The Surprising Truth About IGF-1 and How to Increase and Inhibit It

IGF-1 is commonly known to help build muscle or something to avoid when dealing with cancer. However, IGF-1 is also crucial in healing and tends to be low in those with chronic inflammation. There are some surprising things that you didn’t know about IGF-1 here. Read more…

What is Insulin-Like Growth Factor 1?

Insulin-Like Growth Factor 1 (IGF-1) is a hormone that is similar in structure to insulin and works with Growth Hormone to reproduce and regenerate cells.

Growth Hormone, made by the pituitary gland, stimulates the liver to produce IGF-1 and IGF-1 subsequently stimulates growth in cells throughout the body, leading to growth and development (as in the womb and through adolescence), strengthening of tissues (improving bone density, building muscle), and healing (skin, bones, gut lining, etc.), depending on what the body needs (R).

IGF-1 is so crucial to development that if it is not present in adequate amounts during the time when a child is developing, a short stature may result.

IGF-1, Overall Health, and Longevity

In several organisms such as fruit flies, worms, and rats, IGF-I is involved in the control of lifespan (R).

In most studies in mice, inhibiting Growth Hormone/IGF-I results in an increase in lifespan (up to 55%) (R).

However, in humans, the association between IGF-I levels and life expectancy doesn’t hold up (R).

Unlike lab animals, humans are exposed to various infections, stress, and other environmental factors that IGF-1 might help.

Several population-based studies describing a relationship between IGF-I and risk of dying were published with conflicting results. Two studies showed higher risk with higher IGF-I levels, while three showed higher risk with lower IGF-I levels. And in six studies there was no clear association at all (R).

Overall, however, having either low or high IGF-1 increases risk of dying from all causes (R).

In a meta-analysis of twelve studies done in 2011 with 14,906 participants, the risk of dying from all causes was increased in subjects with low as well as high IGF-1 levels (R).

People with low IGF-1 were at a 1.27X increased risk of dying from all causes, while those with higher levels were at a 1.18X increased risk (R).

I would say that when you look at all of the evidence, low IGF-1 levels are more likely to be a concern than high IGF-1 levels, but you still want to strike a balance (R).

The activity of IGF-I is influenced by at least six binding proteins (IGFBP). The most abundant is IGFBP-3, which binds more than 90% of IGF-1 in the circulation. Although IGF-I and IGFBP-3 are typically well correlated, there is speculative evidence that IGF-1 has an independent impact on disease risk, for example, on cancer (R).

When it comes to cancer, it’s probably better to err on having IGF-1 lower than higher (but not low).

When it comes to autoimmunity or chronic inflammation, it’s probably better to err on having IGF-1 higher than lower (but not high).

The Good


1) IGF-1 May Be Anti-aging


The length of telomeres in the DNA have shown to be important predictors of longevity. IGF-1 has been shown to correlate with greater telomere length in healthy subjects of all ages (R) and in elderly men, in another study (R).

In the famous Framingham Heart Study of 525 people between the ages of 72 and 92, greater levels of IGF-1 were associated with decreased risk of dying in the next 2 years (R).

IGF-1 helps prevent age-related cognitive decline by promoting new cell growth in the brain (in rats) (R).

Aging (R), and its associated frailties, such as lowered muscle strength, slower walking, and less mobility are associated with lower levels of IGF-1 in older women (R).

Critically ill patients tended to have lowered IGF-1 levels (R).

2) IGF-1 Increases Antioxidants

IGF-1 increases glutathione peroxidase, an important antioxidant enzyme (R).

It protects cells exposed to radiation, by preventing cell death and increasing the antioxidant status (R).

The negative to this is that if you have cancer and take chemotherapy, it may potentially protect cancer cells from dying as well.

3) IGF-1 Decreases Inflammation and Autoimmunity


When IGF-1 levels are low, inflammation tends to be high (R, R2).

