EFFECTS OF ENERGY AND MACRONUTRIENT INTAKE ON COGNITIVE FUNCTION THROUGH THE LIFESPAN

This paper reviews effects of both insufficient and excessive energy and macronutrient intake on cognition over the lifespan, including the prenatal period, infancy, childhood, and adulthood. In the brain, the hippocampus is particularly vulnerable to both protein malnutrition and energy undernutrition in utero or infancy, resulting in impaired neurogenesis and deficits in memory and spatial learning, reduced anxiety and increased impulsivity, reflected in impairments of neurotransmitter systems. Conversely, higher protein intake is associated with improved motor development but not mental development, whereas breastfeeding benefits mental development. Nevertheless, pre- and post-natal protein-energy supplementation has been shown to improve cognition in later childhood, and in adulthood, above energy alone. Similarly, n-3 essential fatty acid intake during pregnancy may have long-lasting effects on children’s cognitive abilities. However, over-nutrition, particularly during gestation, may lead to metabolic programming that increases risk of cognitive impairment. In undernourished school children, breakfasts can benefit cognitive performance. In normally nourished children, benefits of breakfast are less clear; nevertheless, acutely, breakfasts lower in glycaemic index can benefit memory, whereas higher glycaemic breakfasts may improve vigilance. This difference depends on the impact of the carbohydrate on cortisol release. In adolescents and adults, moderate carbohydrate loads can benefit cognition, provided that glucoregulation is efficient. Protein intake may benefit memory by restraining task-related cortisol release. Chronically high intake of saturated fats may contribute to cognitive decline, whereas n-3 fatty acids, and perhaps reduced energy intake, may be protective. With aging populations, dietary prediction of cognition in adults is a key area for research.