| The prevalence of type 2 diabetes mellitus (T2DM) is increasing rapidly in the worldwide. Insulin resistance is the determinant factor for the development of type 2 diabetes. It most often precedes the onset of T2DM by many years. High sugar/high fat diets are the dietary causes of T2DM. Vinegar has been demonstrated to have positive effects on lowering postprandial blood glucose response and anti-hyperlipidemia. Acetic acid was regarded as the main effective component in vinegar.In the present study, we studied the effects of acetic acid (the volatile acid in vinegar) on anti-hyperlipidemia in ICR mice fed on a high lipid diet and on insulin sensitivity of rats fed on a modeling diet, which has similar lipid load with the diet of Chinese town residents. We further compared the preventive effects of acetic acid and vinegar powder (the total nonvolatile components in vinegar) on insulin resistance in rats fed on a high fructose diet. We also evaluated the safety of vinegar powder with a human study. The main results summarized as follows:1) ICR mice were fed on a AIN-93G diet, a high lipid diet (15 % soybean oil and 1 % cholesterol) and diets with low (0.1 %), medium (0.2 %) or high (0.4 %) acetic acid concentrations for 3 weeks. High lipid diet increased plasma and liver triacylglycerol (TG), total cholesterol (TC) levels and the ratio of visceral adipose weight to body weight significantly (p<0.05). Compared with high lipid diet group, plasma TG, TC levels and liver TC contents decreased significantly in the medium and high concentration groups (p<0.05). Plasma TC also decreased signifieantly in low concentration (p<0.05). The ratio of visceral adipose weight to body weight decreased significantly in the medium concentration group (p<0.05). Among three acetic acid concentration groups, the medium concentration group showed lowest plasma and liver TG, TC levels and the ratio of visceral adipose weight to body weight.2) SD Rats were fed on a AIN-93G diet (C group), a modeling diet (M group, lipid content was 8.5% and was composed of 60.4 % soybean oil and 39.6 % lard), a AIN-93G diet with 0.2 % acetic acid (CA group) and a modeling diet with 0.2 % acetic acid (MA group) for ten weeks. Compared with the C group, the M group showed significant decrease in plasma high density lipoprotein cholesterol (HDL-C) but significant increases in plasma low density lipoprotein cholesterol (LDL-C), nonesterified fatty acid (NEFA) and insulin levels (p<0.05). Preheparin plasma lipoprotein lipase (LPL) activity in the M group decreased significantly (p<0.05). Liver TG, TC contents and hepatic total lipase activity in the M diet group increased significantly (p<0.05). Compared with the M group, the MA group showed significant increases in plasma HDL-C and apolipoprotein AI (APO AI) levels but significant decreases in plasma LDL-C, apolipoprotein B100 and insulin levels (p<0.05). Hepatic total lipase activity decreased signifieantly in the MA group (p<0.05). Prehepatin plasma LPL activity increased signifieantly in this group (p<0.05). Compared with the C group, plasma APO AI level increased significantly (p<0.05).3) SD rats were fed on a AIN-93G diet (C Group), a high fructose diet (60 % fructose) (F group), high fructose diets with 0.2 % acetic acid (FA group), 0.68 % vinegar powder (FP group) or 02 % acetic acid + 0.68 % vinegar powder (FAP group) for 8 weeks. Compared with the C group, the F group showed significant increases in fasting plasma TG, TC, HDL-C, LDL-C, glucose, insulin levels and serum uric acid level (p<0.05). Liver TG, TC, NEFA contents also increased signifieantly in the F group (p<0.05). Homeostatic model assessment of insulin resistance index (HOMA-IRI) and area under blood glucose curve (AUC) in oral glucose tolerance test (OGTT) increased signifieantly in the F group (p<0.05). Compared with the F group, the FA group and FAP group showed significant decrease in plasma TG, LDL-C and insulin levels, serum uric acid level and liver TG, TC and NEFA contents (p<0.05). AUC, HOMA-IRI and plasma HDL-C level in the FA group decreased signifieantly, also (p<0.05). The FP group showed significant decreases in liver TG and NEFA contents (p<0.05).4) Compared with the C group, the F group showed significant decreases in liver glycogen contents, hepatic pyruvate kinase (PK), Catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities but significant increases in hepatic glucose-6-phorsphatase (G-6-Pase), glucose-6-phorsphate dehydrogenase (G-6-PDHase) activities and malondialdehyde (MDA) contents (p<0.05). The percentage of saturated fatty acid (SFA) in total fatty acid (TFA) of liver significantly increased in the F group (p<0.05), while the percentage of polyunsaturated fatty acid (PUFA) decreased significantly (p<0.05). Additionally, the F group showed significant increases in the percentages of C18:0, C18:l, C20:4 n-6 fatty acids but significant decreases in the percentage of C18:2 n-6, C18:3 n-3, C20:5 n-3, C20:l, C20:2 fatty acids in TFA of liver (p<0.05). Compared with the F group, liver glycogen contents increase signifieantly in both FA group and FAP group (p<0.05). Hepatic PK activities increased in the FA, FP and FAP groups (p<0.05). Hepatic G-6-Pase activities decreased significantly in both FA group and FAP group (p<0.05). G-6-PDHase activity decreased in the FA group significantly (p<0.05). Hepatic CAT activity increased significantly in the FA group (p<0.05). Hepatic GSH-Px activity increased significantly in the FAP group (p<0.05). The SFA percentage of in liver TFA decreased significantly in the FAPgroup (p<0.05), while the percentage of PUFA increased signifieantly in FA group (p<0.05). The C18:1 percentages in liver TFA decreased significantly in the FA group and FAP group (p<0.05). The C18:2 n-6 percentages increased significantly in the FA, FP and FAP groups (p<0.05). Additionally, The percentages of C15:0, C17:l and C22:1 fatty acids increased significantly in the FAP group (p<0.05).5) Young healthy subjects were asked to ingest five rice vinegar powder tablets (containing 2.5 g rice vinegar powder) daily for 16 weeks. Compared with the control group (without vinegar powder tablets intake), serum total protein, albumin, and uric acid levels increased significantly in the vinegar powder group. However, all hepatic and renal parameters fluctuated within normal physiological range. The changes in serum total protein, albumin and uric acid were also within the clinically normal ranges and were not clinically relevant.Dietary acetic acid supplement showed significant anti-hyperlipidemia effect. The concentration of 0.2 % showed the best effect. Dietary acetic acid improved insulin sensitivity due to affecting TG metabolism in liver by increasing the activity of hepatic total lipase. Both acetic acid and the total nonvolatile components in vinegar could interfere with the development of insulin resistance induced by high fructose diet due to decreasing TG synthesis and NEFA content in liver, increasing C18:1 but decreasing C 18:2 n-6 fatty acid percentage in liver TEA. However, acetic acid could also exert its effect by abbreviation hepatic oxidative stress and inhibition hepatic glyconeogenesis. Daily intake of 2.5 g rice vinegar powder was safe to healthy people. For its increase effect on serum uric acid level, rice vinegar powder should be cautious for patients with hyperuricemia.
|
PDF Full Text Request