The effect of postprandial glycaemia on cognitive function: a randomised crossover trial

Area of Science:

• Nutrition Science
• Cognitive Neuroscience
• Human Metabolism

Background:

• Inconsistent findings exist regarding the impact of postprandial (after meal) blood glucose levels on cognitive function.
• Methodological limitations in previous studies necessitate robust research designs to clarify the relationship between glycemia and cognition.

Purpose of the Study:

• To investigate the acute effects of postprandial glycemia, manipulated by carbohydrate digestion rate, on cognitive performance in young adults.
• To determine if consuming foods with differing glycemic index (GI) values influences cognitive test scores.

Main Methods:

• A double-blind, randomized, crossover trial involving 65 young adult participants.
• Participants consumed trifle sweetened with either a high-GI sucrose (GI 65) or a low-GI isomaltulose (GI 34).
• Cognitive tests assessing memory and processing speed were administered at baseline, 60 minutes, and 120 minutes post-consumption.

Main Results:

• No significant differences in memory recall (free word recall, short/long delay recall, letter-number sequence, visuo-spatial recall) were observed between the high-GI and low-GI conditions at 60 or 120 minutes.
• Participants demonstrated significantly faster performance on Reitan's trail-making test B at 60 minutes after consuming the higher-GI trifle compared to the lower-GI trifle (P = 0.037).

Conclusions:

• The study suggests that acute differences in postprandial glycemia induced by varying carbohydrate digestion rates do not significantly impair memory function in healthy young adults.
• While memory appears unaffected, higher GI carbohydrate consumption may transiently enhance certain aspects of cognitive processing speed, as indicated by the trail-making test results.