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August 26, 2015
For some, irisin sounds like a mythological creature thought up by J.R.R. Tolkien, and until last week, that would not have been too far off. Irisin was first identified by Harvard Medical School’s Bruce Spiegelman in 2012 and has been a point of scientific strife ever since. While the idea of irisin, a supposed “exercise hormone” that fights obesity had aroused extensive interest, several related studies and papers claimed the results were based on flawed testing kits and that such a hormone was non-existent.
Spiegelman and his colleagues became determined to prove their tests were not flawed and the type I transmembrane protein FNDC5 is, in fact, enhanced in muscle during exercise in both mice and humans. Three years later, they have done just that. The most recent study, published in Cell Metabolism claims to have found human irisin in the blood at nanogram levels.
Researchers came to this conclusion by testing specimens from sedentary individuals and individuals who underwent 12 weeks of aerobic training. They found circulating blood irisin levels rose in blood samples from those involved with the aerobic training.
Now that Spiegelman and his team have put the naysayers to rest, there is much to be explored around how irisin affects our bodies when we exercise. We know it burns fat, but is it significant enough to pave the way for obesity drugs and help with associated risks of diabetes, heart disease, and cancer? It very well may, but for now, we rest assured knowing that our body is producing more irisin with every step, lunge, and jump.
Below are links to two articles that provide an in-depth look at the history of irisin and how this discovery could benefit our health.