Effects of High-Sugar and High-Starch Diets on Postprandial Inflammatory Protein Concentrations in Horses

Mature, nonpregnant, Thoroughbred mares were used to determine the influence of high-starch and high-sugar diets on postprandial inflammation. Plasma samples were obtained hourly from mares (n = 12) consuming one of two treatment diets, either a diet high starch and sugar (STR) or the control (CON) diet that was low in starch and sugar. Plasma was analyzed for concentrations of lipopolysaccharide (LPS) and the inflammatory cytokines interleukin (IL)-1β and IL-6. Hour 0 was included as a covariate in the statistical model, and where interactions between the covariate and other model variables existed, simple effect means were separated at three levels of the covariate: lower 95% confidence limit (CL), mean, and upper 95% CL. For horses with low (P = .016) and average (P = .065) initial LPS concentrations, LPS was greater or tended to be greater in STR compared with CON at hour 2 after feeding. No other differences were detected for LPS concentrations. For horses with low (P = .037), average (P = .006), and high (P = .001) initial IL-1β concentrations, plasma IL-1β was greater in STR than CON at hour 2 after feeding. For horses with high initial IL-1β concentrations, IL-1β also tended to be greater at hour 3 (P = .077). For horses with low (P = .022) or average (P = .063) initial IL-6 concentrations, IL-6 was greater or tended to be greater at hour 1 than 0. No effect of diet was detected for horses that started with high initial IL-6 concentrations. High-starch and high-sugar diets increase postprandial IL-1β concentrations, and it is likely that this effect is independent of LPS.