In mouse models of autoimmunity and brain inflammation, administration of IGF-1 delayed disease onset; however, giving IGF-1 after the disease had developed led to enhanced worsening of the disease (R).

Allergic contact dermatitis, Multiple Sclerosis and type 1 diabetes is reduced in mice when they’re given IGF-1 (R).

Low IGF-1 levels have been documented in patients with HIV [R] and inflammatory bowel diseases (R).

Patients with chronic inflammatory diseases, such as Rheumatoid Arthritis and Lupus tend to have lower levels of circulating IGF-1 (R).

IGF-1 helps combat autoimmunity by increasing T Regulatory Cells (R).

IGF-1 also decreases MHCI gene expression (R).

In animals studies, high histamine levels in the body are associated with low IGF-1 in the blood (reduced via a histamine H1 receptor-mediated pathway) (R).

4) IGF-1 is Good for the Brain


IGF-1 improves learning and memory in animal models (R, R2).

It works as an anti-anxiety and anti-depressant in mouse studies (R).

Lower levels of IGF-1 are associated with depression in aged mice (R).

It speeds up mental processing in a study of 25 older men (R).

IGF-1 prevents the accumulation of amyloid plaque in the brain, in a rat model of Alzheimer’s disease (R).

In people, Alzheimer’s Disease and Dementia are associated with lower IGF-1 levels (RR2), and IGF-1 resistance accompanies insulin resistance in the brain in Alzheimer’s Disease (R),

It increases BDNF in the brain, mimicking the effects of exercise (R).

It helps motor neuron diseases like ALS (Amyotrophic Lateral Sclerosis) (R, R2).

ALS is associated with lower IGF-1 (R).

5) IGF-1 Creates Bigger Muscles and Reduces Muscle Wasting

IGF-1 is important for building muscle (R), and for reducing muscle loss in aging and disease (R).

6) IGF-1 Improves Blood Sugar Balance

Lower IGF-1 is associated with Metabolic syndrome (R).

IGF-1 infusions helped lower blood sugar, improve insulin sensitivity, and lower triglycerides in a study of Diabetes Type 2 patients (R).

People who are obese are more likely to have lower free IGF-1 (R).

In hepatitis C, people have lower IGF-1 and they are more likely to be insulin resistant, and it’s thought that these might be connected (R).

7) IGF-1 Protects against Heart Disease


IGF-1 has shown to have anti-inflammatory and anti-oxidant effects on blood vesselsstabilizing existing plaque and reducing additional plaque accumulation (R).

Cardiovascular disease (coronary artery disease, fatal ischemic heart disease, ischemic stroke, congestive heart failure, as well as slower recovery after a heart attack) is associated with reduced IGF-1 (R).

Lower IGF-1 levels were associated with higher risk of stroke in a study of a Chinese population (R).

8) IGF-1 Promotes Growth/Height

Growth Hormone’s (GH) activity in the body is dependent on IGF-1. So, IGF-1 deficiency causes insensitivity to GH and its effects on growth and repair.

IGF-1 helps restore height in children with IGF-deficiency (R).

Poor growth of an infant in the womb can be due to lowered IGF-1 (R).

Laron Syndrome (a type of dwarfism) is associated with lower IGF-1 in children (R).

9) IGF-1 Helps Bone Density

Higher IGF-1 levels are associated with greater bone mineral density in older women (R).

We know that IGF-1 is a direct promoter of bone growth (R).

However, IGF-1’s muscle-building (anabolic) effect may also promote bone density, since increasing muscle mass, in turn, requires greater bone strength (R).

10) IGF-1 Helps Your Gut


In animal models of colitis, burns and jaundice, treatment with IGF-1 improved gut health. It stimulated mucosal DNA and protein content and drastically reduced the incidence of bacterial translocation (R, R2, R3).

In animal models of small bowel transplantation, IGF-I improved the mucosal structure and absorptive function and reduced bacterial translocation (R).

Infants with gut permeability showed faster healing times when given IGF-1 (R).

