Across 3 studies, 1 observational study found a small beneficial association between selenium levels and cognitive function in elderly adults, while 2 systematic reviews reported neutral findings. The predominant effect direction is neutral with small effect sizes. Evidence is preliminary and limited by small sample sizes and lack of interventional data.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. The only significant finding came from an observational study, which cannot establish causation. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. Study durations were not consistently reported, limiting assessment of optimal exposure length.
showed limited influence on vitamin D, lipids, or kMCT effects
Blood Se levels were positive associations with cognitive scores (β=0.049, 95% CI: 0.022, 0.076) and all four cognitive domains.
Mixed results were seen for omega (ω)-3, tea, and plant extracts