Impact of DHA Supplementation on Inflammation Reduction in Metabolic Horses - Research Reflection

By Juliet M. Getty, Ph.D.

Researchers from the University of Kentucky were looking for an effective way to reduce inflammation in horses suffering from equine metabolic syndrome (EMS), characterized as overweight and insulin resistant. EMS is generally treated with one of two pharmaceuticals – metformin or levothyroxine. However, there are questions about their efficacy and long-term usage. In humans, supplementation with the long-chain omega 3 fatty acid, docosahexaenoic acid (DHA) has been shown to improve insulin sensitivity, promote fat loss, and reduce inflammation. The purpose of this study was to determine if DHA supplementation would have the same beneficial impact on horses.

In a natural setting, pasture grasses provide the omega 3 fatty acid known as alpha linolenic acid (ALA). ALA is one of two essential fatty acids, meaning it cannot be produced and hence, must be in the diet. Within the horse’s tissues, ALA is converted to DHA, which has potent anti-inflammatory properties. However, the conversion rate is not efficient enough to offer significant potential for the horse already suffering from high levels of inflammation.[i] Consequently, the researchers chose to supplement DHA directly.

Fish oils are high in DHA and another omega 3 known as eicosapentaenoic acid (EPA). However, horses do not care for the taste of fish. Also, DHA has been shown to be more readily incorporated into tissues than EPA. Because of these factors, the researchers decided upon a DHA-rich microalgae for their study. Ten mixed-sex and mixed-breed horses with EMS were fed 16 grams of DHA per day for 46 days. Inflammatory status, glucose, and insulin were measured before and after the experiment.


The results showed a remarkable reduction in inflammatory markers. And interestingly, horses fed DHA-rich microalgae showed a lower insulin response to oral sugar administration than the control group experienced.

Implications for your horses

Insulin is highly inflammatory, and can be elevated with Cushing’s disease, metabolic syndrome, and stress. It can lead to increased fat storage and leptin resistance, creating a vicious cycle of overeating and obesity. Reducing insulin, and hence, inflammation, can do wonders for your horse with metabolic conditions. Omega 3 fatty acids can assist with this.

Adding ground flax seeds, chia seeds, and hemp seeds to the diet will offer the two fatty acids that are considered essential: ALA – an omega 3, and linoleic acid (LA) – an omega 6. And for most horses, these feedstuffs will meet their needs. (Keep in mind that hay has virtually no essential fatty acids left.) But in circumstances where a horse has high levels of inflammation, the addition of DHA is a better approach because it is far more effective at modulating insulin and inflammatory markers than ALA. Many DHA supplements come from fish oils. But because the fishy taste is difficult to overcome, supplementing microalgae instead, though still somewhat “marine-tasting,” is much better tolerated.[ii]

Though not specifically tested in this experiment, the researchers also commented on how high-DHA microalgae can improve glucose and insulin response after dexamethasone administration. This is a significant piece of information for horse owners who may be reluctant to used dexamethasone on a short-term basis for allergies or other minor disorders when the horse also has metabolic issues.

Bottom line… consider high-DHA microalgae supplementation to help your horse recover from insulin-related metabolic conditions.


[i] Kentucky Equine Research Staff, 2016. Proactive omega-3 supplementation for equine athletes.

[ii] For a high-DHA microalgae source, consider Algae to Omega (EquiForce), available at Dr. Getty’s Free Shipping Supplement Store. 


Elzinga, S.E., Betancourt, A., Stewart, J.C., Altman, M.H., et. al., 2019. Effects of docosahexaenoic acid-rich microalgae supplementation on metabolic and inflammatory parameters in horses with equine metabolic syndrome. Journal of Equine Veterinary Science, 83, 102811.


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