By Chen YM, Ho SC, et al, Hong Kong, J. of Clinical Endocrinology & Metabolism 88 (2003): 4740-4747 & Menopause 11 (2004), 246-254.;
Chen YM, Ho SC, et al, Hong Kong, Beneficial effect of soy isoflavones on bone mineral content was modified by years since menopause, body weight, and calcium intake: a double-blind, randomized, controlled trial, Menopause 11 (2004), 246-254.
In a one-year study, the effect of SoyLife EXTRA, a 10% isoflavone extract from soy hypocotyl, was tested in a group of postmenopausal women to study its effects on bone health. The composition of the group reflected both early and late menopause, as well as a large variation in initial bone mass.
175 Chinese women aged between 48 and 62, participated in the placebo controlled, doubleblind study. Their last menses had been between 1 and 10 years ago. The women received either one of two isoflavone dosages (40 or 80 mg aglycones daily) or a placebo (corn starch). While establishing the dosage of isoflavones, it was taken into account that on average all women also ingested 20 mg of isoflavones from their Chinese diet. Women also received 500 mg calcium and 125 IU vit. D per day.
Bone mineral concentration (BMC) and density (BMD) of the whole body, the lumbar spine (L1-L4), and the left hip were measured before and after 12 months of treatment. Femur’s neck, trochanter and intertrochanter were also measured. During the trial, a validated questionnaire was used to register physical activity, food consumption and other factors which could influence the relationship between dietary isoflavone consumption and bone mass.
Results and conclusion
This study showed that supplementation of 80 mg of SoyLife isoflavones had a positive effect on BMC. Significant effects were especially found for women with lower BMC at baseline, and occurred at the total hip as well as trochanter and intertrochanter. An increase of 1 mg of isoflavones per day was associated with a yearly increase of 0.018 – 0.028 % of BMC at these bone sites. This increase is worth noting, as it is reported that on average postmenopausal women lose 4%/yr bone mass. Dietary protein intake and mild physical activity also showed beneficial effects on bone. However, these effects were independent from the effects of isoflavones.