Childhood adiposity, adult adiposity, and bone health

Importance:Childhood and adolescence are critical periods for lifelong bone mineral accrual,but few studies have determined the impact of childhood adiposity on adult bone density.Objective:To determine the long-term impact of childhood adiposity on adult areal bone mineral density(aBMD)and the effect of adult adiposity on this relationship.Methods:We conducted a longitudinal study of 1156 adults(56.3%men),for whom skinfold thickness(SFT)had been measured during childhood(6-18 years)and fat mass percentage(FMP)and aBMD were measured during adulthood(29-43 years).Adult aBMD in the lumbar spine(LS),femoral neck(FN),arms,and legs was measured using dual-energy X-ray absorptiometry.The direct effect of childhood SFT and its indirect effect through adult FMP on adult aBMD were estimated using general linear regression and a causal steps approach.Results:Significant positive associations between childhood SFT and adult aBMD were found in the LS in men(β=0.089,P=0.044)and in all the skeletal sites in women.With respect to the adult fat-bone relationship,high adult FMP was associated with low aBMD in most of the sites in men,but with high FN aBMD in women(β=0.144,P=0.002).Moreover,suppressive effects of adult FMP on the associations between childhood SFT and adult aBMD in the LS(-34.8%)and legs(-67.1%)of men,and a positive effect on the FN aBMD in women(17.0%)were identified.Interpretation:Childhood adiposity appears to have a positive long-term effect on adult aBMD,which may be reduced by adiposity in adult men but reinforced by adiposity in adult women.