Insulin resistance (IR) can be defined as the decreased sensitivity of the body to sugar levels in the bloodstream. Normally, certain cells in the body remove sugars following a meal and convert them to glycogen, the storage form of sugar. The hormone insulin plays a key role in this process.
Some horses and ponies, like easy keepers or those that are overweight, become insensitive to the effects of insulin and therefore have abnormally high blood sugar levels.
“Persistently high blood sugar levels put otherwise healthy horses at risk for developing laminitis, a painful and life-threatening condition in which the hoof wall separates from the underlying coffin bone,” explains Kathleen Crandell, PhD, a nutritionist with Kentucky Equine Research.
Since the discovery of IR and the increased recognition of the importance of IR in equine metabolic syndrome, veterinarians and researchers have been seeking ways to improve the health and longevity of affected horses.
Recently, a group of researchers in Kentucky explored the use of an algae-derived omega-3 fatty acid, docosahexaenoic acid (DHA), in horses with IR, hypothesizing that DHA would be beneficial based on research previously conducted in rodents. The researchers fed horses either a control diet or the control diet supplemented with a DHA-rich microalgae meal (150 g/day) for 49 days. To simulate IR, they then administered dexamethasone (0.04 mg/kg/d) to the horses for 21 days. Researchers measured IR subsequently using a glucose tolerance test.
Key findings of the study were:
• Daily supplementation with the meal containing 14% DHA was associated with an increased plasma DHA concentration, and;
• Supplementation with the DHA-rich microalgae meal had no effect on baseline insulin or glucose concentrations; however, after insulin resistance was induced with dexamethasone, horses supplemented with DHA had lower baseline insulin (42.3% lower) and glucose (10.4% lower) concentrations.
“The researchers suggested the DHA-rich microalgae meal may have had an insulin-sensitizing effect, and there may be a potential therapeutic role for DHA-rich microalgae meal in the nutritional management of insulin resistance in horses,” Crandell summarizes.
Nonetheless, Crandell and the study authors both suggested that further research is needed to determine the effects of a DHA-rich microalgae meal on IR and to determine the mechanisms responsible for the effects of a DHA-rich microalgae meal on blood glucose and insulin concentrations.
*Brennan, K.M., D.E. Graugnard, M.L. Spry, et al. 2015. Effects of a docosahexaenoic acid–rich microalgae nutritional product on insulin sensitivity after prolonged dexamethasone treatment in healthy mature horses. American Journal of Veterinary Research. 76(10):889-896.
