A high
cholesterol diet induces
dyslipidemia. This study investigated whether
isoflavone aglycones in
lactic acid-fermented soy milk (LFS) improve lipid metabolism in rats fed a high
cholesterol diet. Male Sprague-Dawley rats aged seven weeks were fed an AIN-93G diet, a 1%
cholesterol diet (a high
cholesterol diet), a high-
cholesterol diet containing 4%
isoflavone extract of LFS (LFS extract diet), a high-
cholesterol diet containing 19.4%
ethanol-washed LFS (
ethanol-washed LFS diet,
isoflavone-poor diet), or a high
cholesterol diet containing 23.2% intact LFS (intact LFS diet) for five weeks. The plasma total
cholesterol (TC) level was increased in the rats fed the LFS extract diet compared with those fed the high
cholesterol diet. The TC level was decreased by the intact LFS and
ethanol-washed LFS diets. The
cholesterol-lowering effect was stronger in the rats fed the intact LFS diet than those fed the
ethanol-washed LFS diet. The plasma
triglyceride (TG) level was unchanged in the rats fed the LFS extract diet, but it decreased in rats fed the intact LFS and
ethanol-washed LFS diets. Although, compared with the high
cholesterol diet, the LFS extract and
ethanol-washed LFS diets did not reduce hepatic
cholesterol and TG, both levels were remarkably lowered by the intact LFS diet. These results suggest that the improvement in lipid metabolism of rats fed a high-
cholesterol diet containing LFS
isoflavone aglycones is not due to an independent effect but due to a cooperative effect with
soy protein.