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IGF-1 & Cancer
IGF-1 & Cancer
25 Dec 2020
Disclaimer
IGF-1 (Insulin-like Growth Factor 1) is a growth hormone in our body. High IGF-1 levels are associated with increased risk of cancer. Increased IGF-1 levels are also suspected to underlie early puberty and autoimmune conditions.

What is IGF-1? How does it promote cancer growth? What may we do about it? A simple explanation in plain English by Dr Greger from the article How Do Plant-Based Diets Fight Cancer? (2013):

Every day, 50 billion of our cells die, and every day, 50 billion new ones are born. There’s a balance. Otherwise your body would shrink or get too crowded. Sometimes we need grow, like when we’re a baby or for that growth spurt around puberty. Our cells don’t get larger when we grow up; they increase in number. A child’s hand may only be made up of about 50 billion cells and may have to add half trillion or so while growing up.

Once we’re all grown up, though, we don’t want a lot of extra cells hanging around. We still need our cells to grow and divide, but out with the old and in with the new. We don’t want to be making more cells than we’re putting out to pasture. When you’re a kid, extra growth can be good; when you’re an adult, extra growth can mean a tumor.

How do our cells know when to tip the scale in favor of more dividing with less dying and when to come back into balance? A key signal is IGF-1, a growth hormone called insulin-like growth factor number one. IGF-1 levels go up when you’re a kid so you grow and then come back down when you’re done growing. Should your levels stay a bit too high as an adult, though, there’s a constant message sent to your cells to grow, grow, grow, divide, don’t die, keep going, keep growing. Not surprisingly, the more IGF-1 we have in our bloodstream, the higher our risk for many types of cancer.

When you’re a kid, growth is good, but too much growth when we’re all grown up can mean cancer. In my 90-second video, Cancer-Proofing Mutation, I describe Laron Syndrome, a type of dwarfism caused by congenital IGF-1 deficiency. Those affected don’t have that IGF-1 spurt in childhood so they grow up short-statured, but not having an excess of IGF-1 in their systems as an adult makes them nearly cancer-proof. This raises the question of whether one can achieve the best of both worlds by ensuring adequate IGF-1 levels during childhood and then suppressing excess growth promotion in adulthood. This can be done with a plant-based diet as I described in my last blog posts Cancer-Proofing Your Body and Treating an Enlarged Prostate With Diet, as well as in my 4-min video The Answer to the Pritikin Puzzle.

Thus animal protein seems to send a signal to an adult's body: "grow, grow, grow!" This may lead to unwanted growth like cancerous tumors. Plant proteins don't seem to cause such growth. Details in a 15-part video series by Dr Greger below.
15-Part Video Series (2012)

Articles by Dr Greger:

15-Part video series by Dr Greger:

(2012) Engineering a Cure

(1 mins) Transcript. Dr Greger's summary: "Lifestyle medicine pioneer Nathan Pritikin, who reversed his own heart disease through diet and went on to help millions of others, wasn't a doctor or dietician, but an engineer."

(2012) Ex Vivo Cancer Proliferation Bioassay

(3 mins) Transcript. Dr Greger's summary: "Two weeks on a plant-based diet appears to significantly enhance cancer defenses against breast cancer and colon cancer cells. The blood of those eating a vegan diet for a year suppresses cancer cell growth nearly eight times better."

(2012) Is It the Diet, the Exercise, or Both?

(4 mins) Transcript. Dr Greger's summary: "Whose blood is better at killing cancer cells? People who eat a standard diet and exercise strenuously, or those who eat a plant-based diet and just exercise moderately?"

(2012) Some Prostates Are Larger Than Others

(3 mins) Transcript. Dr Greger's summary: "Benign prostatic hyperplasia, or BPH — an enlarged prostate gland — affects 80% of older men, but like many other Western chronic diseases, it appears to be a consequence of our diet."

Excerpt:

It's so common in the Western world that most doctors just assume it's just an inevitable consequence of aging. But let's look around the world. In China, a medical college in Beijing reported that there was not 80% of the population affected, but about 80 cases, period. 84 cases over a 15-year timespan. It used to be considered a rare occurrence in China, but the incidence of both BPH and prostate cancer started "rising quickly", and now, the incidence of prostate enlargement in China is similar to that in developed countries.

Why? Well, the researchers suggest it's for the same reason for their skyrocketing cancer rates — a shift from their more traditional plant-based diet to one with more animal fat and animal protein. So, BPH may be like heart disease — a natural occurrence not of aging, but of eating an unhealthy diet. It may only be standard to get an enlarged prostate and die of a heart attack for those eating the Standard American Diet.

(2012) Prostate vs Plants

(3 mins) Transcript. Dr Greger's summary: "All men should consider eating a prostate-healthy diet, which includes legumes (beans, peas, lentils, soy); certain vegetables (like garlic and onions); certain seeds (flax seeds); and the avoidance of refined grains, eggs, and poultry."

This video summarizes factors believed to prevent or promote BPH, based on observational studies.

(2012) Prostate vs a Plant-Based Diet

(1 mins) Transcript. Dr Greger's summary: "Eating a plant-based diet may protect against BPH (benign prostatic hypertrophy, an enlarged prostate)."

Companion article:

(2013) Cancer-Proofing Your Body by Dr Greger.

(2012) IGF-1 as One-Stop Cancer Shop

(3 mins) Transcript. Dr Greger's summary: "Insulin-like growth factor (IGF-1) is a natural human growth hormone instrumental in normal growth during childhood, but in adulthood can promote abnormal growth — the proliferation, spread (metastasis), and invasion of cancer."

