A recent study identified the effects of a glycemic index, or the measure of carbohydrate quality, and glycemic load, or the measure of carbohydrate quality and quantity, on mood and cognitive function in adolescents. After random assignment of different types of breakfasts to 74 adolescent schoolchildren, it was clear that low-glycemic index and high-glycemic load breakfast resulted in better mood and cognitive ability. “On balance, it would appear that the low-GI high-GL breakfast may help to improve learning.”
Breakfast is an important meal of the day, but what the exact effect of the macronutritional composition of breakfast on cognitive function in schoolchildren was unknown. Glucose being the major energy source used by the central nervous system, this study investigated breakfast meals that differed in their blood glucose-raising potential. Glycemic index (GI) and glycaemic load (GL) are two important parameters to evaluate the blood glucose-raising potential of the breakfast meal. Glycemic index is indicative of the carbohydrate absorption rate, while glycemic load indicates the quantity of carbohydrate absorbed. Authors considered both parameters to evaluate the quality of breakfast conducive for learning. They also examined blood glucose and cortisol levels (stress indicator) to explore the underlying mechanisms for the effects of breakfast on mood and cognitive function in adolescents.
* Researchers selected 74 children (girls and boys), aged 11 to 14 years in good health from five different schools in London.
* After initial screening, children were randomly assigned to high- or low-glycemic load group. Within each group, children got high- and low-glycemic index breakfast. They were asked to eat and drink only water 10 to 12 hours before testing.
* High-glycemic foods included white bread, low-nutrient cereals, full-fat diary, soda; low-glycemic foods included oats, whole grains, fruit.
* Blood-glucose and saliva-cortisol levels were measured before breakfast (baseline), 90 minutes after the start of breakfast and after cognitive function tests.
* Statistical analysis was done to find differences in mood, cognitive function, glucose and cortisol levels between the breakfasts.
* Blood glucose levels shot up to higher levels initially in those who consumed high-glycemic index meals, whereas in those who had high-glycemic load meals, blood glucose was high even after 2.5 hours of breakfast.
* Higher cortisol levels were found after eating high-glycemic index meals.
* A low-glycemic index high-glycemic load breakfast improved mood approximately 90 to 140 minutes after breakfast.
* A low-GI meal helped children perform better on verbal memory tasks and a high-glycemic index meal helped them on vigilance-requiring tasks.
This study investigated 74 children from five schools in London. More children should be included from other schools to incorporate a more varied mix of the population. Although glucose is a very important component of the meal, a follow-up study should be done on other macronutrients such as proteins and lipids to provide a complete picture of a healthy breakfast that enhances learning abilities in children. Also, providing all four test meals instead of two to each child could help clarify the results better.
The daytime meal after an overnight fast plays an important role in influencing our memory and learning. There is a need to do more research on the nutritional value of the breakfast meal. The key findings of this study suggest the benefits of a low-glycaemic index high-glycaemic load breakfast. The children felt fuller and less thirsty, and hence more careful and energetic after eating low-glycaemic index and high-glycaemic load breakfast. These meals elevate mood and cognitive function. School breakfast policies could consider this low-glycaemic index high-glycaemic load meal composition for breakfast to enhance the learning and academic potential of their students.
For More Information:
Glycaemic Index and Glycaemic Load of Breakfast Predict Cognitive Function and Mood in Schoolchildren: A Randomised Controlled Trial
Publication Journal: British Journal of Nutrition, 2011
By Renata Micha; Peter J. Rogers; King’s College London, England and University of Bristol, England
*FYI Living Lab Reports Are Summaries of the Original Research.