Cognitive function in old age, the long-term effects of nutraceuticals and dietary supplements, has been reviewed by D'Cunha et al. in a study published in the British Journal of Nutrition, Cambridge University Press (2018). This systematic review of the literature aggregate evidence from 25 high-quality clinical trials that stretched out over 10 years during which intervention was for at least one year in randomized, double-blinded, controlled trials with a minimum of 100 participants aged 65 years and older.

Do Nutraceuticals and Supplements Really Help with Cognitive Decline in Older Adults? A 10-Year Systematic Review

Interesting News,  Mar 29, 2025

Cognitive function in old age, the long-term effects of nutraceuticals and dietary supplements, has been reviewed by D’Cunha et al. in a study published in the British Journal of Nutrition, Cambridge University Press (2018). This systematic review of the literature aggregate evidence from 25 high-quality clinical trials that stretched out over 10 years during which intervention was for at least one year in randomized, double-blinded, controlled trials with a minimum of 100 participants aged 65 years and older.

Highlights

The study examined whether the tests on supplements, mainly B-vitamins, omega-3 fatty acids (n-3), antioxidant vitamins, and herbs, could show any positive effect on slowing cognitive decline.

  1. B-Vitamins (4 studies showed benefits):
    • Improved executive function and Mini-Mental State Examination (MMSE) scores in the subjects with elevated homocysteine levels.
    • The cognitive benefits were better when there was also a higher intake of omega-3s.
    • Cognitive decline was slightly slowed down with regards to memory recall tasks.
  2. Omega-3 Fatty Acids (1 study showed benefits):

DHA supplementation slowed down cognitive decline in persons not carrying the ApoE e4 allele.

Result: Does Science Back It?

Some benefits were found; however, the review did not have strong and consistent evidence to recommend any nutraceuticals for cognitive health in all older people. Of the 25 studies, only five showed significant cognitive improvements, and these depended on factors such as existing nutrient levels, genetics, and lifestyle.

Do Nutraceuticals Slow Cognitive Decline

Level of Evidence

This systematic review of randomized controlled trials (RCTs) offers a modest to strong level of evidence with a few limitations.

Study Design and Strength of Evidence

The review would consider:

  • 25 randomized, double-blinded, controlled trials (RCTs) → Level 1B (high-quality individual RCTs)
  • Systematic review according to PRISMA guidelines → Level 1A (strongest level of evidence)

Because systematic reviews of RCTs are among the highest levels of evidence, this study has high scientific credibility. However, significant cognitive benefits were apparent in only 5 out of 25 studies, implying that overall evidence for nutraceuticals against cognitive decline is still not very sound.

Final Evidence-Based Assessment

  1. Strength: High because of systematic review of RCTs
  2. Limitation: Limited positive results; benefits depended on baseline nutrient levels, genetics, and lifestyle
  3. More Research Needed In: Future long-term studies with larger sample sizes examining interactions with diet, exercise, and biomarkers.

What Next?

These studies must see how supplements operate along with diet, exercise, blood, genetics, and other biomarkers to better understand their roles in brain health. For now, however, a balanced diet, an active lifestyle, and maintaining key nutrients at the right level naturally remain the best approach to cognitive aging.