Psyllium lowers blood glucose and insulin concentrations in horses

Abstract

The metabolic effect of feeding psyllium daily to horses is unknown. Eight 11- to 16-yr-old (Trial 1) and sixteen 7- to 16-yr-old (Trial 2; Trial 3) light breed stock horses were used in a completely randomized design to determine the effects of psyllium supplementation on BW, BCS, neck circumference, tailhead fat, plasma glucose, insulin, leptin, ghrelin, and adiponectin concentrations. An intravenous glucose challenge was also performed and the same variables were measured (Trial 3). Horses were stratified by sex and BW and put on trial for 42 d (Trial 1) and 60 d (Trial 2). Horses were individually fed a grain ration at 0.5% BW (Trial 1) and 0.25% BW (Trial 2), hay at 1.5% BW (Trial 1;Trial 2), and a psyllium treatment. Psyllium treatment levels for Trial 1 were: 1) 90 g/d psyllium or 2) an isocaloric control and 0 g/d psyllium. In Trial 2 levels of 180 and 270 g/d psyllium were added. Trial 3 took place the day after Trial 2 ended; horses were administered an intravenous dextrose solution at 0.5% BW after a 12 h fasting period. In Trial 1, horses fed psyllium had a greater (P = 0.01) increase in neck circumference than those not fed psyllium. Trial 2 revealed treatment by time interactions for glucose (P < 0.001) and insulin (P = 0.03). Glucose was lower 90 min (P = 0.05) and 120 min (P < 0.001) after a meal in horses fed psyllium compared to those not fed psyllium. Insulin concentrations were lower 90 min (P = 0.002) and 300 min (P < 0.001) in horses fed psyllium compared to those that were not. There was no difference in glucose (P = 0.48) or insulin (P = 0.15) concentrations between horses on 90, 180, or 270 g psyllium treatments. In Trial 3, horses fed psyllium had lower glucose (P = 0.03) and adiponectin (P = 0.02) concentrations than horses not fed psyllium. Supplementing horses with any level of psyllium appears to lower concentrations of plasma glucose and serum insulin after a meal.