What supplements are safe and potentially beneficial for overall and cognitive health in a generally healthy 75‑year‑old man, with minimal or rare side effects?

Recommended Supplements for a 75-Year-Old Male

For a 75-year-old man, I recommend vitamin D supplementation (if deficient) at >800 IU daily and omega-3 fatty acids (EPA+DHA) at approximately 1-2 grams daily, with consideration of a daily multivitamin containing B vitamins and antioxidants—these have the strongest evidence for cognitive and overall health benefits with minimal side effects.

Vitamin D: Screen First, Then Supplement

Vitamin D stands out as the most evidence-based recommendation for this age group. Older adults should be screened for vitamin D deficiency (serum 25OHD <30 ng/mL or 75 nmol/L), which affects nearly 50% of people over 65 1.

Key Evidence:

• Hypovitaminosis D increases risk of cognitive decline and dementia in older adults 1
• Longitudinal studies establish that low vitamin D precedes cognitive decline (not the reverse) 1
• Supplementation >800 IU daily showed a fivefold reduction in Alzheimer's risk after 7 years 1
• Cognitive benefits appear within 4 weeks and are strongest for executive function and processing speed 1
• Target: Raise serum 25OHD above 30 ng/mL (75 nmol/L)—supraphysiological doses are unnecessary 1

Important caveat: While vitamin D should not be used as a diagnostic biomarker for Alzheimer's disease due to lack of specificity 1, correcting deficiency is recommended for this population regardless of cognitive status.

Omega-3 Fatty Acids (EPA+DHA): Strong Cardiovascular and Cognitive Support

Combined EPA and DHA supplementation shows cognitive benefits, particularly in those with coronary artery disease or lower baseline omega-3 levels 2.

Dosing and Effects:

• Effective dose: 1320 mg EPA + 880 mg DHA daily (approximately 2.2 grams total omega-3s) 2
• Cognitive aging was delayed by at least 30 months in those achieving an omega-3 index ≥4% 2
• Benefits maintained at 30 months, with improvements in executive function 2
• Those with omega-3 index <4% showed no cognitive change 2

Clinical pearl: The evidence suggests starting before significant cognitive decline occurs, as benefits are strongest in early or mild impairment rather than established Alzheimer's disease 2.

Multivitamins: Emerging Evidence for Memory

Recent high-quality evidence supports daily multivitamin use specifically for memory preservation 3, 4.

The COSMOS-Web Trial:

• Daily multivitamin (Centrum Silver) improved memory performance equivalent to 3.1 years of age-related memory change 3
• Benefits appeared at 1 year and persisted through 3 years 3
• Effect was specific to episodic memory (immediate recall); no effect on executive function 3
• Safe and accessible intervention 3

Nuance: The evidence is strongest for memory domains, with mixed results for global cognition 4, 5. Benefits appear most pronounced in those with baseline nutritional deficiencies or mild cognitive impairment 4.

B Vitamins: Limited Evidence Despite Biological Plausibility

While B vitamins (B6, B12, folic acid) have theoretical benefits, the evidence shows they probably have little or no effect on global cognitive function at any time point up to 10 years 6.

• Multiple studies with 27,882 participants showed SMD values from -0.03 to 0.06 (essentially no effect) 6
• This applies to cognitively healthy adults in their 60s-70s 6

Exception: B vitamins may still be appropriate if there is documented deficiency, but not specifically for cognitive enhancement in well-nourished individuals.

Antioxidant Vitamins: Mixed Long-Term Results

Evidence for vitamins C, E, and β-carotene is inconsistent 6.

• β-carotene showed benefit only after 18 years of treatment (MD 0.18 TICS points) 6
• Vitamin C showed benefit after 5-10 years (MD 0.46 TICS points) 6
• Critical safety concern: Vitamin E supplementation increased prostate cancer diagnoses in one large trial 6

Given the very long duration needed for benefit and safety concerns, these are not first-line recommendations.

What NOT to Recommend

Zinc, copper, and selenium: Moderate to low-certainty evidence shows no meaningful cognitive effects 6. Selenium showed no effect on dementia incidence (HR 0.83) 6.

Calcium with low-dose vitamin D3 (400 IU): No effect on cognitive function or dementia incidence over 10 years 6. The dose was likely too low.

Practical Implementation Algorithm

1. Check vitamin D level (25OHD)

   • If <30 ng/mL: Supplement with 800-2000 IU daily
   • Recheck in 3 months, adjust to maintain >30 ng/mL

2. Start omega-3 fatty acids

   • Dose: 1-2 grams EPA+DHA daily (combined)
   • Choose pharmaceutical-grade fish oil to minimize contaminants
   • Consider higher end of range if history of cardiovascular disease

3. Add daily multivitamin

   • Standard formulation (e.g., Centrum Silver)
   • Primarily for memory support
   • Avoid megadoses of individual vitamins

4. Monitor for side effects

   • Omega-3s: GI upset, fishy aftertaste (take with meals)
   • Vitamin D: Rare at recommended doses; avoid if hypercalcemia
   • Multivitamins: Generally well-tolerated

Critical Timing Consideration

Start supplementation before cognitive decline or with only mild impairment—the evidence consistently shows that interventions are most effective when initiated early 2, 4, 5. Once Alzheimer's disease is established, benefits are minimal to absent 2.

Safety Profile

All three recommended supplements (vitamin D at appropriate doses, omega-3s, and standard multivitamins) have excellent safety profiles with minimal or rare side effects in older adults 3, 6. This makes them appropriate for long-term use in this population.