The brain and carbohydrates

SWANSEA, UNITED KINGDOM. The human brain requires glucose and oxygen in order to function. During rest the brain accounts for 20% of the body's energy consumption even though it comprises only 2% of total body weight. Recent studies using position emission tomography (PET scan) has shown that increased mental activity is associated with increased glucose metabolism and that the glucose goes directly to the areas of the brain involved in the mental activity at hand. Researchers at the University of Wales provide a review of the effect of carbohydrates on memory and mood. Among the highlights of their findings:

Memory processing by the hippocampus may be limited by glucose availability.
A plentiful glucose supply improves memory possibly because glucose increases the synthesis of the neurotransmitter acetylcholine.
Low glycemic index foods improve memory more than high glycemic index foods.
Missing breakfast results in poorer memory performance during the morning.
A low carbohydrate diet is associated with increased depression, anger and tension over the long term. People with better glucose tolerancehave better mood and memory. Better glucose tolerance is associated with a rapid fall in blood glucose levels after ingestion of a glucose drink.

The researchers conclude that the nature and timing of meals and snacks can influence psychological functioning and that the glycemic load of the diet has adirect impact on mood and memory.
Benton, David and Nabb, Samantha. Carbohydrate, memory, and mood. Nutrition Reviews, Vol. 61, May 2003, pp. S61-S67