Doenjang, a Korean fermented soy food, exerts antiobesity and antioxidative activities in overweight subjects with the PPAR-γ2 C1431T polymorphism: 12-week, double-blind randomized clinical trial.

ABSTRACT

We examined the antiobesity and antioxidant effects of supplementation with doenjang, a fermented soybean paste, in overweight Koreans with the PPAR-γ2 C1431T polymorphism. Sixty overweight subjects were randomly assigned to consume either 9.8 g/day of doenjang or placebo for 12 weeks. Before and after the intervention, anthropometric and metabolic parameters, along with abdominal fat distribution and PPAR-γ2 polymorphisms, were measured. Fifty-one subjects completed the study, doenjang (n=26) and placebo (n=25) groups. Relative frequencies of the PPAR-γ2 genotypes CC, TC, and TT were 70% (n=41), 25.9% (15), and 3.4% (2), whereas those of the PPAR-γ2 alleles C and T were 81.6% and 18.4%. Visceral fat area (VFA) was significantly decreased by doenjang supplementation in subjects with a mutant T allele of PPAR-γ2 compared to those with a C allele after adjusting for age, sex, and body mass index. Plasma free fatty acid, insulin, and homeostatic model assessment insulin resistance (HOMA-IR) levels were also significantly increased in the doenjang group. Doenjang pills significantly activated radical clearance capacity (ORAC and DNA tail length) in subjects with the C allele. The catalase (CAT) activity was increased twofold in the doenjang-treated group with the C allele, but this phenomenon was reversed in those with the T allele. Doenjang-treated subjects tended to have low dietary carbohydrate and sodium intakes compared with those given placebo. We found that doenjang supplementation decreased visceral fat accumulation and aging most effectively in subjects with PPAR-γ polymorphisms. This study suggests that doenjang has antiobesity and antioxidative effects in overweight individuals with mutant alleles of PPAR-γ2.