Relation between premenstrual syndrome and equol-production status

Aim Consumption of isoflavones, which are predominantly derived from soybeans, reduces the risk of estrogen‐related diseases, such as menopausal symptoms, breast cancer, osteoporosis, and cardiovascular disease. Equol is more bioavailable than other soy isoflavones, and equol producers are believed to benefit to a greater extent. This study was conducted to evaluate the relation between premenstrual syndrome (PMS) and equol‐production status in Japanese reproductive‐age women. Methods This was a cross‐sectional, observational study. The study included 144 Japanese women aged 20–45 years. PMS patients (n = 46) were recruited at three obstetrics and gynecology clinics. Control group women (n = 98) who were not receiving therapy for PMS were recruited from the local area by advertisement. The participants’ equol‐production status was determined using urine samples collected after a soy challenge test. Results The prevalence of equol producers was 41.8% in the control group and 23.9% in the patient group (P = 0.042). Using univariate analysis, significant risk factors for equol non‐producers were being a PMS patient and being younger. In multivariate analysis with a step‐wise model, being a PMS patient (odds ratio, 2.342; 95% confidence interval, 1.021–5.698) was shown to be a significant risk factor for being an equol non‐producer. Conclusion This study showed a relation between PMS and equol‐production status in Japanese women.