This study was designed to determine the differences between young and elderly people on the perceived intensity and pleasantness of sucrose in foods, in relation to their food intake. First, a group of 35 young subjects (mean age: 22 +/- 2 years) and 29 elderly subjects (mean age: 79 +/- 6 years) judged the intensity and the pleasantness of 5 series of breakfast items: orange lemonade, strawberry jam, strawberry yoghurt, chocolate paste, and grain porridge, each with 5 geometrically spaced sucrose concentration levels. On average, the elderly people had a lower slope of the sucrose psychophysical function. Optimal preferred sucrose concentrations were higher for the elderly compared to the young. The second phase in the study concerned the effects of the different optimal sucrose concentrations in foods on food intake. The second experiment dealt with 2 different optimal preferred sucrose concentrations (elderly vs. young subjects) in the food items: orange lemonade, strawberry and blueberry jam, and strawberry and blueberry yoghurt, served during breakfast. A group of 33 young people (mean age: 23 +/- 2 years) and 25 elderly subjects (mean age: 82 +/- 5 years) participated in a crossover study of 2 5-day (breakfast) treatments. Subjects are ad lib from these foods and other items such as bread, coffee, and tea. The results showed that the sucrose concentration had no effect on the absolute amount consumed, although total energy intake of the breakfast increased with the higher sucrose foods. No clear difference was found in pleasantness between the 2 breakfasts with the different sucrose concentrations. These findings indicate that a flavor concentration evaluated as being most pleasant by the elderly with the help of small amounts of stimuli (in a lab setting) does not necessarily predict the pleasantness and the food intake behaviour in realistic settings.