Positive Health Online

Abstract

GALLAGHER and colleagues, Bone Metabolism Unit, School of Medicine and the Osteoporosis Research Center, Creighton University, Omaha, NE, USA, jcg@creighton.edu, have studied the effect of soy isolates on bone metabolism.

Background

The aim of this study was to investigate the effect of soy protein isolate with varying concentrations of isoflavones on early postmenopausal bone loss and lipids.

Methodology

In this 15-month, double-blinded pilot study, 55 post-menopausal women were randomized to three groups to receive either soy protein with 96 mg isoflavones, soy with 52 mg isoflavones, or soy without isoflavones (< 4 mg isoflavones). Soy was given daily for 9 months. The subjects were followed up for 6 months after the end of the trial. Bone mineral density and blood lipids were measured during this time.

Results

Results: Measurement of serum isoflavones at 3 months showed dose-related increases in all three groups. There was no significant effect of the soy supplements on bone mineral density of the spine or femoral neck in any of the three groups. Bone mineral density increased significantly in the femoral neck at 9 months (P = 0.0219) and at 15 months (P < 0.05) in the group given isoflavone-free soy compared with the other two groups. There was no significant effect of soy on lipid metabolism at the end of the intervention.

Conclusion

The present study did not find a significant positive effect of soy protein isolate supplemented with isoflavones on bone density in early postmenopausal women.

References

Gallagher JC, Satpathy R, Rafferty K, Haynatzka V. The effect of soy protein isolate on bone metabolism. Menopause 11(3): 290-298, May-Jun 2004.