Phytoestrogens: The jury is still out
A meta-analysis of 43 RCTs (4364 patients) evaluated phytoestrogens that included dietary soy, soy extracts, red clover extracts, genistein extracts, and other types of phytoestrogens.3 The data from the only 5 RCTs (300 patients) that could be combined showed no effect from red clover extract on hot flash frequency. However, another 4 individual trials that couldn’t be combined each found that extracts with high levels of the phytoestrogen genistein (>30 mg/d) did reduce frequency. Investigators reported that many of the trials were small and had a high risk of bias.
A meta-analysis of 16 RCTs (2027 patients) that assessed black cohosh found that it didn’t reduce hot flash frequency (3 RCTs, 393 patients) or symptom severity scores (4 RCTs, 357 patients).4 Investigators reported high heterogeneity and recommended further research.
Nonpharmacologic therapies and vitamin E don’t help
Systematic reviews found that relaxation therapy (4 RCTs, 281 patients), exercise (3 RCTs, 454 patients), and acupuncture (8 RCTs, 414 patients) didn’t reduce hot flashes.5-7 In another review, vitamin E (1 RCT, 105 patients), homeopathy (2 RCTs, 124 patients), and magnetic devices (1 RCT, 11 patients) also produced no benefit.1