The Athlete's Way

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Irisin: The “Exercise Hormone” has Powerful Health Benefits

Irisin can help maintain healthy weight, improve cognition, and slow aging.

If you need one more reason to motivate yourself to be more physically active, you can add the exercise induced hormone irisin to your list. In the past two years scientists have discovered that a hormone called irisin—which is released after moderate endurance aerobic activity—has the ability to help maintain healthy body weight, improve cognition, and slow the aging process.

In 2012, Bruce Spiegelman, PhD, a cell biologist at Dana-Farber Cancer Institute in Boston dubbed the hormone "irisin," after Iris, a Greek messenger goddess. Spiegelman foresaw the role of irisin as a ‘messenger’ saying, "There has been a feeling in the field that exercise 'talks to' various tissues in the body. But the question has been, how?" His ongoing research—along with that of others around the globe—continues to solve the irisin riddle.

At the time of irisin's initial discovery, Spiegelman believed that it was an important first step in understanding the biological mechanisms that translate physical exercise into beneficial changes throughout the body—both in healthy people and in preventing or treating disease. A variety of studies released since 2012 continue to show that the “exercise hormone” irisin (also known as FNDC5) has wide ranging health benefits.

Irisin Helps Maintain a Healthy Weight

Irisin was first reported by Bruce Spiegelman et al in the journal Nature in January 2012. Spiegelman and his colleagues at Dana-Farber isolated the hormone irisin which is released from muscle cells after endurance exercise and had a hunch that it was somehow linked to triggering many of the health benefits of exercise.

Spiegelman and colleagues believe that irisin is a highly promising candidate for development as a novel treatment for diabetes, obesity and perhaps other disorders, including cancer.

The researchers found that irisin is capable of reprograming the body's fat cells to burn energy instead of storing it. Experiments have shown that irisin levels increase as a result of regular aerobic exercise, but not during short-term bursts of anaerobic muscle activity.

Irisin increases metabolic rate and is thought to have potential anti-obesity effects. When irisin levels rise through aerobic exercise the hormone switches on genes that convert white fat into "good" brown fat. This is beneficial because brown fat continues to burn off more calories beyond just the energy used to do the actual aerobic exercise. This helps people maintain a healthy BMI, avoid obesity, and conditions such as type-2 diabetes.

Irisin Stimulates the Growth of Neurons and Improves Cognition

In October 2013 Spiegelman and his team identified that when irisin is released during endurance exercise it improves cognitive function and protects the brain against degeneration. In a breakthrough discovery, Dr. Bruce Spiegelman and colleagues at the Dana-Farber Cancer Institute and Harvard Medical School found that when irisin becomes elevated in the brain through endurance exercise it triggers neurogenesis (the growth of new neurons).

I wrote a Psychology Today blog post titled “Scientists Discover Why Exercise Makes You Smarter” based on these findings.

Irisin stimulates neurogenesis.
Spiegelman and colleagues found that raising levels of irisin increased the expression of BDNF (brain-derived neurotrophic factor) and activated genes involved in learning and memory. Aerobic exercise has been linked to increasing BDNF for over a decade, but this study was the first to identify the chain reaction that occurs to increase BDNF and stimulate neurogenesis.

Irisin May Slow the Aging Process

On February 17, 2014 scientists from Aston University in the UK published a study showing that irisin slowed the aging process by lengthening telomeres. The study titled “Plasma Irisin Levels Predict Telomere Length in Healthy Adults” was published in the journal Age.

Irisin lengthens telomeres (in red).
Telomeres are the protective caps on the ends of chromosomes that affect how quickly cells age. They are combinations of DNA and protein that help cells remain stable by protecting the ends of chromosomes. As telomeres become shorter, their structural integrity weakens, which causes cells to age and die younger.

In recent years, shorter telomeres have become associated with a broad range of aging-related diseases, including many forms of cancer, stroke, vascular dementia, cardiovascular disease, obesity, osteoporosis and diabetes.

The research team led by Dr. James Brown found a significant link exists between irisin levels in the blood and a biological marker of aging linked to telomere length. This is not the first study to link lifestyle choices to longer telomeres, but it is the first to hone in on irisin as the hormone driving the molecular benefits of exercise on telomere length.

A few months ago, I wrote a Psychology Today blog post titled “4 Lifestyle Choices That Will Keep You Young” based on a pilot study released in September of 2013 which showed that changes in: physical activity, diet, stress management, and social connectivity may result in longer telomeres.

Using a population of healthy, non-obese individuals, the team at Aston University found that individuals who had higher levels of irisin also had longer telomeres. The finding provides a potential molecular link between keeping active and healthy aging. People who have higher irisin levels were found to be "biologically younger" than those with lower levels of the hormone.

Dr. James Brown, from Aston's Research Center for Healthy Aging, concluded: "Exercise is known to have wide ranging benefits, from cardiovascular protection to weight loss. Recent research has suggested that exercise can protect people from both physical and mental decline with aging. Our latest findings now provide a potential molecular link between keeping active and a healthy aging process."

Conclusion: Pharmaceutical Derivatives of Irisin May Help Fight Disease

Spiegelman believes that his team's findings merely scratch the surface of multiple benefits of irisin. They are continuing to explore the hormone's possible benefits in metabolic diseases like diabetes, insulin resistance, and obesity, which constitute a growing epidemic around the world, as well as neurodegenerative illnesses like Parkinson's disease.

Spiegelman cautions that the discovery of irisin won't allow people to skip the gym and build muscles by taking irisin supplements, because the hormone doesn't appear to make muscles stronger. 

Spiegelman added that as growing evidence implicates obesity and physical inactivity in cancer development, it's conceivable irisin-based drugs may have value in prevention and treatment of the disease. The irisin discovery has been licensed by Dana-Farber exclusively to Ember Therapeutics for drug development.

Spiegelman said it should be possible to move an irisin-based drug rapidly into clinical testing. This is promising for people who are unable to make lifestyle choices that include regular physical activity. That said, these findings have the power to motivate anyone who is able to exercise to make aerobic activity a daily habit for a broad range of health reasons.

If you are in a position to make moderate endurance aerobic activity a part of your daily routine you can reap the benefits of irisin right here, right now—naturally—without having to pay the cost and potential side effects of taking a pill that is still in the earliest stages of development. 

If you'd like to read more on this topic, check out my Psychology Today blog posts:

Follow me on Twitter @ckbergland for updates on The Athlete’s Way blog posts.

Christopher Bergland is a world-class endurance athlete, coach, author, and political activist.

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