Postprandial effects of breakfast glycaemic index on cognitive performance among young, healthy adults: A crossover clinical trial

Objective: To evaluate the postprandial effects of high and low glycaemic index (GI) breakfasts on cognitive performance in young, healthy adults. Methods: A crossover clinical trial including 40 young, healthy adults (aged 20-40 years, 50% females) recruited from primary healthcare centres in Salamanca, Spain. Verbal memory, phonological fluency, attention, and executive functions were examined 0, 60, and 120 minutes after consuming a low GI (LGI), high GI (HGI), or water breakfast. Every subject tried each breakfast variant, in a randomized order, separated by a washout period of 7 days, for a total of 3 weeks. Results: A significant interaction between the type of breakfast consumed and immediate verbal memory was identified (P<.05). We observed a trend towards better performance in verbal memory (delayed and immediate), attention, and phonological fluency following an LGI breakfast. Discussion: Cognitive performance during the postprandial phase in young, healthy adults was minimally affected by the GI of breakfast. The potential for breakfast's GI modulation to improve short- and long-term cognitive functioning requires further research.