Soy intake and the maintenance of peak bone mass in Hong Kong Chinese women

Our previous study on bone health among premenopausal women showed that bon e mass consolidation is attained by the early 30s, and small loss of spinal bone mineral density (SBMD) occurs soon after peak bone mass attainment. R ecent interest has been shown in the potential beneficial effects of phytoe strogens on bone health. However, data are lacking, particularly in Asian w omen. This study aims to investigate the effect of soy isoflavones intake o n the maintenance of peak bone mass in a cohort of 132 women aged 30-40 yea rs who were followed up for 3 years. Baseline measurements of SBMD (L2-L4) were obtained using dual-energy X-ray densitometry, and dietary intake of s oy foods and other key nutrients, including dietary calcium, were obtained through a quantitative food frequency method, Information on body measureme nts; physical activity (PA), weight-bearing activity in particular; age of menarche; and number of pregnancies were obtained at baseline. Repeated mea surements of SBMD were obtained yearly for a further 3 years with an averag e follow-up time of 38 months. Analyses were performed on 116 subjects with at least three SBR;ID measurements (at baseline, 3-year follow-up, and at least one measurement during follow-up). The individual SBMD regression slo pe was computed for each of the subjects. Soy isoflavones consumption was c ategorized as quartiles of intake. We observed a significant difference in the SBMD individual regression slopes between women belonging to the fourth and first soy isoflavones intake quartiles, The positive effect of soy iso flavones on SBMD remained after adjusting for age and body size (height, we ight, and bone area). Multiple linear regression analysis including the oth er known covariates (lean body mass, PG, energy adjusted calcium, and follo w-up time) showed that soy isoflavones, together with these variables, acco unted for 24% of the variances of the SBMD individual regression slope, Thi s longitudinal study shows that soy intake had a significant effect on the maintenance of SBMD in women aged 30-40 years, The;effects df phytoestrogen s on bone health should be explored further in a population with habitual d ietary soy but low calcium intake.