Effect of milk proteins on linear growth and IGF variables in overweight adolescents.
OBJECTIVE
Milk may stimulate growth acting via insulin-like growth factor-I (IGF-I) secretion but the effect in adolescents is less examined. This study investigates the effect of milk proteins on linear growth, IGF-I, IGF binding protein-3 (IGFBP-3) and IGF-I/IGFBP-3 ratio in overweight adolescents.


METHODS
The trial included 193 overweight adolescents aged 12-15 years. They were randomized to drink 1L/day of: skimmed milk, whey, casein or water for 12 weeks; all milk-based drinks contained 35 g protein/L. A subgroup of 32 adolescents was examined 12 weeks before they were randomized into the groups and started the intervention (pre-test control group). Examinations included anthropometry, diet registration and blood samples which were analyzed for IGF-I and IGFBP-3 by chemiluminescence methods. The effects of milk-based drinks on linear growth, IGF-I, IGFBP-3 and IGF-I availability, calculated as the IGF-I/IGFBP-3 ratio, were compared with baseline, the pre-test control group and water.


RESULTS
IGF-I increased with skimmed milk (P=0.015) and tended to increase with casein (P=0.075) compared to the pre-test control group. IGFBP-3 but not IGF-I increased with skimmed milk (P=0.006) and casein (P=0.001) compared to water. There was no difference in height or height Z-score for any of the milk-based test drink groups compared to water or compared to the pre-test control group. However, height Z-score decreased within the whey group.


CONCLUSIONS
Skimmed milk and casein may have a stimulating effect on the IGF-I system whereas there was no positive effect on height in overweight adolescents during this 12 week intervention.
The Department of Nutrition, Exercise and Sports, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark. Electronic address: ala@life.ku.dk.
Anni
A
Larnkjær
The Department of Nutrition, Exercise and Sports, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark.
Karina
K
Arnberg
The Department of Nutrition, Exercise and Sports, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark.
Kim F
KF
Michaelsen
The Department of Nutrition, Exercise and Sports, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark.
Signe M
SM
Jensen
The Department of Nutrition, Exercise and Sports, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg, Denmark.
Christian
C
Mølgaard
D000293:Adolescent; D041923:Adolescent Development / Q000187:drug effects*; D001827:Body Height / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002648:Child; D002657:Child Development / Q000187:drug effects; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008894:Milk Proteins / Q000494:pharmacology*; D050177:Overweight / Q000097:blood / Q000503:physiopathology
D008894:Milk Proteins; D007334:Insulin-Like Growth Factor I
Casein; Height; IGF-I; IGFBP-3; Linear growth; Milk; Whey