Determinants of blood pressure in childhood and adolescence.

Relationships between blood pressure and dietary factors were investigated in 434 boys and 450 girls aged 9 years. Dietary data were obtained from a food-frequency questionnaire which was completed by parents. This was used to estimate daily energy intake and the intake of 14 nutrients considered likely to influence blood pressure. Blood pressure was tested for relationships to absolute and calorie-adjusted intakes of each nutrient after adjustment for age, weight, height, socio-economic status and the month of examination. Ambient temperature was the most important determinant of blood pressure, an increase of 10 degrees C being associated with a 6-7 mmHg fall in blood pressure. Diastolic blood pressure in boys was negatively related to energy intake and to calorie-adjusted fibre intake. Mean adjusted diastolic blood pressure in boys in the top fibre intake quartile was 2.5 mmHg lower than that in the lowest quartile. Systolic blood pressure in girls was negatively related to calorie-adjusted intakes of protein. There were no relationships between blood pressure and calorie-adjusted intakes of fats, carbohydrates, sodium, potassium, calcium or magnesium.