What to take for cognition

Graded by the strength of the evidence — strongest first. Nothing here is sold to you.

Caffeinegrade Areliably improves alertness, reaction time, and vigilance
Creatinegrade BMeta-analysis of 16 RCTs (n≈492 adults): improved memory, attention, and processing speed; no significant effect on overall or executive function.
Lion's Manegrade Cearly, small studies suggest a modest cognitive effect
Ginkgograde Cno reliable benefit for preventing cognitive decline in large trials
L-Theaninegrade Cimproves attention and reduces distraction, especially combined with caffeine
Irongrade Cimproves attention/cognition when iron deficiency is present; no benefit if replete
Ashwagandhagrade Cpreliminary improvements in memory/executive function; small trials
Omega-3not well studiednot adequately studied for cognition in healthy adults