12) IGF-1 Might Help Clear Bacterial Infections

In animal models, IGF-1 helps clear bacterial infections and improves survival in sepsis (R).

In animal models of cystic fibrosis, IGF-1 was able to help clear bacteria from the lungs (R).

13) IGF-1 Boosts The Immune System

IGF-1 can help increase natural killer cell activity (R).

IGF-I drives B-cells to multiply (R).

14) IGF-1 Helps With Electrolyte Balance

IGF-1 has been shown to help restore fluid balance in the elderly rats (R, R2) and in humans (R).

15) IGF-1 is Good For Skin

Reviving stagnant collagen synthesis can help protect skin against aging (R).

Insulin-like growth factor-I (IGF-I) is the most potent stimulator of collagen biosynthesis and may help prevent skin aging (R).


IGF-1 and growth hormone inhibit urea synthesis (R), which may cause lower blood urea nitrogen.  Growth Hormone-deficient children given human growth hormone results in lower urea nitrogen and this is due to decreased urea synthesis (R).

Advanced liver cirrhosis correlates with low IGF-1, in adults (R).

The Bad

Because IGF-1 stimulates growth, it can have negative effects on someone who is prone to cancer.

IGF-1 exerts powerful effects on each of the key stages of cancer development.

It increases cellular proliferation, angiogenesis, and metastasis and reduces cell death (apoptosis). It also can lead to resistance to chemotherapeutic agents (R).

When it comes to cancer, not only is IGF-1 important but so is IGF-1 binding protein (IGFBP), which blocks the effects of IGF-1.

So it’s the ‘free’ levels of IGF-1 that are most important.

1) IGF-1 May Contribute to Cancer Development

IGF-1 creates an environment conducive to breast cancer and resists anti-cancer drugs (RR2).

IGF-1 was shown to increase invasiveness of breast cancer (R).

A review of 17 studies found that IGF-1 is positively associated with breast cancer risk, taking levels of IGF binding protein (IGFBP3) into account, due to its effects on estrogen-sensitive tumors (R).

High IGF-1 is associated with an increased risk for prostate cancer (R).

Blood IGF-1 levels are higher in those with lung cancer than controls (R). (or maybe not (R).)

Higher IGF-1 levels in the blood are associated with colorectal cancer (R).

However, another study found that both low and high IGF-1 increased the chance of dying from cancer (R).

NOTE: Studies are unclear. Some take into account IGF-binding protein 3, and some do not. IGF-binding protein 3 (IGFBP3) is supposed to keep IGF-1 levels in the body in balance. When IGF binding protein (IGFBP) levels are low, free IGF-1 is unchecked and can cause growth that is out of control. That’s where cancer may come in. In most cases, elevated IGF-1 is associated with a reduced cancer risk more than an elevated risk (R).

2) IGF-1 Contributes to Acne

Increased IGF-1 may influence acne in adult men and women. While IGF-1 appears to have a stronger effect on acne in women, testosterone/androgens may play a greater role in acne for men (R).

Ways to Increase IGF-1

If you have low IGF-1 levels, you might want to focus a bit more on things that increase IGF-1, especially if you’re genetically predisposed to autoimmunity.

Ways to Inhibit IGF-1

If you have high IGF-1 levels, you might want to focus a bit more on things that inhibit IGF-1, especially if you’re genetically predisposed to cancer.

Genetic Influences/IGF-1 SNPs

SelfDecode is the best genetic analyzer and SNP decoder and will help you translate your raw 23andme data into meaningful information.

There are SNPs in the IGF1 gene:

  1. RS1019731
  2. RS2946834
  3. RS5742694
  4. RS6214
  5. RS6220
  6. RS7136446

There are SNPs in the IGF1R gene:

A hormone is only as good as the receptor that it binds to.

  1. RS2229765
  2. RS4966035

There are SNPs in the IGFBP3 gene (and IGFBP1):

IGFBP3 is the main binding protein to IGF-1.

