Effects on cognitive performance of modulating the postprandial blood glucose profile at breakfast

Abstract

Background/objectives: Considering the importance of glucose as a brain substrate, the postprandial rate of glucose delivery to the blood could be expected to affect cognitive functions. The purpose was to evaluate to what extent the rate of glucose absorption affected measures of cognitive performance in the postprandial period. In addition, cognitive performance was evaluated in relation to individual glucoregulation.

Subjects/methods: A white wheat bread (WWB) enriched with guar gum (G-WWB) with the capacity to produce a low but sustained blood glucose net increment was developed. The G-WWB was evaluated in the postprandial period after breakfast with respect to effects on cognitive function (working memory and selective attention (SA)) in 40 healthy adults (49-71 years, body mass index 20-29 kg/m(2)), using a high glycaemic index WWB for comparison in a randomised crossover design.

Results: The G-WWB improved outcome in the cognitive tests (SA test) in the later postprandial period (75-225 min) in comparison with the WWB (P<0.01). Subjects with better glucoregulation performed superior in cognitive tests compared with subjects with worse glucoregulation (P<0.05).

Conclusions: Beneficial effects on cognitive performance were observed with the G-WWB in the late postprandial period. The positive effect is suggested to emanate from improved insulin sensitivity, possibly in a combination with an enhanced neural energy supply. The results highlight the importance of carbohydrate foods that induces a low but sustained blood glucose profile in enhancing postprandial cognitive functions.