ABSTRACT
BACKGROUND: A 2-y school milk intervention trial showed that 330 mL of a dietary milk supplement (fortified with calcium alone or with both calcium and vitamin D) enhanced the growth and bone mineral accretion of Chinese girls aged 10 y at baseline. Girls who received milk fortified with both calcium and vitamin D also had better vitamin D status than did girls who received nothing or girls who received milk fortified only with calcium. OBJECTIVE: The aim was to evaluate whether these effects were sustained 3 y after supplement withdrawal. DESIGN: Anthropometric measures and dietary intake were reassessed in 501 of the 698 girls whose data had been studied at the end of the intervention. As in the intervention phase, total-body bone mineral content and bone mineral density and serum 25-hydroxyvitamin D concentrations were measured in half of these subjects. RESULTS: At follow-up, 99% of girls had reached menarche, at a mean (+/-SD) menarcheal age of 12.1 +/- 1.1 y. No significant differences in the timing of menarche were observed between the 3 groups (P = 0.6). No significant differences in the changes of total-body bone mineral content and bone mineral density since baseline were observed between the groups. The group receiving calcium-fortified milk had significantly greater gains in sitting height (0.9 +/- 0.3%; P = 0.02) than did the control group. The group that received calcium- and vitamin D-fortified milk had 17.1 +/- 6.7% lower serum 25-hydroxyvitamin D concentrations than did the control group (P = 0.04), but the difference was attenuated by additional adjustment for physical activity level (14.2 +/- 6.7%; P = 0.08). CONCLUSION: Milk supplementation during early puberty does not have long-lasting effects on bone mineral accretion.
Subject(s)
Bone Density/physiology , Calcium, Dietary/administration & dosage , Growth , Milk , Vitamin D/administration & dosage , Vitamin D/blood , Absorptiometry, Photon , Adolescent , Animals , Body Height/drug effects , Body Height/physiology , Body Weight/drug effects , Body Weight/physiology , Bone Density/drug effects , Bone Development/drug effects , Bone Development/physiology , Child , China , Dietary Supplements , Female , Follow-Up Studies , Food, Fortified , Growth/drug effects , Growth/physiology , Humans , Menarche/physiologySubject(s)
Bone Density/physiology , Dietary Supplements , Growth/physiology , Milk , Animals , Body Size/physiology , Cattle , Child , China , Cluster Analysis , Female , HumansABSTRACT
A 2-year milk intervention trial was carried out with 757 girls, aged 10 years, from nine primary schools in Beijing (April 1999 - March 2001). Schools were randomised into three groups: group 1, 238 girls consumed a carton of 330 ml milk fortified with Ca on school days over the study period; group 2, 260 girls received the same quantity of milk additionally fortified with 5 or 8 microg cholecalciferol; group 3, 259 control girls. Anthropometric and bone mineralisation measurements, as well as dietary, health and physical-activity data, were collected at baseline and after 12 and 24 months of the trial. Over the 2-year period the consumption of this milk, with or without added cholecalciferol, led to significant increases in the changes in height (> or =0.6 %), sitting height (> or =0.8 %), body weight (> or 2.9 %), and (size-adjusted) total-body bone mineral content (> or =1.2 %) and bone mineral density (> or =3.2 %). Those subjects receiving additional cholecalciferol compared with those receiving the milk without added 25-hydoxycholecalciferol had significantly greater increases in the change in (size-adjusted) total-body bone mineral content (2.4 v. 1.2 %) and bone mineral density (5.5 v. 3.2 %). The milk fortified with cholecalciferol significantly improved vitamin D status at the end of the trial compared with the milk alone or control groups. It is concluded that an increase in milk consumption, e.g. by means of school milk programmes, would improve bone growth during adolescence, particularly when Ca intake and vitamin D status are low.
