Multivitamin Supplementation for Healthy Adults

Evidence-Based Recommendations

The U.S. Preventive Services Task Force concludes with insufficient evidence to determine any balance of benefits and harms of multivitamin supplementation for preventing cardiovascular disease or cancer in healthy adults, representing an "I statement" - meaning the evidence is inadequate to make a recommendation either for or against use 1, 2, 3, 4
Multiple randomized controlled trials found no effect on all-cause mortality with multivitamin supplementation, indicating no mortality benefit 5, 6
Studies showed no effect on cardiovascular disease incidence or events, indicating no cardiovascular benefit 5, 6
Two trials showed a modest decrease in cancer incidence in men only, but not in women, limiting generalizability, indicating minimal cancer benefit 5, 6, 7

β-carotene and vitamin E should NOT be used for disease prevention in healthy adults, as β-carotene increases lung cancer risk in smokers and those with asbestos exposure, and vitamin E provides no net benefit for cardiovascular disease or cancer prevention 1, 2, 3, 4, 8
β-carotene increases lung cancer risk in smokers and those with asbestos exposure, with a Grade D recommendation to recommend against its use 1, 2, 8
Vitamin E provides no net benefit for cardiovascular disease or cancer prevention 1, 2, 8

A daily multivitamin may be appropriate for older adults, particularly those with reduced energy intake, with specific recommendations including vitamin D, calcium, and vitamin B12 supplementation 9, 10, 11
Vitamin D supplementation is recommended at 15 μg (600 IU) daily for older adults 10
Calcium supplementation is recommended at at least 1,200 mg daily from diet or supplements for older adults 10
Vitamin B12 supplementation is recommended at 4-6 μg/day for older adults due to high prevalence of deficiency 11

High-dose vitamin A can reduce bone mineral density at moderate doses and is hepatotoxic and teratogenic at high doses 1, 2
Fat-soluble vitamins (A, D, E, K) accumulate over time, and lifetime effects of high doses must be considered 1, 2
Exceeding upper intake levels of vitamins A and D can have known harms above tolerable upper limits 1, 2

For healthy adults requesting multivitamins, assess dietary intake and emphasize that supplements do not replace a healthy diet rich in fruits, vegetables, and whole grains 12
If a patient chooses to take multivitamins despite lack of evidence, there is little reason to discourage use, except for β-carotene in smokers 12
Recommend adherence to Dietary Reference Intakes and avoid doses greatly exceeding Recommended Dietary Allowance 12
Screen for specific deficiency risk factors, such as age >65, restrictive diets, malabsorption, and medications like proton pump inhibitors 11

The U.S. Preventive Services Task Force (USPSTF) concludes that evidence is insufficient to determine the balance of benefits and harms of multivitamin supplementation for cancer prevention, issuing an “I” statement (insufficient evidence)【13】.
Multiple randomized controlled trials in the general adult population found that multivitamin supplementation does not significantly affect overall cancer incidence or cancer‑specific mortality【14】【15】.

β‑Carotene supplementation significantly increases lung cancer risk in current smokers and individuals with asbestos exposure; meta‑analysis of six trials shows a pooled odds ratio of 1.24 (95 % CI 1.10‑1.39)【14】【15】【16】【17】.
The ATBC and CARET trials demonstrated higher lung cancer incidence, lung cancer mortality, and all‑cause mortality among high‑risk participants receiving β‑carotene【15】【18】【16】.
No increased cancer risk was observed in nonsmokers receiving β‑carotene【15】【16】【17】.

Vitamin E supplementation shows no overall benefit for cancer prevention and yields mixed results regarding prostate cancer risk【14】【15】.
The SELECT trial reported an increased risk of prostate cancer after extended follow‑up, whereas the ATBC study initially suggested a decreased incidence that did not persist over time【15】【18】【16】.

One randomized trial found that folic acid supplementation was associated with increased overall cancer incidence, driven primarily by excess prostate cancer deaths in the intervention arm【15】【18】【16】.