Forbes et al. carried out a systematic study on 24 randomized controlled trials published in Can Geriatr J. (2015) that examined whether nutrients, dietary supplements, and vitamins could improve cognitive functioning in middle-aged and older adults without dementia. All our trials were required to last at least three months and evaluated the effects of omega-3 fatty acids, B vitamins, vitamin E, or other nutritional interventions.

Do Nutrients and Supplements Improve Cognitive Function? A Systematic Review and Meta-Analysis

Interesting News,  Mar 31, 2025

Forbes et al. carried out a systematic study on 24 randomized controlled trials published in Can Geriatr J. (2015) that examined whether nutrients, dietary supplements, and vitamins could improve cognitive functioning in middle-aged and older adults without dementia. All our trials were required to last at least three months and evaluated the effects of omega-3 fatty acids, B vitamins, vitamin E, or other nutritional interventions.

Key Findings

  • No effects of omega-3 fatty acids were evidenced on cognitive performance, namely about Mini- Mental-State-Examination (MMSE) scores and memory tasks.
  • No significant improvement was found in cognitive performance due to B vitamins in a non-demented population.
  • No measurable benefit was derived from vitamin E supplementation on cognitive outcomes.

Some other nutritional interventions, such as green tea extract, Concord grape juice, chromium picolinate, beta-carotene, and combinations of multivitamins, demonstrated some promising effects on cognition in isolated studies, and further research is needed.

Level of Evidence: "Do Nutrients and Supplements Improve Cognitive Function? A Systematic Review and Meta-Analysis"

This systematic review and meta-analysis of randomized controlled trials offer moderate to strong evidence in the hierarchy of evidence-based medicine.

Study Design & Strength of Evidence

The review included:

  • 24 randomized controlled trials (RCTs) → Level 1B (high-quality individual RCTs)
  • Meta-analysis of RCTs → Level 1A (greatest level of evidence)
Do Nutrients and Supplements Improve Cognitive Function A Systematic Review and Meta-Analysis – What Science Says_FRL

Since systematic review and meta-analysis of RCTs are counted amongst the highest levels of evidence, this study has great credibility. Nevertheless, findings suggested no effect of omega-3s, B vitamins, or vitamin E on cognitive functioning, which indicate that while there is strong evidence, the efficacy of these supplements remains unsupported.

Final Evidence-Based Assessment High

Strength: Due to systematic review and pooled meta-analysis of randomized controlled trials

Limitation: No significant benefits found for most nutrients; other individual studies showed potential for various interventions, but need to be researched further

Future Research Needed: Longer-term trials investigating specific populations, lifestyle factors, and biomarker interactions

Final Verdict: Does Science Support It?

The review found that there was no solid evidence for improvement of cognitive function by omega-3, B vitamins, and vitamin E in healthy middle-aged and older adults. Some other dietary compounds showed their potentials, but more studies are needed before endorsing them to prevent cognitive decline or dementia. Presently, the well-balanced diet, regular physical ability, and good lifestyle is the best condition for cognitive health, leaving further research into the nutrient-lifestyle factor-genetics-biomarker interactions for understanding better the long-term effects on brain health.