As a nutrition support pharmacist, Patients will ask you if multivitamins are beneficial due to reports in the lay press that they don't help. Multivitamins do NOT reduce the risk of heart disease, cancer, or death in HEALTHY adults. And too much can be harmful. High-dose beta-carotene may increase the risk of lung cancer in smokers and too much vitamin E may increase the risk of hemorrhagic stroke, prostate cancer, and mortality.
Advise adults that they don't need a multivitamin as long as they're healthy and get their essential nutrients from food. Watch for people who could benefit from SPECIFIC nutrients that they can get in a multivitamin or separate supplement.
Children should get vitamin D if they don't get enough from formula or milk. Recommend 400 to 800 IU/day with the higher dose for kids at risk for deficiency or living at higher latitudes. For further information see our note, "Vitamin D supplementation in infants and children". Adults often need vitamin D especially if they have limited sun exposure or live at northern latitudes. Recommend 800 to 2000 IU/day. For further information see our notes, "Vitamin D deficiency in adults" and "Clinical points on vitamin D supplements in adults".
Women of childbearing age should get folic acid 400 mcg/day from fortified foods and/or supplements to decrease the risk of neural tube defects during early pregnancy. For further information see our notes, "Help pregnant choose the right prenatal vitamin" and "Nutrition during pregnancy". Older adults may need calcium if they don't get enough in their diet. Recommend a total of 1200 mg/day from diet and supplements. For further information see our note, "Using calcium supplements safely".
Some drugs or conditions may contribute to nutrient deficiencies. For example, long-term PPIs or metformin can lower vitamin B12 levels and bariatric surgery can reduce absorption of many nutrients. For further information see our notes, "Treatment of METFORMIN-induced vitamin B12 deficiency".
REFERENCES
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Moyer VA; U.S. Preventive Services Task Force. Vitamin, mineral, and multivitamin supplements for the primary prevention of cardiovascular disease and cancer: U.S. Preventive services Task Force recommendation statement. Ann Intern Med. 2014 Apr 15;160(8):558-64. Available at: https://pubmed.ncbi.nlm.nih.gov/24566474
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 US Preventive Services Task Force. 2013. In: Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK169368
NHS Choices (2019). Do I need vitamin supplements? [online] NHS. Available at: https://www.nhs.uk/common-health-questions/food-and-diet/do-i-need-vitamin-supplements
Johns Hopkins Medicine Health Library. (2019). Is There Really Any Benefit to Multivitamins? [online] Available at: https://www.hopkinsmedicine.org/health/wellness-and-prevention/is-there-really-any-benefit-to-multivitamins