High intake of milk, but not meat, decreases bone turnover in prepubertal boys after 7 days

OBJECTIVE: To compare the short-term effect of a high milk and a high meat intake, identical in protein amount, on bone turnover during prepuberty. SETTING: A University department. DESIGN AND SUBJECTS: From 28, randomly recruited, 8-year-old boys, first 14 were assigned to the milk group and next 14 to the meat group. In each group, 12 boys finished the dietary intervention. INTERVENTION: Milk (1.5 l/day) and meat (250 g/d), both containing approximately 53 g of protein, were given together with the habitual diet for 7 days. At baseline and day-7, serum osteocalcin (s-OC), bone-specific alkaline phosphatase (s-BAP) and C-terminal telopeptides of type I collagen (s-CTX) were measured (immunoassay) and dietary intake was estimated (a 3-day weighted food record). RESULTS: Baseline s-OC, s-BAP and s-CTX were not significantly different between the groups. After 7 days, the average protein intake increased in both groups by 47.5 g; the milk group had higher (P<0.0001) calcium intake; s-OC and s-CTX decreased (P