School-milk intervention trial enhances growth and bone mineral accretion in Chinese girls aged 10-12 years in Beijing. [Prevention of vitamin D deficiency in adolescents and pre-adolescents. An interventional multicenter study on the biological effect of repeated doses of 100,000 IU of vitamin D3]. Factors affecting the morbidity of vitamin D deficiency rickets and primary protection.
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. Recent studies have shown a high prevalence of calcium and vitamin D deficiencies in adolescents. The aim of this present study was to follow the changes in calcium status and 25 hydroxyvitamin D (25[OH]D) and parathyroid hormone (iPTH) levels during winter in preadolescents and adolescents from four university hospitals in northern France.
                Two groups of teenagers and adolescents (range: 10-15 years) were followed from October 1996 to June 1997. They were given either 100,000 IU of vitamin D (treated group n = 33) or a placebo (control group n = 35) in October, January and April. Serum calcium, phosphate, 25(OH)D and iPTH levels were measured at inclusion and every three months thereafter.
                At inclusion, plasma or serum 25(OH)D levels were < or = 10 ng/mL in 16 subjects and < 6 ng/mL in six. In control children, no significant change in 25(OH)D occurred during the study, while plasma or serum iPTH levels increased to 34 +/- 11 pg/mL. In the treated groups, 25(OH)D levels remained > 20 ng/mL in every subject; no hypercalcemia was observed; and the mean plasma or serum iPTH level was 25 +/- 14 pg/mL at the end of the study.
                Teenagers presented with a high prevalence of biological vitamin D deficiency at the end of summer. The increase of iPTH during winter in the unsupplemented group suggests that this has secondary consequences on their calcium homeostasis unless they are supplemented with vitamin D. We advocate a sufficient calcium supply and a 100,000 IU vitamin D supplement given two or three times during winter to preadolescents and adolescents living in northern France. Rickets was investigated in 860 children in the 3 to 36 month age group in 21 villages attached to Sinik Health Centre, in northeastern Turkey. The blood calcium, phosphorus and alkaline phosphatase levels of suspect cases were determined following examination and wrist x-rays taken. The prevalence of cross-sectional rickets was determined, in the cohort group formed by removing the rickets cases (to the first group, advice was not given; to the second, 400 IU of vitamin D) and its incidence determined. The prevalence of rickets was calculated as 9.8% with no distinction observed between males and females (P > 0.05). It is higher in children in the 3-6 month group (23.97%) (P < 0.05); exposed rarely to the sun (P < 0.001); without fish in diet (P < 0.01); born to mother under 18 years old (P < 0.001); with a mother not using contraception (P < 0.01). The prevalence of acute respiratory infections (ARI) was calculated as 47.62% and 35.70% (P < 0.05) in children with and without rickets, respectively. The prevalence of enteritis was calculated as 29.76% and 18.43% (P < 0.05) in children with rickets and without rickets, respectively. Rickets was not seen where 400 IU of vitamin D was administered, while incidence for the twelve-month period was calculated as 3.8% in the other group. Combatting rickets is important in developing countries where deaths under five years are largely due to ARI and enteritis.
There a only few studies on the prevention of nutritional rickets in term born children. Until new data become available, it appears sound to offer preventive measures (vitamin D or calcium) to groups of high risk, like infants and toddlers; children living in Africa, Asia or the Middle East or migrated children from these regions into areas where rickets is not frequent. Due to a marked clinical heterogeneity and the scarcity of data, the main and adverse effects of preventive measures against nutritional rickets should be investigated in different countries, different age groups and in children of different ethnic origin.