Spirulina for Insulin Resistance?

First, I’m a huge fan of supplemental Spirulina platensis and have been for many years. There has been buzz this fall surrounding a study that supposedly shows Spirulina supplementation reversed Equine Metabolic Syndrome [EMS].

Spirulina platensis under the microscope.

The study by Nawrocka et al appeared in the August 2017 issue of the journal Marine Drugs. In the first part of the study the researchers quantified fatty acids, amino acids and other components in the Spirulina. They also confirmed its previously documented antioxidant benefits in cultured equine cells.

The second part of the study utilized three groups of horses – normal, EMS and EMS on a Spirulina supplemented diet.  After 3 months on the experimental diets 5 of 6 horses in the EMS + Spirulina group tested normal on a CGIT – combined glucose and insulin tolerance test. A popular equine lay magazine reporting on this study stated this indicates the horses were negative for EMS after 3 months but this is not accurate and also not what the study said.

The CGIT test is not reliable in horses.  It has poor sensitivity, which means there is the potential for many falsely negative/normal results.  It also has poor repeatability. Results from one test date can be very different from another in the same horse. The bottom line is that we can’t rely on those findings but it should be noted significant changes only occurred in the EMS horses supplemented with Spirulina.

Among the other changes noted after three months in the Spirulina group was weight loss. However, the horses were on a diet of 1.5% of the body weight in timothy hay which alone could explain the weight loss noted.  The EMS horses not given Spirulina did not have a weight loss but the article did not give details about the differences between the pelleted feeds the EMS horses in the two groups received. The EMS + Spirulina group also showed a reduction in the cresty neck score, but not to a normal level.

Four out of six of the EMS + Spirulina horses had a significant reduction in their insulin levels while the EMS group not on Spirulina did not. The insulin levels were still very abnormal, but lower. Again, it is unknown to what extent differences in the composition of the pelleted feeds given to the two EMS groups might have contributed.

Leptin, a marker of insulin resistance independent of insulin and glucose dynamics, was not changed by Spirulina supplementation.

The study did not give the actual dosage of Spirulina that was used, or whether the horses were monitored to see if they were actually consuming the whole dose. This is a significant point because Spirulina is not particularly palatable.  In my experience, when horses are presented with Spirulina pelleted into a palatable base and mixed into their usual meal 1/3 will refuse to eat it, 1/3 eat slowly and may not eat it all while another 1/3 will consume it readily.

This isn’t the first time Spirulina has been investigated in metabolic syndrome/insulin resistance. Benefits have been shown in humans and laboratory animals. However, there are significant differences in the syndrome between these species and the horse.

The take home message is there are many questions regarding this study. Even if the findings are reliable, it’s not a cure by any means.  Controlled calorie intake using a diet of low sugar + starch hays with small amounts of similarly low sugar + starch carrier feed for supplements, plus as much exercise as possible, remains the foundation of management of Equine Metabolic Syndrome.  For details based on over a decade of following thousands of these horses please visit http://www.ecirhorse.org.

Eleanor Kellon, VMD