One in three U.S. adults takes multivitamins daily. But do they actually contribute to a longer life?

A large-scale study, encompassing data from nearly 400,000 adults, revealed that for healthy adults, daily multivitamin intake does not extend longevity. In fact, it might slightly increase the risk of mortality.

The latest study in JAMA Network Open found no mortality benefit from multivitamin supplementation; instead, during the initial follow-up years, multivitamin users faced a 4% higher mortality risk than nonusers.

The research team analyzed 390,124 U.S. adults who were part of three large-scale, geographically diverse prospective studies. The participants were generally healthy, without a history of cancer or other chronic diseases. They were followed up for more than 20 years.

"The analysis showed that people who took daily multivitamins did not have a lower risk of death from any cause than people who took no multivitamins. There were also no differences in mortality from cancer, heart disease, or cerebrovascular diseases. The results were adjusted for factors such as race and ethnicity, education, and diet quality," the news release stated.

The researchers, however, do not undermine the benefits of multivitamins for those with underlying conditions and deficiencies. For instance, beta carotene, vitamins C and E, and zinc can slow age-related macular degeneration progression. In older adults, multivitamins may improve memory and slow cognitive decline. They are also helpful in offsetting deficiencies post-bariatric surgery. Commercial products containing vitamins B12 and D provide convenient nutrient sources for many people. Additionally, folate supplementation during pregnancy prevents neural tube defects in infants.

Based on their study findings, researchers recommend that apart from these benefits, there is little health rationale for the use of multivitamin supplements.

"Micronutrients come most healthfully from food sources. When supplementation is required, it can often be limited to the micronutrients in question," the researchers wrote. "Refocusing nutrition interventions on food, rather than supplements, may provide the mortality benefits that multivitamins cannot deliver," they added.

The researchers recommend including vegetables, fruits, legumes, and cereal grains in the diet as studies have shown that they are staples in areas of remarkable longevity. Certain studies also show that the substitution of plant protein in place of animal protein may also reduce mortality.

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