I was recently reading a study about the effectiveness of resveratrol + leucine to lower insulin numbers. In the study, 10 of 15 horses were positive responders. The others were non-responders. This newsletter shares some insights into the study.
◆︎ What is “Numbers Needed to Treat” (NNT)?
For basic understanding, numbers needed to treat is the number of people (or horses) that you would need to treat to get one responder.
We always like to think that when we take a drug or a supplement, it will have the intended result for us. But what we find is that many times, it isn’t as effective as we hope.
Let’s look at the use of aspirin in humans for migraines. In a study, the measured endpoints were that the person was (a) pain-free after two hours, or (b) had mild pain two hours later.
a) For the pain-free endpoint after two hours, the numbers needed to treat was 8.1. This means that 8 people would need to be treated for one person to be pain-free.
b) The numbers are also bleak for people who had pain relief (mild pain), with the numbers needed to treat of 4.9. This means that 5 people with migraines would need to take aspirin for one of them to have pain relief.
◆︎ Importance of endpoints:
To determine the numbers needed to treat, an endpoint must be defined. This could be key to determining if a treatment is effective. We can see from the information about aspirin, there is a huge difference with a change in endpoints.
◆︎ An example of endpoints in horses:
Let’s look at an example of endpoints in horses administered a common EPM medication, available by prescription-only. In a study of that drug, they considered clinical success as either:
» An improvement of at least one grade (on a 0-5 scale) of neurological symptoms OR
» Conversion to a negative antibody test
They found that 60-64% of the treated horses reached that goal.
◆︎ This is important because:
➡ The horse may have improved, but not enough for the owner to be satisfied. If the horse had severe symptoms, the horse would have needed to improve more that one grade of neurological symptoms.
➡ The horse may be one of the 40% that were non-responders.
➡ Although this drug is commonly prescribed, the horse owner’s expectations may not be met.
◆︎ Insulin levels after resveratrol + leucine
How this whole discussion relates to the study that I read regarding insulin levels and supplementation with resveratrol + leucine:
In that study, they measured the insulin curve after an oral sugar test. They orally administered about 2 large 60 cc syringes of Karo light corn syrup. They measured how high the blood insulin numbers rose over time.
They found that supplementing with resveratrol + leucine, blunted how high the insulin numbers rose, in the horses that were responders. 10 of 15 horses were responders.
◆︎ What are the important points to this?
➡Not all horses responded to the supplementation.
➡The baseline insulin numbers appeared to be about the same before supplementation and after supplementation.
➡The insulin levels didn’t go as high with the responders that were supplemented. BUT we rarely feed an insulin resistant horse that level of sugar. They did not do a study in which the horses were fed a low sugar/starch diet.
◆︎ Take home message:
With our best efforts, our horse may be one of the responders to a veterinary treatment, or to specific supplementation. But maybe not.
We do the best that we can for our horses. Understanding the limitations of treatment is a part of that.
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©Joan Kulifay 2025