea that we're fueling our bodies to fight off infections and stay in shape makes the investment worth it. However, a new study casts some doubt on the effectiveness of these popular supplements. Do multivitamins help with longevity, or are they doing more harm than good?
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The study—led by researchers at the NIH National Cancer Institute (NCI) and published in JAMA Network Open on June 26—followed nearly 400,000 U.S. adults for over 20 years, finding no association between regular multivitamin use and a lower risk of death. In fact, it was the opposite: During the first few years of follow-up, multivitamin use was associated with a 4 percent higher risk of all-cause mortality.
According to a press release outlining study findings, NCI researchers wanted to "more deeply explore the relationship between long-term regular multivitamin use and overall mortality and death from cardiovascular disease and cancer." Previous studies have looked at multivitamins and mortality, but there have been mixed results, and those studies were also limited by shorter follow-up periods.
In the current study, researchers examined data from three large studies in which all participants were "generally healthy, with no history of cancer or other chronic diseases." When compared with those who didn't take multivitamins, vitamin-takers didn't have any lower risk of death.
Specifically, researchers found no difference in risk of death from cancer, heart disease, or cerebrovascular diseases. (The release indicates that these results were adjusted for factors like race and ethnicity, education, and diet quality.)
Overall, evidence suggests that "there is little health rationale for the use of multivitamin supplements," study experts wrote in an accompanying editorial comment. They concede that there is sometimes a need for supplementation, but that "can often be limited to the micronutrients in question."
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Studies show that supplements can sometimes have adverse effects as well, including "iron overload" in the event people consume too much iron from a supplement on top of food, and reduced antibiotic absorption from calcium and zinc supplements.
With that in mind, researchers posit that long-term health and longevity might be better accomplished by maintaining a healthy diet.
"Refocusing nutrition interventions on food, rather than supplements, may provide the mortality benefits that multivitamins cannot deliver," the editorial comment reads. "Vegetables, fruits, legumes, and cereal grains are staples in areas of remarkable longevity, known as Blue Zones—Okinawa, Japan; Sardinia, Italy; the Nicoya Peninsula, Costa Rica; the island of Ikaria, Greece; and Loma Linda, California."
The Nurses' Health Study and Health Professionals Follow-up Study illustrated this by finding that eating more vegetables and fruits was associated with reduced mortality, as was substituting plant proteins for animal proteins. The optimal amount was five servings of either fruits or veggies daily.
Even better, researchers note that healthy foods deliver these micronutrients while simultaneously providing macronutrients and fiber. These dietary swaps also limit your consumption of saturated fat and cholesterol.
