Sensory control of energy density at different life stages.

Taste preferences, food choices and eating habits all change with age. The transition from childhood to adolescence and adult life is associated with reduced sweet taste preferences, lower sugars consumption and reduced energy density of the diet. Ageing is associated with elevated acceptance of bitter tastes, elevated preferences for vegetables and salad greens, and increased consumption of whole grains, vegetables and fruit. The age-associated drop in energy intakes is achieved through a reduction in the weight and volume of food consumed, as well as a reduction in the overall energy density of the diet. Energy density drops from a peak of 5 kJ (1.2 kcal)/g in adolescence and early adult life to a low of 3.1 kJ (0.75 kcal)/g for adult women aged 45-54 years. Older adults, particularly women, consume less fat and saturated fat and more fibre and vitamin C, suggesting a shift in consumption from snacks, sweets and desserts towards grains, vegetables and fruit. These changes in food preferences and eating habits are associated, on a population level, with a decline in preferences for sweet taste and with increased acceptance of bitter tastes. At present there are no data to show a causal relationship between age-related changes in sensory function and the selection of a more bulky energy-dilute diet. However, it is a plausible hypothesis that sensory factors mediate adjustments in energy density of foods at different life stages.