Results from a recently conducted Italian study confirm the effectiveness of soy isoflavones for alleviating menopausal symptoms. One hundred and thirty healthy postmenopausal women who were experiencing menopausal symptoms were assigned to two groups. Half of the women received a supplement containing an amount of soy isoflavones equal to what would be provided by about two to two-and-one-half servings of traditional soyfoods per day. The other women were given a placebo consisting of calcium and vitamin D.
Clinical trials evaluating hot flashes typically use pills rather than foods because it allows both the researchers and the study participants to be blinded. That is, they don’t know who is in the treatment group and who is getting a placebo. It also improves compliance. That’s especially important in this study since soyfoods are not a usual part of Italian diets.
Menopausal symptoms were evaluated every three months over a period of a year. The difference in symptoms was evident at the first examination. Hot flashes were reduced by 34.4% in the group consuming isoflavones but by only 2.7% in the placebo group. The difference was highly statistically significant, which means the findings were unlikely to have occurred just by chance. Over a longer period of time, the difference between groups actually increased. After one year, symptoms were reduced by 50.3% in the isoflavone group and by 7.9% in the placebo group. Women consuming the isoflavone supplements also experienced improvements in vaginal dryness and libido (sexual drive).
The researchers also assessed the safety of isoflavone supplements by measuring breast tissue density (through mammograms), endometrial thickness and liver function. Breast tissue density is an indicator of breast cancer risk; women with more dense breasts are more likely to develop breast cancer. Similarly, endometrial thickness is a measure of endometrial cancer risk. The researchers found no effects of isoflavones on any of these measures.
In one way, this study was different from others that have looked at isoflavones and menopause symptoms. The women taking isoflavone supplements also took supplements of Lactobacillus sporogenes, a type of healthy gut bacteria, which the researchers speculated could improve absorption of the isoflavones. However, it isn’t evident that these friendly bacteria had the desired effect because the results of this study are similar to other research that has examined the effects of isoflavones alone.
The authors concluded that soy isoflavones can effectively and safely be used at the recommended dose in postmenopausal women. They can be a good choice for women who are unable or unwilling to use hormone therapy for menopause symptoms.
Colacurci N, De Franciscis P, Atlante M, et al. Endometrial, breast and liver safety of soy isoflavones plus Lactobacillus sporogenes in post-menopausal women. Gynecol Endocrinol 2012.