Longitudinal study of age and cohort influences on dietary patterns.

Dietary data from weighed food intake records were obtained from 35 women 29 years old and older during 4 studies from 1948 to 1966. Longitudinal data were analyzed by the use of a multiple linear-regression model with year of birth and age as independent variables. With increasing age, mean intakes declined significantly for fat, saturated fatty acids, and oleic acid, and increased significantly for calcium. After accounting for cohort effects, no significant changes occurred in mean intakes of food energy, carbohydrate, protein, phosphorus, iron, thiamin, riboflavin, preformed niacin, vitamin A, and ascorbic acid. For successive year of birth, mean intakes increased significantly for protein, calcium, phosphorus, riboflavin, preformed niacin, and linoleic acid. The regression model used explained approximately 20% of the variability in intakes of food energy and most nutrients examined.