Association between equol and non‐alcoholic fatty liver disease in Japanese women in their 50s and 60s

Abstract Background and Aim Equol is a metabolite of soy isoflavone and has estrogenic activity. The incidence of non‐alcoholic fatty liver disease (NAFLD) increases after menopause in women, which is thought to result in a decrease in estrogen. This study aimed to evaluate the association between equol and NAFLD. Methods We evaluated 1185 women aged 50–69 years who underwent health check‐ups at four health centers in Fukushima, Japan. Equol producers were defined by a urinary equol concentration of 1.0 μM or more. In addition to comparison between equol producers and non‐producers, the association between equol and NAFLD was estimated using logistic regression analysis adjusting for fast walking and eating habits. Results Of the 1185 participants, 345 (29.1%) women were equol producers. The proportions of women who had NAFLD (34.8% vs 45.2%) were significantly lower in the equol‐producing group than in the non‐producing group. Multivariable logistic regression analysis showed that equol production was significantly associated with NAFLD (odds ratio = 0.66, 95% confidence interval: 0.51–0.86). Conclusions Equol production was significantly associated with NAFLD in women in their 50s and 60s.