Multivitamin Supplementation for Healthy Adults
For healthy adults without nutritional deficiencies, multivitamins provide no proven benefit for preventing cardiovascular disease, cancer, or reducing mortality, and routine supplementation is not recommended. 1
Evidence-Based Recommendations
General Adult Population
The U.S. Preventive Services Task Force (USPSTF) concludes with insufficient evidence to determine any balance of benefits and harms of multivitamin supplementation for preventing cardiovascular disease or cancer in healthy adults. 1 This represents an "I statement" - meaning the evidence is inadequate to make a recommendation either for or against use.
- No mortality benefit: Multiple randomized controlled trials found no effect on all-cause mortality with multivitamin supplementation. 1
- No cardiovascular benefit: Studies showed no effect on cardiovascular disease incidence or events. 1
- Minimal cancer benefit: Two trials (Physicians' Health Study II and SU.VI.MAX) showed a modest decrease in cancer incidence in men only (pooled relative risk 0.93), but not in women, limiting generalizability. 1
Specific Vitamins to Avoid
β-carotene and vitamin E should NOT be used for disease prevention in healthy adults. 1
- β-carotene increases lung cancer risk in smokers and those with asbestos exposure (Grade D recommendation - recommend against). 1
- Vitamin E provides no net benefit for cardiovascular disease or cancer prevention. 1
Populations That May Benefit from Supplementation
Older Adults (≥65 years)
A daily multivitamin may be appropriate for older adults, particularly those with reduced energy intake (<1500 kcal/day). 1, 2, 3
Specific recommendations for elderly:
- Vitamin D: 15 μg (600 IU) daily supplementation recommended year-round. 2
- Calcium: At least 1,200 mg daily from diet or supplements, ideally four portions of calcium-rich dairy foods. 2
- Vitamin B12: 4-6 μg/day recommended due to high prevalence (12-15%) of deficiency from atrophic gastritis and medication use. 3
- Protein: Not a vitamin, but critical - 1-1.2 g/kg body weight daily to maintain muscle mass. 2
Excluded Populations (Not Covered by These Recommendations)
These guidelines do NOT apply to: 1
- Pregnant or potentially pregnant women (who require folic acid supplementation)
- Children
- Chronically ill or hospitalized patients
- Individuals with known nutritional deficiencies
Important Caveats and Pitfalls
Potential Harms
- High-dose vitamin A: Can reduce bone mineral density at moderate doses; hepatotoxic and teratogenic at high doses. 1
- Fat-soluble vitamins (A, D, E, K): Accumulate over time; lifetime effects of high doses must be considered. 1
- Exceeding upper intake levels: Vitamins A and D have known harms above tolerable upper limits. 1
Quality Control Issues
Commercial multivitamin formulations vary considerably in content and concentration, making it difficult to extrapolate clinical trial results to over-the-counter products. 1
Cost Considerations
Despite lack of proven benefit, Americans spent $28.1 billion on dietary supplements in 2010, representing substantial healthcare expenditure without demonstrated return. 1
Clinical Approach
For healthy adults requesting multivitamins:
- Assess dietary intake - emphasize that supplements do not replace a healthy diet rich in fruits, vegetables, and whole grains. 1
- If patient chooses to take multivitamins despite lack of evidence, there is little reason to discourage use (except β-carotene in smokers). 1
- Recommend adherence to Dietary Reference Intakes; avoid doses greatly exceeding Recommended Dietary Allowance. 1
- Screen for specific deficiency risk factors (age >65, restrictive diets, malabsorption, medications like proton pump inhibitors). 3, 4
Bottom line: Multivitamins are generally safe but provide no proven benefit for disease prevention in healthy adults. 5, 6, 7, 8 Focus instead on evidence-based preventive measures: smoking cessation, blood pressure control, lipid management, diabetes screening, cancer screening, obesity counseling, and appropriate aspirin use. 1