Soy Intake and the Maintenance of Peak Bone Mass in Hong Kong Chinese Women

Abstract

Our previous study on bone health among premenopausal women showed that bone mass consolidation is attained by the early 30s, and small loss of spinal bone mineral density (SBMD) occurs soon after peak bone mass attainment. Recent interest has been shown in the potential beneficial effects of phytoestrogens on bone health. However, data are lacking, particularly in Asian women. This study aims to investigate the effect of soy isoflavones intake on the maintenance of peak bone mass in a cohort of 132 women aged 30 -40 years 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 soy foods and other key nutrients, including dietary calcium, were obtained through a quantitative food frequency method. Information on body measurements; physical activity (PA), weight-bearing activity in particular; age of menarche; and number of pregnancies were obtained at baseline. Repeated measurements of SBMD were obtained yearly for a further 3 years with an average follow-up time of 38 months. Analyses were performed on 116 subjects with at least three SBMD measurements (at baseline, 3-year follow-up, and at least one measurement during follow-up). The individual SBMD regression slope was computed for each of the subjects. Soy isoflavones consumption was categorized 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 isoflavones on SBMD remained after adjusting for age and body size (height, weight, and bone area). Multiple linear regression analysis including the other known covariates (lean body mass, PA, energy adjusted calcium, and follow-up time) showed that soy isoflavones, together with these variables, accounted for 24% of the variances of the SBMD individual regression slope. This longitudinal study shows that soy intake had a significant effect on the maintenance of SBMD in women aged 30 -40 years. The effects of phytoestrogens on bone health should be explored further in a population with habitual dietary soy but low calcium intake.

Effect of Soybeans and Sword Beans on Bone Metabolism in a Rat Model of Osteoporosis

“…These results are consistent with those of Potter et al [33] who reported that in postmenopausal women supplemented with isoflavones (90 mg/day), BMD and BMC significantly increased in the lumbar spine. Moreover, epidemiological studies indicated that isoflavonecontaining soy intake had a positive effect on the reduction in spinal bone loss in perimenopausal women [34] . The femur and spine in the OVX rats had lower BMD and BMC values than those of the sham-operated rats, but administration of isoflavone extract was shown to prevent bone loss in the femur and lumbar spine [32] .…”

Soy Isoflavones and Osteoporotic Bone Loss: A Review with an Emphasis on Modulation of Bone Remodeling

“…A study conducted in Hong Kong suggested that there are different effective dosages of soy intake in females aged 30-40 years compared to 60-year-old females, which indicates that older people might need more soy intake to maintain the lumbar BMD. 85 Studies also presented that SI had a comparable positive protective effect on bone loss among younger postmenopausal women who had last menstruation within 7.5 years. 86 Since there is a rapid bone loss period from 12 to 60 months after the last period, because of the acute loss of estrogen, SI have not shown significant effects in early postmenopausal women with higher estrogen levels.…”

Effect of Polyphenols on Calcium Content and Alkaline Phosphatase Activity in Rat Femoral Tissues in Vitro.

“…Recently, genistein has been demonstrated to have an anabolic effect on bone metabolism, suggesting its role in the prevention of osteoporosis. [10][11][12][13][14] Genistein has a stimulatory effect on bone formation and mineralization in tissue culture systems in vitro, [15][16][17] and it can stimulate protein synthesis in osteoblastic cells. [18][19][20] Moreover, genistein has been shown to inhibit osteoclastic bone resorption by preventing the formation and differentiation of osteoclast-like cells from bone marrow cells, 21,22) and the apoptosis of mature osteoclasts is induced by genistein through the Ca 2ϩ signaling mechanism.…”