"Alpha-glycerylphosphorylcholine (Alpha GPC) supplementation has been shown to increase choline availability in the brain and improve markers of cognitive function and mental performance, particularly under conditions of fatigue and physical exertion."
Bellar, D., LeBlanc, N.R. & Campbell, B. (2015). The effect of 6 days of alpha glycerylphosphorylcholine on isometric strength. Journal of the International Society of Sports Nutrition, 12, 42.
"L-Tyrosine supplementation has been shown to improve cognitive performance, working memory, and stress resilience in subjects exposed to demanding mental and environmental conditions."
Jongkees, B.J., Hommel, B., Kühn, S. & Colzato, L.S. (2015). Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands. Journal of Psychiatric Research, 70, 50 to 57.
"L-Theanine, a non-protein amino acid found naturally in tea, has been shown to promote relaxation without sedation, improve attention, and reduce stress-related markers in healthy adults."
Williams, J.L., Everett, J.M., D'Cunha, N.M., Sergi, D., Georgousopoulou, E.N., Keegan, R.J., McKune, A.J., Mellor, D.D., Anstice, N. & Naumovski, N. (2020). The effects of green tea amino acid L-theanine consumption on the ability to manage stress and anxiety levels: a systematic review. Plant Foods for Human Nutrition, 75(1), 12 to 23.