Across 4 studies on vitamin D for cognitive function, 1 reported a beneficial effect, while 3 found neutral results; the predominant effect size was small. The one beneficial result was statistically significant, but the overall evidence does not support a clear cognitive benefit. No consistent dose or population emerged from the available data.
Caveats: Evidence base is small (only 4 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests.
showed limited influence on vitamin D, lipids, or kMCT effects
Ascorbic acid and a high dose of vitamin E, when given separately, also showed positive effects on cognitive performance, but there is not sufficient evidence to support their use.
Mixed results were seen for omega (ω)-3, tea, and plant extracts
Antioxidants, including vitamins C, B2, and D, along with polyphenols such as xanthohumol, fermented papaya, peanuts, and berry extracts, demonstrate the potential to support cognitive function and promote gut health through mechanisms that modulate microbiome diversity and reduce inflammation.