Therapeutic effects of different doses of prebiotic (isolated from Saccharomyces cerevisiae) in comparison to n-3 supplement on glycemic control, lipid profiles and immunological response in diabetic rats

Abstract

Background: The regular intake of fber generates numerous health benefts. However, the efcacy depends on the duration of consumption and the ingested dose. Studies investigating the optimal dose are of interest to enable the inclusion of fber in the routine treatment of diabetic patients. Objective: We aimed to evaluate the efects of diferent doses of β-glucan (BG—isolated from Saccharomyces cerevisiae), in comparison to n-3 supplement, on the infammatory and metabolic parameters of Wistar rats induced to diabetes by streptozotocin. Methods: Forty animals were randomly divided into six groups receiving 0 mg/kg, 10 mg/kg, 20 mg/kg, or 40 mg/kg BG daily for 4 weeks or fsh oil derivative [1000 mg/kg of omega-3 fatty acids (n-3)] for the same period. One additional group was composed of healthy controls. Serum metabolic and immunological parameters were evaluated by colorimetric and ELISA assays respectively. Histopathological analysis of the liver, small intestine and pancreas were also conducted. Signifcant changes due to BG intake were set into regression models with second-degree ft in order to estimate the optimal BG dose to achieve health benefts. Results: The animals that ingested BG had lower food and water intake (p<0.05) than the negative control group (0 mg/kg). However, consumption was still elevated in comparison to healthy controls. Blood glucose and serum levels of total cholesterol, LDL-c, and TG (p<0.05) reduced in comparison to diabetic animals without treatment (better or similar to n-3 group depending on dose), but did not reach normal levels (in comparison to healthy controls). HDL-c was not diferent (p>0.05) among all groups. These reductions were already seen with the lowest dose of 10 mg/kg. On average, the serum levels of the hepatic enzymes ALT and AST were 40% and 60% lower in the BG groups in comparison to diabetic animals without treatment (better results than n-3 group). The group receiving 40 mg/kg reached similar values of healthy controls for ALT; whereas the same result occurred from the dose of 10 mg/kg for AST. The ideal dose, estimated from the mean of all metabolic parameters was approximately 30 mg/kg/day. Regarding the immunological profle, TNF-α signifcantly decreased in the BG groups compared to controls (p<0.05), reaching better values than n-3 group and similar to healthy controls. No signifcant diferences were found between the groups in IL-1β or IL-10 (p>0.05). No histological changes were found in the pancreas, liver, or intestine due to treatment among diabetic animals. Conclusions: BG signifcantly reduced blood glucose as well as serum total cholesterol, LDL-c and TG. There was a hepatoprotective efect due to the reduction in ALT and AST and a reduction in TNF-α, indicating a modulation of the immune response. In general, BG efects were better than n-3 supplement (or at least comparable) depending on the dose.