Are multivitamins (dietary supplements) beneficial for generally healthy adults with a balanced diet?

Are Multivitamins Worth It for Healthy Adults?

For generally healthy adults with a balanced diet, multivitamins are not worth taking—there is insufficient evidence they prevent cardiovascular disease or cancer, and they provide no mortality benefit. 1, 2, 3

The Evidence Against Routine Multivitamin Use

The U.S. Preventive Services Task Force has consistently concluded that current evidence is insufficient to assess any balance of benefits and harms of multivitamins for preventing cardiovascular disease or cancer in healthy adults. 1, 2, 3 This represents an "I statement"—meaning the evidence is inadequate to make a recommendation either for or against use. 2

Key findings from randomized controlled trials:

• No mortality benefit: Multiple trials found no effect on all-cause mortality with multivitamin supplementation. 2
• No cardiovascular benefit: Studies showed no effect on cardiovascular disease incidence or events. 2
• Minimal cancer benefit: Two trials showed a modest decrease in cancer incidence in men only, but not in women, severely limiting generalizability. 2

This lack of benefit is echoed by major medical organizations. The American Heart Association recommends that healthy persons receive adequate nutrients by eating a variety of foods rather than supplementation. 1 The American Cancer Society found that current evidence does not support the use of dietary supplements for the prevention of cancer. 1

Specific Vitamins You Should Actively Avoid

β-carotene and vitamin E should NOT be used for disease prevention in healthy adults. 2, 3 This is a Grade D recommendation—meaning you should actively recommend against their use. 1

• β-carotene increases lung cancer risk in smokers and those with asbestos exposure. 1, 2
• Vitamin E provides no net benefit for cardiovascular disease or cancer prevention. 1, 2

When Multivitamins May Be Appropriate

While not beneficial for the general population, certain groups may benefit from supplementation:

Older adults (age >65) with reduced energy intake should be considered for daily multivitamin supplementation. 2, 4 This population is at significant risk of two or more micronutrient deficiencies, with clear associations between multiple deficiencies and frailty. 4

Specific recommendations for older adults:

• Vitamin D: 15 μg (600 IU) daily 2, 4
• Calcium: At least 1,200 mg daily from diet or supplements 2, 4
• Vitamin B12: 4-6 μg/day due to high prevalence of deficiency 2, 4

Important Safety Concerns and Pitfalls

Fat-soluble vitamins (A, D, E, K) accumulate over time, and lifetime effects of high doses must be considered. 2 High-dose vitamin A can reduce bone mineral density at moderate doses and is hepatotoxic and teratogenic at high doses. 2

Exceeding upper intake levels of vitamins A and D can have known harms above tolerable upper limits. 2

Clinical Approach for Patients Requesting Multivitamins

When a patient asks about multivitamins, follow this algorithm:

1. Assess dietary intake: Determine if they consume adequate fruits, vegetables, and whole grains. 2

2. Screen for specific deficiency risk factors: 2

   • Age >65 years
   • Restrictive diets (vegan, elimination diets)
   • Malabsorption conditions
   • Medications like proton pump inhibitors

3. Emphasize food first: Supplements do not replace a healthy diet rich in fruits, vegetables, and whole grains. 2

4. If they choose to take multivitamins despite lack of evidence: There is little reason to discourage use, except for β-carotene in smokers. 2 However, recommend adherence to Dietary Reference Intakes and avoid doses greatly exceeding Recommended Dietary Allowance. 2

The Bottom Line

The Academy of Nutrition and Dietetics noted that although multivitamin supplements may be useful in meeting the recommended levels of some nutrients, there is no evidence that they are effective in preventing chronic disease. 1 For healthy adults with balanced diets, the money spent on multivitamins would be better invested in purchasing nutrient-rich whole foods.