Soymilk intake is associated with plasma and liver lipid profiles in rats fed a high-cholesterol diet

Effect of probiotic-fermented, genetically modified soy milk on hypercholesterolemia in hamsters

BACKGROUND/PURPOSE

The rapid progress of biotechnology and molecular biology has led to genetically modified (GM) crops becoming a part of agricultural production. There are concerns that the issues of the functional ingredients in GM products have not been addressed, such as the bioactivities of soy proteins and isoflavones. This study aimed to investigate the effects of probiotic-fermented GM soy milk on hypercholesterolemia, and atherosclerotic risks in hamsters.

METHODS

One hundred and twelve male Golden Syrian hamsters (Mesocricetus auratus) were randomly assigned into 14 groups of 8 animals each. Normal- and high-cholesterol experimental diets were supplemented with GM or non-GM soy milk with or without probiotic-fermentation for 8 weeks. Serum and fecal lipid levels were measured. Moreover, aortic plaque in artery were stained, and thiobarbituric acid reactive substance content, super oxide dismutase activity and caralase activity were determined.

RESULTS

GM or non-GM soy milk with or without probiotic-fermentation significantly decreased (p < 0.05) serum TC levels, compared with a high-cholesterol diet group. TC levels in hamsters fed GM soy milk were not significantly different from TC levels in the non-GM soy milk group (p > 0.05). GM soy milk groups can reduce risk of developing atherosclerosis through lowered oxidative stress and reduced atherosclerotic plaque formation in the aorta, and are thus at least equivalent to non-GM soy milk.

CONCLUSION

GM soy milk with or without probiotic-fermentation can improve hypercholesterolemia and reduce the risk of atherosclerosis, and is considered substantially equivalent to non-GM soy milk in terms of these bioactive functions.

Hypocholesterolemic effects of lactic acid-fermented soymilk on rats fed a high cholesterol diet

The effect of fermented soymilk on rats fed a high cholesterol diet was investigated to clarify the cholesterol-lowering function. Male Sprague-Dawley rats aged 7 weeks were fed a control diet (1% cholesterol, high cholesterol diet), high cholesterol diet containing 11.7% fermented soymilk diet (5% soy protein as final concentration, F-5), or high cholesterol diet containing 23.4% fermented soymilk diet (10% soy protein as final concentration, F-10) for 5 weeks. The liver weight and fat mass were decreased by the ingestion of fermented soymilk. The hepatic triglyceride and cholesterol levels in the F-5 and F-10 groups were significantly lowered compared to those in the control group. The plasma total cholesterol level of the F-10 group was significantly decreased. The expression of SREBP-2, a cholesterol synthesis-related gene, was significantly decreased in liver of the F-5 group, but the expression of CYP7a1, a cholesterol catabolism-related gene, was significantly increased. These results suggest that fermented soymilk can modulate the cholesterol metabolism in rats fed a high cholesterol diet.

Effects of lactic acid-fermented soymilk on lipid metabolism-related gene expression in rat liver

We examined the effects of lactic acid fermentation of soymilk on the lipid profile and lipid metabolism-related gene expression in rat liver. Male Sprague-Dawley rats aged 7 weeks were fed a control diet (AIN-93), soymilk diet, or fermented soymilk diet for 1 week or 5 weeks. The hepatic triglyceride and cholesterol contents in the soymilk (SM) group and the fermented soymilk (FSM) group were significantly lower than those in the control group after 5 weeks, but these changes had not become apparent until after 1 week. The fatty acid synthesis-related genes were more markedly down-regulated after 1 week than after 5 weeks, whereas the cytochrome p450 family 7 subfamily a polypeptide 1 (CYP7al) gene related to cholesterol catabolism was more markedly up-regulated after 5 weeks than after 1 week. This up-regulation was higher in the FSM group than in the SM group. It is assumed that the bioactive components produced by lactic acid fermentation induced the up-regulation of CYP7a1.

Atherosclerosis-preventing activity of lactic acid bacteria-fermented milk-soymilk supplemented with Momordica charantia

In this study, the milk-soymilk and milk-soymilk supplemented with Momordica charantia , a common oriental vegetable possessing medicinal activities, were fermented by lactic bacteria. The objective of this study was to investigate the effects of milk-soymilk and fermented milk-soymilk with or without M. charantia on atherosclerosis in hyperlipidemic hamsters. Fermented 25% milk and 75% soymilk combinations, supplemented with 1% M. charantia solution, can improve the acceptability of the fermented beverage. A total of 72 male Golden Syrian hamsters were divided into 9 groups (n = 8/group), and experimental diets were provided with a normal diet for the normal group and a high-cholesterol diet for others. The milk-soymilk and fermented milk-soymilk with or without M. charantia were administrated for 8 weeks. The milk-soymilk and fermented milk-soymilk with and without M. charantia were able to significantly decrease (p < 0.05) the serum cholesterol and the atherosclerotic plaque in aorta based on the comparison to the high-cholesterol diet (H) group. The groups on fermented milk-soymilk by Lactobacillus plantarum NTU 102 with or without M. charantia could significantly decrease (p < 0.05) the ratio of low-density lipoprotein cholesterol (LDL-C) to high-density lipoprotein cholesterol (HDL-C). The femented milk-soymilk by Lactobacillus paracasei subsp. paracasei NTU 101 supplemented with M. charantia had an anti-atherosclerotic activity by increasing superoxide dismutase (SOD) and total antioxidant status (TAS) activity of the blood and relieving the degree of thiobarbituric acid reactive substances (TBARS) compared to the other treatments. It is concluded that the milk-soymilk and the fermented milk-soymilk supplemented with or without M. charantia by L. paracasei subsp. paracasei NTU 101 are effective in preventing and retarding the hyperlipidemia-induced oxidative stress and atherosclerosis.