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Irisin is an anti-obesity and anti-diabetes hormone that regulates fat tissue and blood sugar.
In this post, we will discuss the benefits of irisin, genetic predispositions that may make you produce less irisin, and how to increase it.
Basics
Preptin, adropin and irisin are three co-workers in the regulation of energy homeostasis.
Irisin was discovered in animals and then later on in humans in 2012.
Since irisin works on muscles and fat, it is a myokine and an adipokine.
Myokines are a type of cytokines that have autocrine, paracrine and endocrine effects, mostly secreted by skeletal muscle.
Irisin is generated by exercise and acts as an insulin-sensitizing hormone.
Irisin is so powerful that even moderately increased levels of circulating irisin potently increases energy expenditure, reduces body weight and improves diet-induced insulin resistance.
It also plays a role in reproductive function.
Benefits
1. Balances Blood Sugar And Fights Diabetes
Irisin improves blood sugar regulation.
It increases glucose tolerance and reduces insulin resistance.
Irisin signals via AMP-activated kinase (AMPK) pathway to mediate glucose uptake and fatty acid oxidation.
It also lowers hemoglobin A1c.
Irisin may also play an important role in the regulation of maternal–fetal glucose homeostasis.
Low levels of irisin is associated with impaired carbohydrate metabolism in infants.
In animal models with Type 1 Diabetes, irisin helped repair cells.
2. Improves Weight Loss
Irisin improves weight loss by inducing PGC1α.
PGC1α is induced in muscle by exercise and stimulates many of the best known beneficial effects of exercise in muscle: mitochondrial biogenesis, angiogenesis and fiber-type switching.
PGC1α induces FNDC5.
FNDC5is the precursor of irisin.
FNDC5 promotes the conversion of white fat to brown fat (thermogenesis via PPARα).
FNDC5 influneces UCP1, which also contributes to the browning of white fat.
Brown fat has more mitochondria than white fat, so it is able to burn faster and give you more energy.
Irisin can also decrease food intake.
When rats were injected with irisin into the hypotalamus, they ate less.
3. Supports The Skeletal System
In mice, irisin released from skeletal muscle during exercise acts directly on bone by increasing cortical bone mineral density, bone perimeter and polar moment of inertia.
It may promote bone formation so that bones can better adaptto the increased load during persistent exercise.
It can do it without browning response of adipose tissue when given at a lower dose.
It may help with osteoperosis.
It also provides resistance to muscular dystrophy and denervation-linked muscular atrophy.
Irisin has also been shown to be positively correlated with bone mineral density in adolescent women.
4. Is Anti-Aging
Irisin legnthens telomeres.
Telomere shortening is a genetic marker of aging.
Irisin also decreases with age.
Increasing irisin may therefore decrease aging.
5. Has Anti-Cancer Effects
Irisin expression may help hepatic cancer.
It has also shown to protect normal cells and create apoptosis (cell death by 22-fold) in cancer cells.
Irisin levels are lower in hepatic and breast cancers, suggesting a possible protective role.
6. Protects The Heart, Brain and Vascular System
A mouse study showed that irisin might have a preventive role in atherosclerosis.
Administration of irisin protected against endothelial injury and ameliorated atherosclerosis by inhibition of oxidative stress.
Also, irisin decreased the plaque area and the infiltrating macrophages and T lymphocytes in the plaques, and down-regulated the mRNA expression of inflammatory cytokines in the aortas.
Higher irisin levels may contribute lower total cholesterol in both men and women.
It also decreases the oxidative stress from LDL cholesterol.
In rats with hypertension, irisin was able to lower blood pressure by increasing nitric oxide (via AMPK-Akt-eNOS- NO Pathway).
HDAC4 overexpression can induce cell death, increase lactate leakage, and mitochondrial dysfunction.
Irisin is able to significantly attenuate all of these effects and help with reoxygenation, making it beneficial for stroke, heart attack, and other hypoxic events.
Thus, irisin may be the reason why we don't suffocate in anaerobic exercise.
7. Is An Anti-Inflammatory And Anti-Oxidant
Irisin can attenuate inflammation of macrophages (shifting them towards a M2 state).
It can also reduce levels of IL-6, TNF-alpha, MIP-1α, and MIP-1β.
Irisin can prevent oxidative stress in the liver (through the inhibition of protein arginine methyltransferase-3).
Since irisin works on UCP1, it can decrease reactive oxygen species (ROS).
8. Is An Anti-Depressant
In an animal study, irisin was able to ameliorate depressive-like behaviors by regulating energy metabolism.
9. Increases Brain Function And Motivation
Irisin increases cognitive function.
In animals, FNDC5 inhibition reduces neurogenesis, while overexpression stimulates neural differentiation.
It can also increase brain derived neurotrophic factor (BDNF).
By working on BDNF, irisin may also work on the dopaminergic system, enhancing the motivation/reward system.
Irisin also works on GABA and the GABAergic system.
Dysfunction of the GABAergic system may contribute to cognitive impairment in humans.
Specifically, individuals with Alzheimer’s Disease have decreased cerebral GABA in the brain and CSF50.
Furthermore, GABA levels in human CSF decrease with aging, which has been associated with cognitive impairment.
The expression of irisin in the GABAergic brain cells might, to some extent, explain its effects on the central nervous system-mediated functions.
