Background: Bone mass acquisition during growth is a major determinant of the risk of developing osteoporosis later in life. Body composition is an anthropometric determinant of bone mineral density (BMD) and significantly influences its development during childhood and adolescence. Objective: This study aimed to systematically examine the association between body composition and bone mineral density in children and adolescents. Methods: Observational studies addressing this association were identified from PubMed (MEDLINE), Embase, Scopus and the Cochrane Library (up to January 2021). The study populations consisted of healthy children and adolescents. The DerSimonian and Laird method was used to compute pooled estimates of effect size and the respective 95% confidence intervals for upper limbs, femoral neck (FN), lumbar spine (LS) and total body, respectively. Subgroup analyses were further performed based on age, sex and ethnicity. Results: Thirty-one published studies were eligible for inclusion in this systematic review and meta-analysis, including three longitudinal studies. The combined population from all the studies amounted to 21,393 (11,205 males and 10,188 females). The pooled estimates of the correlation coefficients for lean mass (LM) and BMD ranged from 0.53 to 0.74 (p < 0.050), and the pooled regression coefficients ranged from 0.23 to 0.79 for FN, LS and total body (p < 0.050). For fat mass (FM), the pooled correlation coefficients ranged from 0.10 to 0.50 (p < 0.050) and the pooled regression coefficient was only significant for FN BMD with a weak strength (pooled β = 0.07, p < 0.050). The pooled regression coefficients for body fat percentage (BF%) were between −0.54 and −0.04 (p < 0.050). The subgroup analysis revealed a stronger association in Asians than in Caucasians for LM and in males compared to females for BF% (p < 0.050). Conclusions: This systematic review and meta-analysis supports a positive association between LM and BMD. BF% appears to have a deleterious effect on bone acquisition in children and adolescents.

Background: Bone mineral acquisition during adolescence is crucial for maximizing peak bone mass. Fat mass (FM) and bone mass are closely related. This study investigated the association of FM distribution with bone mass in Chinese male adolescents. Method: A total of 693 male adolescents aged 10–18 years were recruited from a secondary school in Jiangmen, China. Their bone mass and body composition were measured by quantitative ultrasound and bioelectrical impedance analysis, respectively. The associations of the measures of fat distribution with bone parameters, i.e., broadband ultrasound attenuation, speed of sound (SOS), and stiffness index (SI), were analyzed using multiple linear regression. Age, height, body mass index, stage of puberty, physical activity, sedentary behavior, dietary energy intake, and dietary calcium and vitamin D intake were adjusted in the model. Further subgroup analyses of prepubertal and pubertal participants were conducted. Results: The measures of fat distribution showed negative associations with SOS and SI in total subjects (p < 0.010). In prepubertal boys, the measures of fat distribution were only associated with SOS (β = −0.377 to −0.393, p < 0.050). In pubertal boys, the measures of fat distribution had associations with all bone parameters (β = −0.205 to −0.584, p < 0.050). The strongest association was between trunk FM and SOS (β = −0.584, p < 0.001). Conclusion: This study supported that the measures of fat distribution were negatively associated with bone parameters in Chinese male adolescents. Trunk FM had the strongest association with bone parameter. These associations appear to be stronger in pubertal boys than in prepubertal boys.

(1) Background: Optimal bone mass accumulation during adolescence is crucial for maximising peak bone mass during adulthood. Dietary antioxidant vitamins may contribute to bone mass accumulation. This 2.5-year-long longitudinal study aimed to evaluate the relationships between dietary vitamin A, C, and E intakes and the annual changes in bone parameters among Chinese adolescents. (2) Method: Subjects aged 10–18 years (n = 1418) were recruited from a secondary school in Jiangmen, China. Dietary vitamin A, C, and E intakes were assessed using 24 h dietary records over 3 consecutive days. The Sahara Clinical Bone Sonometer was used to measure the broadband ultrasound attenuation (BUA) and the speed of sound (SOS). Their annual changes were then calculated (i.e., BUA%/year, SOS%/year). The associations were detected after adjusting for the baseline bone phenotype; age; sex; weight; height; pubertal stage; physical activity; and dietary intakes of vitamin D, calcium and energy. (3) Results: A curvilinear relationship was found between the dietary intake of vitamin C and BUA%/year (p = 0.026); further analyses in the subgroups revealed that this relationship was observed in male adolescents (p = 0.012). A positive association was observed only in boys with a dietary vitamin C intake of ≥159.01 mg/day (β = 0.395, p = 0.036). Moreover, a linear positive association was shown between the dietary intake of vitamin E and BUA%/year in female adolescents (β = 0.082, p = 0.033). (4) Conclusion: Our findings indicated that dietary vitamin C intake has a threshold effect on bone mass gain in male adolescents and that dietary vitamin E intake could be a positive predictor of bone mass gain in female adolescents.