  1. RS13223993
  2. RS2132570
  3. RS2453839
  4. RS2471551
  5. RS2854744
  6. RS2854746
  7. RS3110697

IGF-1 on SelfDecode

IGF-1 Ranges and Diseases:

Breast cancer:

  • Studies showed an IGF-1 range of 170-190 in women aged 45-60 with breast cancer (R).
  • In another study, premenopausal women with IGF-1 levels over 207 were at an increased risk of breast cancer (R).

Prostate cancer:

  • Studies showed an IGF-1 range of 160-170 for men with prostate cancer around age 60 (R).
  • In another study of men with prostate cancer averaging at age 65, IGF-1 levels were around 150-170 (R).
  • In the Physicians’ Health Study, an IGF-1 over 185 raised the risk for prostate cancer (R).

Cardiovascular Disease and Cancer:

  • Higher IGF-1 (approximately 190) is associated with increased risk of cardiovascular events and deaths from cancer in elderly men (average age 75) (R).

Higher Overall Risk of Disease or Mortality:

  • IGF-1 levels are about 70-80 or lower are associated with an overall increased risk of disease or death (R).


  1. Laura

    I received tests results back yesterday for my IGF-1. The NP at the endocrinologist office said my level was high(266) and suggested I may have a pituitary gland tumor. The “normal” range for IGF-1 seems to be different everywhere I look. I don’t know what to believe.

  2. Sandra Baker

    My mother died at age 68. Before she died the dr told her that she was a 68 yr old woman with a 100 yr old body. She was way underweight 79pds. She looked way older than she was. I have 6 sisters and all 7 of us have osteoporosis, and arthritis. Some of us have autoimmune diseases. 5 of us have it so bad we are disabled. What does this tell you of our IGF-1
    Thank you

  3. Sean

    So if im understanding this correctly if IGFBP3 levels are normal than high igf would not potentially increase cancer risk, correct?

  4. Simen

    This post contains some good points regarding IGF-1!

    And some bad ones:

    1. Why do you state that thyroid hormones inhibit IGF-1? Thyroid hormones stimulate growth hormone secretion and is permissive for IGF-1 production from the liver. Thyroid hormones also increase the amount of growth hormone receptors. Low IGF-1 is a classical finding in hypothyroidism due to the facts stated above. Hypothyroidism lead to short stature in children if not treated with thyroid hormones during puberty. Your study reference even clearly support these scientific facts, so why do do you disagree with your own reference?

    2. The reference regarding cortisol and IGF-1 is on Leptin, not cortisol.

    3. A lot of the minerals you list as stimulators of IGF-1 production does this by improving thyroid function. Selenium, magnesium and Zink all stimulate the conversion from T4 to T3, thus increasing hepatic IGF-1 secretion. Se point 1 on thyroid and IGF-1.

    4. Deer Antler and Colstrum is close to useless, if not 100% useless to increase systemic IGF-1. The oral bioavailibility of peptide hormones like IGF-1 is poor, and the amount of IGF-1 in those products is low. 110% waste of money/scam.

    4. You should read most of the scientific literature that you reference to back up your claims. By doing this, you avoid misleading people that are looking for knowledge. And as a bonus get a broader and more complex view on endocrinology.

  5. Juls

    How does IGF1 relate to testosterone?

    My 19 year old son was just tested and labs found:

    1. very low testosterone (total 149; should be 300-1200 / free 3.7; should be 5-21)
    2. very low IGF-1 (117) IGFBP3 and GH were not tested
    3. sub clinical hypothryroidism
    4. high DHEAs (469.9; should be 115.3-459.6)
    5. slightly elevated white blood count
    6. very low vit D (9.8; should be 32-80). We are now supplementing.

    Estradol, blood sugars, and cholesterol are all normal.

    We are trying to get in with an endocrinologist but it’s taking a while to get an appointment. He’s is really struggling to get school work done at college. He also sleeps a lot and has gained a lot of weight steadily for the past 5 years.

