薬理と治療

Abstract

Objective　Rice koji is a solid state-culture of a koji mold, Aspergillus oryzae, on steamed rice which has long been used for producing various Japanese traditional fermented foods. The present clinical study was aimed to examine the hypoglycemic effects of commercial product of salted rice koji（shiokoji）, a popular seasoning in Japan, in mildly hyperglycemic adults. Methods　This randomized, double-blind, placebo-controlled parallel-group study included 48 healthy adult subjects with normal-high or marginally high fasting blood glucose（FBG）levels（100-125 mg/dL）. The subjects were randomly assigned to receive either shiokoji（15 g╱day）or placebo for 12 weeks and the groups were compared（the primary analysis）. We assessed the effects of shiokoji supplementation on the FBG level, as well as on the two other glucose metabolism parameters, HbA1c and HOMA-IR, after 4, 8, and 12 weeks of treatment. However, this population included 18 subjects who were judged ineligible for efficacy evaluation because of impaired lifestyle and╱or high insulin resistance. Thus, efficacy evaluation was also conducted in the residual 30 subjects （the secondary analysis）. Results　Data from the secondary analysis but not the first analysis showed that shiokoji supplementation lowered the FBG levels over the treatment period. Additionally, between-group differences in the magnitude of changes in the FBG levels at week-4 and week-12 significantly and near-significantly, respectively, favored shiokoji supplementation. Shiokoji was well-tolerated, and no untoward side effects nor laboratory abnormalities were observed during the treatment. Conclusion　Our findings suggest that shiokoji supplementation is effective for lowering FBG levels in mildly hyperglycemic adults. This study is registered with UMIN Clinical Trials Registry（ID: UMIN000028238）.