title: Associations of total, dairy, and meat protein with markers for bone turnover in healthy, prepubertal boys.
abstract: We previously reported that high intake of milk, but not meat, equal in protein content, increased serum insulin-like growth factor-I (sIGF-I) in prepubertal boys. sIGF-I plays a key role in bone metabolism. Therefore, the aim of this cross-sectional study was to investigate associations of total, dairy, and meat protein intake with markers for bone turnover and sIGF-I in prepubertal, healthy boys (n = 81). We measured bone turnover (enzyme-linked immunoassay) in serum osteocalcin (sOC), bone-specific alkaline phosphatase (sBAP), and C-terminal telopeptide of collagen type-I (sCTX); dietary intake was estimated from a 3-d weighed food record. sIGF-I and its binding protein-3 were assessed (immunoassay) in a subgroup of 56 boys. All statistical models included effects of age, BMI, and energy intake. Dairy protein was negatively associated with sOC (P = 0.05) but not significantly associated with sBAP and sCTX. Further analyses showed that dairy protein decreased (P = 0.05) sOC at a high meat protein intake (>0.8 g/kg), whereas meat protein increased (P = 0.03) sOC at a low dairy protein intake (<0.4 g/kg). Total and meat protein intake was positively associated with sBAP (P < or = 0.04) but not significantly associated with sOC and sCTX. Free sIGF-I was positively associated with total (P < 0.01) and dairy (P = 0.06) protein but not with meat protein. Our results indicate that dairy and meat protein may exhibit a distinct regulatory effect on different markers for bone turnover. Future studies should focus on differential effects of dairy and meat protein on bone health during growth.
authors: Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, 1958 Frederiksberg, Denmark. alzb@life.ku.dk
authors: Alicja Z
authors: AZ
authors: Budek
authors: Camilla
authors: C
authors: Hoppe
authors: Kim F
authors: KF
authors: Michaelsen
authors: Susanne
authors: S
authors: Bügel
authors: Christian
authors: C
authors: Mølgaard
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D016723:Bone Remodeling / Q000502:physiology*; D002648:Child; D024042:Collagen Type I / Q000097:blood; D003430:Cross-Sectional Studies; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008460:Meat; D008894:Milk Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D009994:Osmolar Concentration; D015675:Osteocalcin / Q000097:blood; D010455:Peptides / Q000097:blood; D011627:Puberty / Q000097:blood*
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D004044:Dietary Proteins; D018972:Insulin-Like Growth Factor Binding Protein 3; D008894:Milk Proteins; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D007334:Insulin-Like Growth Factor I; D000469:Alkaline Phosphatase