The effect of isoflavones extracted from red clover (Rimostil) on lipid and bone metabolism.

OBJECTIVE

This study was undertaken to evaluate the effects of varying doses of phytoestrogens on lipid and bone metabolism in postmenopausal women.

DESIGN

A novel red clover isoflavone preparation (Rimostil) containing genistein, daidzein, formononetin, and biochanin was administered to 46 postmenopausal women in a double-blind protocol after a single-blind placebo phase and followed by a single-blind washout phase. Patients were randomized to receive either 28.5 mg, 57 mg, or 85.5 mg of phytoestrogens daily for a 6-month period.

RESULTS

At 6 months, the serum high-density lipoprotein cholesterol had risen significantly by 15.7-28.6% with different doses (p = 0.007, p = 0.002, p = 0.027), although the magnitude of the response was independent of the dose used. The serum apolipoprotein B fell significantly by 11.5-17.0% with different doses (p = 0.005, p = 0.043, p = 0.007) and the magnitude of the response was independent of the dose used. The bone mineral density of the proximal radius and ulna rose significantly by 4.1% over 6 months with 57 mg/day (p = 0.002) and by 3.0% with 85.5 mg/day (p = 0.023) of isoflavones. The response with 28.5 mg/day of isoflavones was not significant. There was no significant increase in endometrial thickness with any of the doses of isoflavone used.

CONCLUSION

These results show that the administration of an isoflavone combination extracted from red clover was associated with a significant increase in high-density lipoprotein cholesterol, a significant fall in apolipoprotein B, and a significant increase in the predominantly cortical bone of the proximal radius and ulna after 6 months of treatment. Interpretation of the results is undertaken cautiously because of the absence of a simultaneously studied control group.