Improved cognitive performance following supplementation with a mixed-grain diet in high school students: a randomized controlled trial.

Objective: Adolescence is a stage of rapid growth, when rich nutritional supplementation is important. Maintaining optimal cognitive functioning is critical in high school students, who are under considerable academic pressure. The objectives of this study were to identify the effects of a 9-wk randomly assigned diet of mixed grains versus a regular diet on cognitive performance and on levels of plasma brain-derived neurotrophic factor (BDNF) and S100B, a calcium-binding protein produced by astroglial cells, in healthy high school students (grades 10 and 11).

Methods: In this 9-wk, single-blind, controlled study, subjects were randomly allocated to either a mixed-grain or a regular diet. Cognitive assessments and measurements of plasma BDNF and S100B levels were performed at baseline and after the 9-wk intake of a mixed-grain or regular diet. Computerized neuropsychological tests and self-rating scales were used for the cognitive assessments.

Results: Significant improvements in some neuropsychological tests were found after 9 wk in both the mixed-grain and the regular-diet groups, but the changes from baseline between the two groups were not significantly different. Significant impairments on the AX-continuous performance test were observed at the endpoint in the regular-diet group, and the changes from baseline between the two groups were also significantly different for this test. A significant difference in changes in BDNF levels was observed between the two groups.

Conclusions: These results suggest that intake of mixed grains for 9 wk is beneficial for cognitive performance and plasma BDNF levels in high school students. These beneficial effects seem to be related to the prevention of cognitive deterioration in a mental-fatigue test with the mixed-grain diet, rather than cognitive enhancement per se.