Differences in associations of familial and nutritional factors with serum lipids between boys and girls: the Luxembourg Child Study.

BACKGROUND: Sex differences in the effects of genetic and environmental factors on circulating lipids have been examined mainly in adults, in whom the influences of sex steroid hormones are well known. OBJECTIVE: Our objective was to determine the effect of sex on genetic and environmental influences on serum lipids in prepubertal boys and girls. DESIGN: Children aged 6-8, 8-10, and 10-12 y (n = 1028) were selected at random in the Belgian province of Luxembourg, a region in Europe with a high prevalence of risk factors for cardiovascular disease and diabetes. Blood glucose and serum cholesterol, triacylglycerol, and insulin concentrations were measured, and anthropometric data and blood pressure were recorded. Familial data were obtained from standardized questionnaires. Nutritional status was obtained from a 3-d record. Participation was 70.3% of the primary cohort. RESULTS: Cholesterol, triacylglycerol, and insulin values were among the highest recorded in studies of children. In girls, cholesterol correlated positively with the energy density of intake of saturated fat (r = 0.13, P = 0.001), cholesterol (r = 0.11, P = 0.006), and protein (r = 0.12, P = 0.007) and negatively with the ratio of polyunsaturated to saturated fat intake (r = -0.14, P = 0.001) and the energy density of carbohydrate intake (r = -0.11, P = 0.019). In boys, no such relations were found. Triacylglycerol was not significantly related to nutritional factors. Consistent, independent relations were found between reported elevated cholesterol concentrations in the parental and grandparental generation and cholesterol (r = 0.101, P = 0.011) and triacylglycerol (r = 0.09, P = 0.03) in boys. No such associations were found in girls. CONCLUSION: Environmental and genetic factors may have different effects on serum cholesterol in girls and boys.