(2012) Cancer-Proofing Mutation

(1 min) Transcript. Dr Greger's summary: "Congenital IGF-1 deficiency can lead to Laron Syndrome (a type of dwarfism); but with such low growth hormone levels, those with the condition have dramatically lower cancer rates. This raises the question of whether one can achieve the best of both worlds — by ensuring adequate IGF-1 levels during childhood, while then suppressing excess growth promotion in adulthood."

(2012) The Answer to the Pritikin Puzzle

(4 mins) Transcript. Dr Greger's summary: "Lower cancer rates among those eating a plant-based diet may be a result of reduced blood levels of IGF-1, and enhanced production of IGF-1 binding protein."

(2012) How Plant-Based to Lower IGF-1?

(3 mins) Transcript. Dr Greger's summary: "Those eating vegan had significantly lower IGF-1 levels and higher IGF-binding proteins than those just eating vegetarian, suggesting that the more plant-based one's diet becomes, the lower one's risk of fueling growth hormone-dependent cancer growth."

(2012) Protein Intake & IGF-1 Production

(2 mins) Transcript. Dr Greger's summary: "Animal protein consumption triggers the release of the cancer-promoting growth hormone IGF-1."

(2012) Higher Quality May Mean Higher Risk

(3 mins) Transcript. Dr Greger's summary: "The reason animal proteins trigger the release of the cancer-promoting growth hormone IGF-1 more than plant proteins may be because the relative ratios of amino acids in animal proteins more closely resembles our own."

(2012) Animalistic Plant Proteins

(2 mins) Transcript. Dr Greger's summary: "While animal proteins increase levels of the cancer-promoting growth hormone IGF-1, and most plant proteins bring levels down, 'high quality' plant proteins, such as soy, may not significantly affect levels in either direction. This, however, may depend on the quantity consumed."

(2012) Too Much Soy May Neutralize Benefits

(3 mins) Transcript. Dr Greger's summary: "Vegans consuming 7 to 18 servings of soy foods a day may end up with circulating IGF-1 levels comparable to those who eat meat."

Companion article: How Much Soy Is Too Much? (2013).

(2013) How Much Soy Is Too Much?

(2 mins) How Much Soy Is Too Much? (Oct 2012). Dr Greger's summary: "To maintain the low IGF-1 levels associated with a plant-based diet, one should probably eat no more than 3-5 servings of soy foods a day."

Dr Greger says,

Soy is an excellent choice, but we should probably stick to no more than 3-5 servings a day."

Additional Articles & Videos by Dr Greger

Articles by Dr Greger:

Videos by Dr Greger:

(2019) Dairy & Cancer

(8 mins) Transcript. Excerpt:

They suggest it’s the animal protein, boosting the levels of a cancer-promoting growth hormone called IGF-1: insulin-like growth factor 1. If you look at 28 studies involving nearly 28,000 people—this is what’s called an albatross plot. Any study to the right of this line shows a link between IGF-1 levels and dairy products, milk specifically, or dairy protein consumption. And, any study hitting this line or over shows a significant association with higher IGF-1 levels.

(2016) Animal Protein Compared to Cigarette Smoking

(8 mins) Transcript. Dr Greger's summary: "Only about 1 in 10,000 people live to be 100 years old. What’s their secret?"

(2010) Dairy Hormonal Interference

(2 mins) Transcript. A short video that explains the relationship between dairy, IGF-1 and cancer.

(55 mins, 2012) Uprooting the Leading Causes of Death

About 12 mins of this presentation focuses on IGF-1 and cancer. Watch from offset 10:10 to offset 23:38.

IGF-1 & Early Puberty?

An excerpt from Why Are Children Starting Puberty Earlier? (2013) by Dr Greger:

The most consistent link between diet and premature puberty has been found to be animal protein consumption. Every gram of daily animal protein intake—that’s just like the weight of a paperclip—has been associated with a 17% increase in the risk of girls starting their periods earlier than age 12.

Why this link between animal protein and premature puberty? We know meat increases the level of IGF-1 and that alone is associated with early onset puberty.

IGF-1 & Autoimmune Conditions?

An excerpt from Plant-Based Diets for Multiple Sclerosis (2013) by Dr Greger:

Turns out this process of ridding our bodies of self-recognizing immune cells happens throughout our lives, mostly in our bone marrow. If you remember, though, in my video series on IGF-1 (starting with "The Answer to the Pritikin Puzzle" video) animal protein consumption increases the level of a cancer-promoting growth hormone that prevents apoptosis, prevents our body’s killing of cells it wants to get rid—that’s why IGF-1 levels are linked to cancer. So IGF-1 might contribute to the inappropriate survival of self-reactive white blood cells in autoimmune or inflammatory conditions. Maybe that’s why people who eat plant-based diets appear protected from autoimmune diseases, explaining, for example, the extraordinary rarity of most autoimmune diseases among sub-Saharan rural blacks following a traditional plant-based diet. Before they changed their diets, evidently not a single case of MS had been diagnosed among a population of 15 million.

Increased IGF-1 Due To Soy?

Are there plant foods that increase IGF-1 levels? Yes! Soy foods! Dr Greger has an article on this theme: (2013) How Much Soy Is Too Much? In one of his videos, he explains:

"To maintain the low IGF-1 levels associated with a plant-based diet, one should probably eat no more than 3-5 servings of soy foods a day."

Other doctors have lower limits on soy intake (1-2 servings only); see How Much Soy Daily?

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