Effects of natural S-equol supplements on overweight or obesity and metabolic syndrome in the Japanese, based on sex and equol status


Correspondence: Takeshi Usui, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, 1-1 Mukaihata-cho Fukakusa Fushimi-ku, Kyoto 612-8555, Japan. Tel.: +81 75 641 9161; Fax: +81 75 645 2781; E-mail: tusui@kuhp.kyoto-u.ac.jp



Epidemiologic studies indicate that soy intake has an important role in the prevention of age-related health problems. Daidzein, the principal isoflavone contained in soy, is converted to S-equol by the intestinal bacteria. Not all individuals, however, can produce S-equol, which is considered the most biologically active metabolite. We studied the effects of a natural S-equol supplement on metabolic parameters associated with overweight or obesity and metabolic syndrome.


The study was a randomized, double-blinded, placebo-controlled, crossover design with no washout period. All subjects were considered overweight or obese if they had a body mass index ≧25 kg/m2. Placebo or natural S-equol tablets containing 10 mg S-equol were orally ingested each day for 12 weeks. A total of 54 Japanese overweight or obese outpatients were enrolled. The equol phenotype was determined, and various metabolic parameters, including cardio-ankle vascular index (CAVI), were measured.


Equol non-producers comprised 67·9% of the overweight or obese subjects. The ratio of equol non-producers in this overweight or obese subject group was higher than the previously reported ratio of equol non-producers (approximately 50%) in the general population. Compared with the placebo group, intervention with natural S-equol led to a significant decrease in HbA1c, serum low-density lipoprotein cholesterol (LDL-C) levels and CAVI score. Furthermore, the effect was more prominent in the subgroup of female equol non-producers.


The ratio of equol non-producers in overweight or obese populations might be higher than generally reported. Natural S-equol might have a role in glycaemic control and in the prevention of cardiovascular disease by its effects to lower LDL-C levels and CAVI scores in overweight or obese individuals.