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.


METHODS
A University department.


METHODS
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.


METHODS
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< or =0.04) in the milk group (-30.9%; -18.7%, respectively) compared with the meat group (+6.4%; -1.0%, respectively) and s-BAP decreased (P=0.06) both in the milk (-3.9%) and the meat group (-7.5%).


CONCLUSIONS
At the equal protein intake, milk, but not meat, decreased bone turnover in prepubertal boys after 7 days. This effect was probably due to some milk-derived compounds, rather than to the total protein intake. Future studies should elucidate the mechanism(s) of milk-related decline of bone turnover and its relevance for peak bone mass during growth.


BACKGROUND
University PhD scholarships.
Budek
A Z
AZ
Department of Human Nutrition, Faculty of Life Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg, Denmark. alzb@kvl.dk
Hoppe
C
C
Michaelsen
K F
KF
Mølgaard
C
C
D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D015415:Biomarkers / Q000097:blood; D015519:Bone Density; D016723:Bone Remodeling / Q000187:drug effects* / Q000502:physiology; D001842:Bone and Bones / Q000378:metabolism*; D002648:Child; D024042:Collagen Type I / Q000097:blood; D004044:Dietary Proteins / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008460:Meat; D008894:Milk Proteins / Q000494:pharmacology*; D015675:Osteocalcin / Q000097:blood; D010455:Peptides / Q000097:blood; D011627:Puberty / Q000097:blood / Q000502:physiology
D015415:Biomarkers; D024042:Collagen Type I; D004044:Dietary Proteins; D008894:Milk Proteins; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D000469:Alkaline Phosphatase