Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life.

Systematic review and meta-analysis of randomized trials in cognitively healthy adults aged 40 years or older, mostly community-dwelling older adults in their 60s and 70s. Some included trials enrolled people with cardiovascular risk factors, mild vitamin B12 deficiency, or other comorbidities, and several studies were limited to one sex.

The review evaluated vitamin and mineral supplementation for preserving cognition in cognitively healthy adults aged 40 years and older. Included regimens were heterogeneous, ranging from vitamin E 600 mg daily for 3 months to B-vitamin combinations such as folic acid 2.5 mg/day, vitamin B6 50 mg/day, and vitamin B12 1 mg/day, with some trials also testing folate/B-vitamin regimens combined with omega-3 fatty acids.

Overall, vitamin and mineral supplementation did not improve global cognitive function or clearly prevent dementia in cognitively healthy midlife and older adults. The evidence does not support recommending supplementation to maintain cognition. In the largest reported B-vitamin comparison, cognitive impairment occurred in 50/908 versus 49/895 participants (RR 1.01, 95% CI 0.69 to 1.48; moderate-certainty). Some long-term antioxidant trials suggested small possible benefits on select cognitive outcomes, but the findings were inconsistent and uncertain.

The evidence base was clinically and methodologically heterogeneous, with different vitamins, minerals, combinations, doses, durations, and cognitive outcomes. Several trials were small or open-label, and the overall certainty was low to moderate with inconsistent effects across time points and domains, limiting confidence and generalizability.