French children start their school day with a hydration deficit.

摘要

Fluid requirements of children vary as a function of gender and age. There is believed to be very little literature on the hydration status of French children. This study assessed the morning hydration status in a large sample of 529 French schoolchildren aged 9-11 yr. Recruited children completed a questionnaire on fluid and food intake at breakfast, and collected a urine sample the very same day after breakfast. Breakfast food and fluid nutritional composition were analysed and urine osmolality was measured using a cryoscopic osmometer. More than a third of the children had a urine osmolality of 801-1000 mosm/kg, while 22.7% had a urine osmolality >1000 mosm/kg. This was more frequent in boys than in girls (p < 0.001). A majority of children (73.5%) drank <400 ml at breakfast. Total water intake at breakfast was significantly and inversely correlated with high osmolality values. It is concluded that almost two thirds of the children in this large cohort had evidence of a hydration deficit when they went to school in the morning, despite breakfast intake, and that children's fluid intake at breakfast does not suffice to maintain an adequate hydration status for the whole morning.