Menopausal women who took soy supplements during a two-year trial reported no differences in quality of life compared to their counterparts taking placebo pills, U.S. researchers report.
It’s possible that soy could still offer women some benefits through menopause, said the study’s lead author Dr. Paula Amato, from Oregon Health and Science University in Portland, “but I think if you are similar to the subjects in the study, then probably taking supplements isn’t going to make a huge impact on your quality of life.”
In light of health concerns attached to taking hormones, soy has been seen as an attractive alternative for relieving menopausal symptoms. But research on the effectiveness of soy extracts for hot flashes and other bothersome symptoms has yielded conflicting results so far.
In the new report, published in the medical journal Menopause, Amato and her colleagues looked not just at specific symptoms but overall quality of life measures among healthy women, mostly in their 50s and six years or more into menopause on average.
Several hundred women were asked to take supplement pills three times a day for two years. Among them, 126 took a fake supplement that contained no soy extract, while 135 women took tablets containing a total of 80 milligrams a day of soy protein and another 123 women took 120 mg each day.
At the start of the study and again one and two years into it, the women filled out a quality of life survey that asked about mental, physical and sexual health as well as about hot flashes.
In each of the surveys, the women in all three groups scored similarly on the main measures in the questionnaire.
“From our study and the good amount of the literature to date it appears that taking soy supplements after menopause does not improve quality of life,” said Amato. “We can’t really recommend it to our patients.”
SOY AND MENOPAUSE
With all that we know about the pitfalls of conventional medicine’s treatment of women in menopause, it makes sense that women are turning to natural approaches to relieve menopausal discomforts. The beneficial effects of estrogen on these discomforts are indisputable, but as women become more informed they see that the risks – especially of breast cancer – may be too great to justify its use. Others stop using conventional HRT because of side effects, and look to natural remedies to help them control their menopause symptoms.
This growing interest in natural solutions for treating menopausal symptoms has prompted the food and supplement industries to develop alternatives to conventional pharmaceutical estrogens such as Premarin. The soy foods industry has been poised to benefit most from this search for natural remedies for menopause because of soy’s high phytoestrogen content.
The lay press and the soy industry have widely promoted the message that soy phytoestrogens act, in effect, as surrogate estrogens. Such a message gives women the impression that they can use soy to naturally relieve symptoms of falling estrogen levels at menopause. While the research does show that isoflavones behave like estrogens in the body the conclusion that they are all the medicine a woman needs to help her through menopause is not borne out by recent clinical studies on soy and menopausal symptoms.
Soy phytoestrogens have very little effect on vasomotor symptoms such as hot flashes, night sweats and vaginal dryness. In one comprehensive study from the Bowman Gray School of Medicine in North Carolina, researchers looked at the effects of soy phytoestrogens on women aged 45 to 55 with menopausal symptoms. This study was big news because the women who took a phytoestrogen-rich soy supplement reported a 50 percent decrease in the severity of their hot flashes. What most news stories didn’t mention, however, is that the placebo group reported a 35 percent reduction. Furthermore, this study showed small reductions in the severity of hot flashes, but none on their frequency. In other words, these women were having just as many hot flashes as they did before they added soy foods or supplements, but the intensity of those hot flashes were diminished. While decreased intensity is certainly a good thing when it comes to hot flashes, soy estrogens are clearly not as potent as many forms of conventional estrogen replacement which often eliminate hot flashes quickly and completely.
A recent study of women with vasomotor symptoms at the Mayo Clinic showed no benefits from soy protein isolates, which have high levels of phytoestrogens. This has also been Dr. Zava’s experience in analyzing saliva hormone level results accompanied by detailed questionnaires; soy phytoestrogens simply don’t work well to control vasomotor symptoms. The isoflavones in soy are aromatase inhibitors which lower the levels of estrogens made by the body, which is counter-productive to controlling vasomotor symptoms.
Mark Messina, president Nutrition Matters and an adjunct professor at Loma Linda University in California, cautioned against concluding that the key ingredients in soy supplements, known as isoflavones, don’t have any effect on hot flashes, however.
“Unfortunately, because of the severe limitations of this study, very little if anything can be learned about isoflavones and hot flashes,” Messina wrote in an email to Reuters Health.
For one, he said, the levels of a particular type of isoflavone - called genistein - were lower than in other studies that have found benefits from soy extracts.