Xuemei Ao

Background: The effect of calcium supplementation on bone mineral accretion in people under 35 years old is inconclusive. To comprehensively summarize the evidence for the effect of calcium supplementation on bone mineral accretion in young populations (≤35 years). Methods: This is a systematic review and meta-analysis. The Pubmed, Embase, ProQuest, CENTRAL, WHO Global Index Medicus, Clinical Trials.gov, WHO ICTRP, China National Knowledge Infrastructure (CNKI), and Wanfang Data databases were systematically searched from database inception to April 25, 2021. Randomized clinical trials assessing the effects of calcium supplementation on bone mineral density (BMD) or bone mineral content (BMC) in people under 35 years old. Results: This systematic review and meta-analysis identified 43 studies involving 7,382 subjects. Moderate certainty of evidence showed that calcium supplementation was associated with the accretion of BMD and BMC, especially on femoral neck (standardized mean difference [SMD] 0.627, 95% confidence interval [CI] 0.338-0.915; SMD 0.364, 95% CI 0.134-0.595; respectively) and total body (SMD 0.330, 95% CI 0.163-0.496; SMD 0.149, 95% CI 0.006-0.291), also with a slight improvement effect on lumbar spine BMC (SMD 0.163, 95% CI 0.008-0.317), no effects on total hip BMD and BMC and lumbar spine BMD were observed. Very interestingly, subgroup analyses suggested that the improvement of bone at femoral neck was more pronounced in the peripeak bone mass (PBM) population (20-35 years) than the pre-PBM population (<20 years). Conclusions: Our findings provided novel insights and evidence in calcium supplementation, which showed that calcium supplementation significantly improves bone mass, implying that preventive calcium supplementation before or around achieving PBM may be a shift in the window of intervention for osteoporosis. Funding: This work was supported by Wenzhou Medical University grant [89219029].

ABSTRACT Background Traditional metrics such as body mass index (BMI) and waist circumference (WC) fail to accurately assess the health outcomes associated with abdominal adiposity, because they neglect the intricacies of adipose tissue distribution. Notably, the variability in body composition scaled to height remains underexplored in Chinese demographics. This study introduces height‐normalised indices of abdominal adiposity using computed tomography (CT) scans and further assesses their associations with various health outcomes. Methods In a large, diverse Chinese population ( n = 1054 healthy individuals; n = 1159 with dyslipidemia; n = 803 with diabetes; n = 1289 with cardio‐cerebrovascular diseases; n = 1108 with cancers; and n = 509 with abnormal bone mas), abdominal CT scans were performed and allometric growth model analyses were used to derive height‐normalised indices (body composition/height β ). Logistic regression models assessed the associations between these indices and health outcomes. Results Distinct scaling powers were observed for visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and total abdominal adipose tissue (TAT), as well as for sagittal diameter (SAD), with marked sex differences. Powers for VAT were 1.786 ± 1.270 for males and 1.274 ± 0.692 for females. Powers for SAT were 2.266 ± 0.856 for males and 1.656 ± 0.497 for females. Powers for TAT were 2.141 ± 0.967 for males and 1.438 ± 0.489 for females. Powers for SAD were 0.646 ± 0.217 for males and 0.678 ± 0.141 for females. After controlling for age, BMI and WC, VAT/height β , TAT/height β and SAD/height β retained their significantly positive associations with the odds of health outcomes, whereas SAT/height β did not. Conclusions Our findings endorse the clinical utility of height‐normalised indices, particularly VAT/height β , TAT/height β and SAD/height β , in health outcomes assessment. These indices, grounded in robust empirical data, underscore the necessity of a nuanced approach in obesity‐related health evaluations, advocating for a departure from conventional methods like BMI.