Fructokinase, Fructans, Intestinal Permeability, and Metabolic Syndrome: An Equine Connection?
Authors: Johnson Richard J, Rivard Chris, Lanaspa Miguel A, Otabachian-Smith Silvia, Ishimoto Takuji, Cicerchi Christina, Cheeke Peter R, Macintosh Bridgett, Hess Tanja
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Fructans—inulin-type polymers abundant in cool-season pasture grasses—cannot be directly digested by equine enzymes, but gram-positive caecal bacteria readily ferment them into free fructose via fructanase activity. Recent evidence in other species demonstrates that fructose metabolism by fructokinase C in hepatocytes generates reactive oxygen species and insulin resistance, whilst intestinal fructokinase may compromise the gut barrier and promote endotoxaemia. Johnson and colleagues propose a mechanistic link between pasture fructan consumption and equine metabolic disease, suggesting that bacterial conversion of fructans to fructose could trigger the cascade of intestinal permeability, systemic endotoxin translocation, and hepatic oxidative stress that precipitates laminitis in susceptible horses. Though still speculative, this hypothesis offers a compelling explanation for why certain grazing conditions and forage types predispose to acute laminitis episodes, particularly in insulin-resistant animals. The authors call for targeted research into equine fructanase activity, fructokinase expression in liver and intestinal tissue, and the specific contribution of dietary fructans to metabolic endotoxaemia and laminitis pathogenesis—investigations that could refine both preventive management strategies and therapeutic interventions in high-risk populations.
Read the full abstract on PubMed
Practical Takeaways
- •High fructan pastures (especially in spring and fall) may increase laminitis risk in susceptible horses through mechanisms involving intestinal bacteria-mediated fructose generation and hepatic metabolism
- •Managing fructan intake through grazing time restrictions, hay feeding, or pasture selection could be a preventive strategy for metabolic syndrome and laminitis-prone horses
- •Further research is needed to confirm these mechanisms before making definitive dietary recommendations, but reducing fructan exposure in horses with insulin resistance or laminitis history warrants consideration
Key Findings
- •Fructans in pasture grasses are converted to fructose by gram-positive bacteria in the equine gut
- •Fructose metabolism by fructokinase in liver and small intestine generates oxidative stress and increases intestinal permeability
- •Increased intestinal permeability from fructose may lead to endotoxemia and features of metabolic syndrome including insulin resistance
- •The authors hypothesize that fructanase activity and fructokinase-mediated fructose metabolism may be mechanistic pathways linking fructans to laminitis development in horses