Nutrition in adolescence. A longitudinal study in dietary patterns from teenager to adult.

This thesis reports the longitudinal changes in dietary intake of a group of Dutch adolescents, 103 girls and 97 boys from about 12 to 21 years of age (part of 'The Amsterdam Growth and Health Study'). The subjects were pupils of a secondary school, and measured five times. A dietary history method was used to assess the food intake. Special reference was made of differences between schooldays and weekend days. In girls the observed total energy intake was almost constant over the whole age range (9.5 mJ), whereas in boys the nutrient intake gradually increased with age from about 11 mJ/day at age 12, to 14 mJ/day at age 21. On weekend days the energy intake of girls and boys in all age-groups was consistently higher. Compared to the recommendations of the Netherlands Nutrition Council, the food intake of these teenagers contained too much saturated fat, and not enough poly-saccharides. In general, the mineral and vitamin intake was comparable to the recommendations. Only in girls the intake of iron was borderline. In both sexes some overconsumption of energy was likely, because during the period of study an increased percentage of body fat was found. Snacks supplied about 20-25 % of the total daily energy intake in both sexes (on weekend days about 30 %). The alcohol consumption increased strongly with age, from 1 g/day at age 13 in both sexes, to 7 g/day in girls and 18 g/day in boys at the young adult age. The teenage food pattern was compared with a Dutch meal-planning- disk. It is indicated that the nutrient definitions, given in this model, are too general. The food consumption was divided in a relatively high and low quality diet. Girls with a relatively high quality diet showed lower body fat mass and better physical performance (e.g. higher aerobic power). In boys no relationship could be demonstrated. Early maturing (skeletal age) girls and boys consumed less energy, but also showed a lower habitual physical activity and were fatter than late maturers.It is concluded that the dietary pattern of these observed youngsters was not different from the Dutch population in general