Anti-hypertensive effect of Korean fermented soybean paste (Doenjang) through regulation of the renin-angiotensin system (RAS) in male rats fed with high-fat and/or high-salt diet

Abstract Background: Korean fermented food, doenjang, is questioned due to its high salt content, although it has been reported an abundance of beneficial effects. Therefore, we investigated its impact on renin-angiotensin system (RAS) hypertension using 3T3-L1 adipocytes and male Sprague-Dawley rats.Results: Among the rats fed with normal diet (ND), high-fat diet (HD), high-fat diet with 8% table salt (HDS), or high-fat diet with doenjang containing 8% table salt (HDJ) for 13 weeks, the HDJ group showed significantly lower blood pressure, lesser body weight, and reduced levels of serum angiotensin II and aldosterone, compared to the HD and HDS groups. In addition, mRNA expressions levels of angiotensinogen, angiotensin converting enzyme, angiotensin II receptor type 1, and angiotensin II receptor type 2 were downregulated in epididymal fat of the HDJ group.Conclusions: In spite of its high salt content, Doenjang appears to inhibit obesity-induced hypertension through modulation of RAS by blocking the angiotensin converting enzyme, even with high fat intake.