Effects of diet induced short chain fatty acids on blood metabolites and key regulators of lipid metabolism in gilts

Abstract

Background: Dietary fiber has been shown to help improve several metabolic disorders including obesity and type II diabetes. However, the mechanism by which this occurs is poorly understood. Purpose: This study was designed to compare the effects of energy restriction and dietary fiber and subsequent production of short chain fatty acids on body composition, biomarkers of health, and hepatic and myocellular expression of key regulators of lipid metabolism Methods: Crossbred gilts (n=17) were randomly assigned to either a control (CON), high fiber (HF) or energy restricted (ER) diet for 42 days. Gilts on the CON and HF diets were fed ad libitum. The ER Gilts were pair fed HF gilts and matched for body weight gain. Blood samples were collected and glucose, insulin, triglycerides, non-esterified fatty acids and short chain fatty acids (SCFA) concentrations were measured. Liver and muscle tissue were biopsied and expression of peroxisome proliferator-activated receptor gama (PGC-1α) and carnitine palmitoyltransferase 1 (CPT1) were determined via RT-PCR. Results: HF gilts had significantly higher plasma TG and lower NEFA concentrations when compared to the CON and ER. The HF diet elicited a significant increase in all plasma SCFA concentrations. No differences in fold change of myocyte CPT1 and PGC-1α mRNA expression were found while they tended to be lower in hepatic samples of the HF gilts. HF gilts also had a lower (P < 0.05) back fat thickness when compared to the ER even though energy intakes were similar. Minimal changes were observed in fasting glucose and insulin as a result of diet. Conclusions: Gilts consuming a diet high in dietary fiber (DF) significantly altered their plasma lipid profiles independently to that of energy restriction and body weight and appears to be a result of plasma SCFA concentration. DF and/or SCFA appear to have minimal affects on CPT1 and PGC-1α in the liver and muscle of gilts.