    Honestly I love the term “functionally illiterate” in the author’s description, it’s a good description of my son. Psych meds were tried when he was younger but never helped. He’s not been on any medication for the last three years. Now I’m thinking that his issues may have been endocrine related all along.

    Anyone have this combo of problems?

      • Good advice.But doubtful of the outcome. Why he is not advised for his Parathyroid hormone check ? Deficiency on the said gland may lead to Low IGF -1, Vit. D, and also low energy level too. I wish the little boy moves to a better life if his Parathyroid Hormone secretion is corrected. If it fails OR the MRI of brain as advised may be carried out simultaneously.

  6. Scott Long

    I think there needs to be more thought/research. My GH is on the low side 1,5 however my igf1 is almost 500. What does that make you think about the whole belief that gh controls igf1 ?

  7. Mark

    Fasting increases hgh which in turns increases igf-1 , also carbs effect insulin release which also has been proven to increase igf-1 signaling at the cellular level . Do more research on fasting an igf -1 an carbback loading an increase gh . Carbs do increase igf-1 its just all in timing .

  8. Jess

    I have high insulin levels but have not grown for three years (I am 14) I have low levels of the igf binding proteins. Why haven’t I grown if I have high insulin and what can I take to grow
    I also have polycrystic ovaries

      • Sebastian

        Be careful with colostrum. Before orthomolecular therapy my IGF was very low, after 2 months it was sky high. I took colostrum,high amino acids and various vitamins. I freaked out and even the doc was a bit worried. Somehow my somatotropic hormone went through the roof, still worried about that.

    • Carmelita

      PCOS, my daughter had that. We cut out all processed foods (everything was made from scratch) and started eating organic as much as possible. Many pesticides in our food create endocrine disruptors. Within 6 months the doctor said her blood levels are normal. Your endocrine system makes everything function. “The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things.” I was looking on this site and saw your statement. I know it’s not the answer about the levels but I do remember talking with people and bring told that pcos also can effect insulin. I wish you the very best.

  9. Robert Larabee

    I have Prostate cancer so it seems like I should work to lower my iGf-1 and increase IGF-3 – how would I increase the binding IgF-3

    Also- I have suffered with Fibro like illness for years – seems if I work to improve one condition I’ll likely make the other worse. My Dr. believes I have A sub clinical form of Sjogrens

  10. Santino

    What about mast cell activation disorder and igf-1?

    With MCAD multiple mutations of mast cells cause a lot if problems in multiple organs. I am intolerant to almost everything on earth except rice, chicken and beta carotene/vitamin a free free oil.

    My mast cells react to many natural ocurring substances with an strong allergic reaction if I take them as a supplement (no fillers used). For example with creatine, glutamine, N-Acetylcysteine, Methylcobalamine, curcumin, methylfolate, quercetine and many more. I can have a very limited amount of ascorbic acid and even more limited beta carotene.

    My bodies main mimiting reaction is a stron flu like response. Often I also suffered from extreme brainfog but that is better.

    Would igf-1 help with mast cell disorders? Or would it even make them worse?

    • Sam

      Logic would dictate that lowering IGF-1 would be beneficial in your case, as it upregulates autophagy of defective cells (which, as you point out, is a major problem for you.)

    • Maddy

      I would follow the authors suggestion and get your level tested. Have you read the website mastattack, she is a scientist with MCAD, I would ask her. Also, have you tried butyrate? It is helping my daughter slowly who has chronic daily migraine which arrived with food allergies (true IgE reactions) and also now has a plethora of food intolerances like you describe gluten, dairy, eggs, almost anything including veg with high histamine, and at one point all animal protein. It was awful. I feel your pain. She was completely vegan less high histamine ones like avacado and spinach. Butyrate can help heal the lining of the gut, promotes mucin cells to make mucous, and promotes Tregs which are important in promoting immune tolerance. More foods being tolerated. Good write up on this site, read it. Tolerating more foods now. I am add colostrum next to see if this helps gut further. But it definately has IGF-1 in it.

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