Daily Multivitamins Do Not Lower Risk of Death in Healthy Adults, Study Finds

A recent study, led by the National Institute of Health’s (NIH) National Cancer Institute, has investigated the association between taking multivitamins daily and mortality risk, finding there was not a lower risk of death among healthy adults. The research, published in JAMA Network Open, analyzed over two decades of data.

Multivitamin use is very common

In the United States, nearly one in three adults take multivitamins, with the hope of maintaining and improving health as well as preventing disease. Although multivitamin use is common, one study found only 23% of all supplements consumed were recommended by a healthcare provider.

Research into the benefits and potential risks of multivitamin supplements has produced mixed results. Observational studies are often limited by heterogeneity and confounding factors, such as the healthy user effect, where individuals who take vitamins are more likely to engage in overall healthy lifestyle behaviors. A study in 2022 analyzed data on multivitamin use and all-cause mortality from randomized clinical trials, which found insufficient evidence for determining benefits or harms. However, this may be due to limited follow-up time and lack of external validity.

Using large cohorts and longitudinal studies is therefore crucial for understanding the long-term effects of multivitamin use.

Insights from two decades of data

To this end, the new NIH study analyzed dietary data from three large and geographically diverse studies, with a sample size of over 390,000 US adults who were followed for over 20 years. Participants were deemed healthy with no history of cancer or other chronic diseases. The researchers examined the link between multivitamin use and the primary causes of chronic disease-related deaths, such as cardiovascular disease and cancer. They used repeated assessments of multivitamin use and extended follow-up periods to track mortality causes.

The analysis revealed daily multivitamin use was not associated with a decreased risk of mortality from any cause. Factors such as race, ethnicity, education and diet quality were also considered, but did not impact the results.

Multivitamin use and other health conditions

Although the researchers did not find evidence to suggest multivitamin use reduces mortality risk, they also stated in their paper that they “cannot preclude the possibility that daily multivitamin use may be associated with other health outcomes related to aging.”

Further studies may be needed to investigate multivitamin use and the risk of death in other populations, which may be impacted by nutritional deficiencies, and their effect on other health conditions.

Reference: Loftfield E, O’Connell CP, Abnet CC, et al. Multivitamin use and mortality risk in 3 prospective US cohorts. JAMA Netw Open. 2024;7(6):e2418729. doi: 10.1001/jamanetworkopen.2024.18729

This article is a rework of a press release issued by the National Institutes of Health. Material has been edited for length and content.