Impact of dairy supplementation on bone acquisition in children's limbs: a 12-month cluster-randomized controlled trial and meta-analysis.

The impact of milk on bone health in rural preschoolers is under-researched. This study, through a clinical trial and a meta-analysis, finds that milk supplementation enhances forearm and calcaneus bone acquisition in children, supporting the benefits of daily milk consumption. PURPOSE: This study evaluated the impact of dairy supplementation on bone acquisition in children's limbs through a cluster-randomized controlled trial and a meta-analysis. METHODS: The trial involved 315 children (4-6 year) from Northwest China, randomized to receive either 390 ml of milk daily (n = 215) or 20-30 g of bread (n = 100) over 12 months. We primarily assessed bone mineral density (BMD) and content (BMC) changes at the limbs, alongside bone-related biomarkers, measured at baseline, the 6th and 12th months. The meta-analysis aggregated BMD or BMC changes in the forearm/legs/calcaneus from published randomized trials involving children aged 3-18 years supplemented with dairy foods (vs. control group). RESULTS: Of 278 completed the trial, intention-to-treat analysis revealed significant increases in BMD (4.05% and 7.31%) and BMC (4.69% and 7.34%) in the left forearm at the 6th and 12th months in the milk group compared to controls (P < 0.001). The calcaneus showed notable improvements in BMD (2.01%) and BMC (1.87%) at 6 months but not at 12 months. Additionally, milk supplementation was associated with beneficial changes in bone resorption markers, parathyroid hormone (- 12.70%), insulin-like growth factor 1 (6.69%), and the calcium-to-phosphorus ratio (2.22%) (all P < 0.05). The meta-analysis, encompassing 894 children, indicated that dairy supplementation significantly increased BMD (SMD, 0.629; 95%CI: 0.275, 0.983) and BMC (SMD, 0.616; 95%CI: 0.380, 0.851) (P < 0.05) in the arms, but not in the legs (P > 0.05). CONCLUSION: Milk supplementation significantly improves bone health in children's forearms, underscoring its potential as a strategic dietary intervention for bone development. Trial registration NCT05074836.

Methylobacterium crusticola sp. nov., isolated from biological soil crusts.

A pink-pigmented, Gram-negative, rod-shaped, obligate aerobic bacterial strain, MIMD6T, was isolated from biological soil crusts in PR China. Cells grew at 20-37 °C (optimum, 30 °C), at pH 6-8 (optimum, pH 7) and with 0-1 % (w/v) NaCl (optimum, 0 %). Strain MIMD6T could use methanol or formate as a sole carbon source to grow, and carried methanol dehydrogenase genes mxaF and xoxF, supporting its methylotrophic metabolism. The respiratory quinone was ubiquinone Q-10, the major fatty acids were C18 : 1ω7c (87.3 %), and the major polar lipids were diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unknown aminolipid and one unidentified glycolipid. The results of phylogenetic analyses based on the sequences of the 16S rRNA gene, seven housekeeping genes (dnaK, recA, rimO, rpIK, rpmG, rpsR and rpoB) and methanol dehydrogenase genes indicated that strain MIMD6T formed a phylogenetic linage with members of the genus Methylobacterium. Strain MIMD6T was most closely related to Methylobacterium isbiliense DSM 17168T and Methylobacterium nodulans LMG 21967T with 16S rRNA gene sequence similarities of 95.7 and 95.2 %, respectively. The genomic DNA G+C content calculated via draft genome sequencing was 73.0 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain MIMD6T and the type strains of other Methylobacterium species were 70.7-82.0 and 24.6-30.0 %, respectively. Based on phenotypic, chemotaxonomic and phylogenetic characteristics, strain MIMD6T represents a novel species of the genus Methylobacterium, for which the name Methylobacterium crusticola sp. nov. is proposed. The type strain is MIMD6T (=KCTC 52305T=MCCC 1K01311T).