A recent study investigated the effects of nutrient supplementation on cognitive function. As a part of the Age-Related Eye Disease Study 2, participants at high risk of age-related macular degeneration were recruited between 2006 and 2012. The participants took part in cognitive tests in addition to their scheduled eye exams. The supplements that were assessed in the study included long-chain polyunsaturated fatty acids, lutein, zeaxanthin, vitamin C, vitamin E, beta carotene, and zinc. The researchers reported no statistical difference in cognitive functioning scores between any of the supplement groups.
Chew, EY, Clemons, TE, Agrón, E, Launer, LJ, Grodstein, F, Bernstein, PS; for the Age-Related Eye Disease Study 2 (AREDS2) Research Group “Effect of Omega-3 Fatty Acids, Lutein/Zeaxanthin, or Other Nutrient Supplementation on Cognitive Function: The AREDS2 Randomized Clinical Trial” JAMA. 2015;314(8):791-801. doi:10.1001/jama.2015.9677.