Irisin upregulates PGC-1α.
PGC1α deficient mice show a significant brain deficiency.
PGC-1α is usually under-expressed in Parkinson’s Disease and Lewy body disease patients.
PGC-1α by dietary treatment might benefit cognitive function and synaptic plasticity in Alzheimer’s disease by preventing Aβ production in the brain.
Testing and Levels
Low Irisin Levels Can Predict:
- Atherosclerosis and Behçet’s Disease
- Breast Cancer
- Chronic Kidney Disease
- Cholesterol Levels (inversely correlated)
- Coronary Artery Disease
- Fatty Liver Diseases - Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis
- Hyperglycemia
- Major Adverse Cardiac Events (such as Heart Attack)
- Metabolic Syndrome
- Sleep Apnea
- Type 2 Diabetes
High Irisin Levels Can Predict:
- Acute Appendicitis (with high neutorphil count)
- Hypothyroidism
- Liver Cancer
- Obesity and Morbid Obesity (probably signaling irisin resistance)
- Polycystic ovary syndrome
- Pregnancy (increases throughout pregnancy)
Higher levels may indicate "irisin resistance".
Irisin is generally higher in the summer/winter, but lower in the fall/spring.
In one study, irisin levels were 3.6 ng/mL in sedentary individuals and increased to 4.3 ng/mL in individuals undergoing aerobic exercise.
During pregnancy, IL1β, IL-5, IL-7, and IP-10 can predict irisin levels.
Irisin is higher in women than men (and similarly girls vs boys).
Estrogens play a role in irisin levels, so it is a good idea to get that checked.
How To Increase Irisin
What Increases Irisin?
- High fat diet
- Exercise (resistance training and HIIT induce the most irisin)
- Extreme Temperatures (Shivering and Sauna)
- Hormones like Leptin and Growth Hormone
- Supplements like CoQ10 and Holy Basil
- Drugs like Metformin
- Devices like Whole-Body Vibration
See more how to do these below.
1. Diet
A high fat diet increases browning of tissue (by upregulation of UCP1).
2. Exercise
Irisin is dependent on muscle contraction and intensity of an exercise.
So the more intense the exercise, the more irisin you'll produce.
It is important to note that chronic exercise does not increase irisin levels well, but single bouts of exercise increase it significantly. So, this may explain why extensive marathon training may be detrimental to health.
Also, it is important to know that the more fat you have, the higher your irisin levels can get after exercise.
Irisin is also dependent of muscle mass.
Exercise increases irisin more in lean women than lean men.
From order of greatest irisin release to least:
- Resistance Exercise (High Intensity Strength Training, increases irisin more than endurance training)
- Endurance training (Increases irisin levels 2x more than aerobic exercise)
- HIIT (High Intensity Interval Training, irisin levels increase after 6 hours for 13 hours.)
- Acute aerobic exercise
- Swimming (shown in rats)
- Low Intensity Exercise
3. Cold and Heat Thermogenesis
- Cold vests, hats, etc
- Ice plunges
- Sauna
- Shivering
- Sweating
4. Hormones
- Deficiency in Estrogen
- Growth Hormone
- Leptin
- Myostatin Inhibition
5. Supplements
- CoQ10 (enhances UCP1 uncoupling to increase brown fat)
- Holy Basil (increased IGF1 and irisin if combined with resistance training)
6. Drugs
7. Devices
Other
- FoXO1 activation
- Going Into Labor
- Recombinant GST-Irisin (in vitro)
What Decreases Irisin?
- AMPK inhibition (feedback)
- Caloric Restriction (short term - in subcutaneous fat)
- Chronic Bad Sleep
- Fasting
- Insulin (decreased irisin in plasma, but increased irisin in hypothalamus)
- Myostatin
- ROCK1 activation (inhibits UCP1 and PGC1a, reducing browning of fat)
- TGF-beta
Caveats
Obesity/insulin resistance may promote “irisin resistance”.
That would mean higher levels of circulating irisin would have less of an effect on fat tissue.
Taking the actions above would help with irisin resistance.
Mechanism Of Action
Irisin is comprised of 112 amino acids.
It is produced in muscles and fat tissue.
It is also synthesized in the brain (hypothalamus along with Neuropeptide Y), cerebrospinal fluid, heart muscle, along with peripheral tissues, including salivary glands, kidney and liver.
Exercise increases expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1alpha).
This causes the production of fibronectin type III domain-containing protein 5 (FNDC5), the precursor of irisin.
Irisin:
- Crosses the blood brain barrier
- Enhances expression of IL-15, Fndc5, VEGFβ, Lrg1 and TIMP4 (through PGC1alpha expression in vivo)
- Increases AMPK expression
- Increases ERK/MAPK pathway
- Increases PPARα
- Increases BDNF
- Increases NO production and phosphorylation of eNOS
- Independent of lactate levels
- Independent of Growth Hormone
- Independent of Leptin
- Decreases myostatin (myostatin impairs lipid and glucose metabolism)
- Decreases FABP4 (FABP4 increases adipose tissue)
- Decreases HbA1c
- Reduces ROS (via UCP1)
- Reduces IL-6, TNF-alpha, MIP-1α, and MIP-1β
- Reduces Orexin, Dopamine (DA) and Norepinephrine (NE) in the hypothalamus, but increases NE in plasma