Can Multivitamins Prevent Heart Disease and Cognitive Decline? New Research Examines Evidence

Taking a daily multivitamin may improve vitamin levels in the body, but its ability to prevent major diseases or improve long-term health remains uncertain, according to a new review. Researchers found that while multivitamins consistently improved certain nutrient levels, their effects on memory, heart health, pregnancy outcomes, and other health conditions varied considerably.

Published in the Journal of Dietary Supplements, the review examined clinical evidence on the effectiveness and safety of multivitamin supplementation across different adult populations.

Researchers searched scientific databases through September 9, 2026, and identified 157 eligible publications, including 103 primary intervention reports and 54 related studies.

The review focused on oral multivitamin formulations containing a broad range of vitamins and minerals, evaluating their effects on nutritional status, cognitive function, cardiovascular health, pregnancy outcomes, and overall wellbeing.

The findings revealed that multivitamin supplementation consistently increased blood levels of vitamin B6, vitamin B12 and folate.

However, improvements in minerals such as iron, zinc and iodine varied depending on participants' nutritional status, health conditions and supplement formulations.

Some clinical trials reported improvements in memory and cognitive performance among older adults. However, other studies found no significant cognitive benefits, and evidence that multivitamins prevent dementia remains insufficient.

Pregnancy-related studies also reported selected benefits, including reductions in low birth weight and premature births, although findings differed across populations.

Importantly, large clinical trials did not establish consistent cardiovascular benefits from routine multivitamin supplementation.

Researchers found that multivitamins were generally well tolerated, although some participants experienced digestive discomfort, rashes or bleeding-related adverse events.

The review also highlighted potential interactions between vitamin K-containing supplements and blood-thinning medications.

However, researchers did not formally assess study bias or conduct a meta-analysis, limiting the certainty of their conclusions.

The findings suggest that multivitamins may be particularly useful for individuals with nutritional deficiencies or increased dietary needs.

REFERENCE: Fan, Z., Nelson, J. M., & Wallace, T. C. (2026). Multivitamins – A Scoping Review of Clinical Trials Examining Their Efficacy and Safety. Journal of Dietary Supplements, 1–48. DOI: 10.1080/19390211.2025.2597204