Fermentation improved gene modulatory effects of soy milk to lower serum triglyceride and elevate HDL‐cholesterol in SD rats on high cholesterol diets.

Abstract

Soy is known to improve blood lipid profiles and fermentation was implicated to increase bioavailability of isoflavones. Here we aimed to investigate the effects of soy milk (SOY) or fermented soy milk (FSOY) on lipid profiles and expression of genes in cholesterol and triglyceride (TG) metabolism in rats fed high cholesterol diets : Control AIN76A diet, high cholesterol (CHOL) diet containing 1% cholesterol, SOY diet (a CHOL diet with SOY substituting 20% of casein), and FSOY diet (a CHOL diet with FSOY substitution). We examined blood lipid profiles, lipid contents in liver and feces, and gene expression levels in liver and adipose tissues. SOY and FSOY lowered liver total cholesterol (TOTAL‐C) compared to CHOL but failed to affect serum TOTAL‐C and LDL‐C. This effect was associated with clear reduction of HMG‐CoAR mRNA levels in FSOY. Serum HDL‐C elevation detected in only FSOY was related to increased ABCA1 mRNA levels in adipose tissue in comparison to CHOL. CHOL‐elevated serum TG levels were markedly reduced by SOY or FSOY, which didn¡ t affect SREBP1c mRNA in the liver. Instead a slight recovery of CHOL suppression of VLDLR, Lrp1, or UCP2 transcript levels in adipose tissues was observed by SOY, which effect was much greater in FSOY. Our data suggested that FSOY may be more effective in improving CHOL‐induced aberrant lipid metabolism than SOY via greater changes in gene expression in liver and adipose tissues.