Vitamin and mineral supplements have been commonly advocated for the prevention of long term diseases in adults; especially cardiovascular diseases and cancer.
Since cancer and chronic inflammation have oxidation as their underlying mechanism and these supplements are believed to contain antioxidants that hinder these from happening.
This systematic review https://annals.org/aim/fullarticle/1767855/vitamin-mineral-supplements-primary-prevention-cardiovascular-disease-cancer-updated-systematic looked at 26 studies and concluded that the use of multivitamin supplements have no effect on the prevention of such diseases.
Summary by Dr. Nnenna A. Ukoha.
Fortmann SP, Burda BU, Senger CA, et al. Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force. Ann Intern Med. 2013;159:824–834. doi: https://doi.org/10.7326/0003-4819-159-12-201312170-00729