This article takes a deep dive into the complex truth about the IGF-1 connection to cancer and heart disease.
The quick answer:
1) No, meat and animal protein does not necessarily “cause” cancer, and the truth is much more complex.
2) IGF-1 is a critically important hormone that can be good or bad depending on the context.
IGF-1: A Brief Summary
IGF-1 is one of our body’s most important anabolic hormones. Anabolic hormones are in charge of growth, and growth can be both good or bad depending on context.
Animal protein raises IGF-1 more than other foods, but this doesn’t mean meat is bad for you, or is “as bad as smoking cigarettes” as some headlines have proclaimed.
When IGF-1 levels are too high, some forms of cancer grow more easily (mainly prostate and breast). However, when IGF-1 levels are low, risk of cardiovascular disease, dementia, Alzheimer’s, and sarcopenia are all much higher. In fact, death to cancer is also much more common with low IGF-1 too, possibly due to increased risk of cachexia (muscle wasting).
While diseases associated with high IGF-1 levels are scary, the truth is that low IGF-1 levels are more likely to be of concern for many people. If you are worried about IGF-1 levels, perhaps the best action you can take is to exercise frequently. Frequent exercise cuts the risk of cancers associated with IGF-1 to a much greater extent than cutting animal protein does, and also doesn’t predispose you to the diseases associated with low IGF-1. In fact, the risk of all of the diseases associated with low IGF-1 are also reduced when you exercise frequently.
We encourage you to read the entire article below. This is part 1 of a 3 part segment. You’ll get loads of great information about exactly what IGF-1 does, how it affects our health, and how we can be sure do IGF-1 “the right way”–the way where we live a long, strong, disease-free life!
IGF-1: Does Meat Cause Cancer?
IGF-1 has been making headlines, and as is typical with the media, all the news is rich in sensationalism and scant on accuracy. The unfortunate side effect of this all-too-often is confusion. This article aims to clear that confusion and set your mind at ease.
In the news, you’ve probably read that IGF-1 determines longevity. It doesn’t, at least not directly in humans. A second common concern is that meat causes cancer. It doesn’t, although there are some correlations you should be aware of. Most recently, the headlines have read that eating a diet high in animal protein is bad for you, primarily because it increases IGF-1. Certainly animal protein increases IGF-1, but the study upon which these headlines are based didn’t offer such a dramatic prognosis.
Before we really cover whether IGF-1 is good or bad, we need to briefly cover what exactly “IGF-1” is. After we know what it is, and why we need it, then we can approach the more complicated topics of IGF-1 and longevity, cancer, and disease, and also whether animal protein is actually good or bad.
Some common sense dictates that there are different types of animal protein that should be taken into consideration. Dairy products contain high levels of dioxins, which are proven potent carcinogens. So the argument could be made that toxic dairy foods can cause cancer. Factory meat also contains high levels of dioxins. However, when you read through this article, you’ll see that IGF-1 itself works in a much different way than those people who simply say “IGF-1 fuels cancer.”
What Is IGF-1?
IGF-1 stands for “insulin-like growth factor 1”, and as the name implies, it performs a similar sort of job as insulin. Most people know that insulin is related to blood glucose, and maybe that insulin helps the body move that glucose into different organs (such as the muscles or the fat).
We usually think of insulin being released in relation to a high-carbohydrate meal, but in reality both carbohydrates and protein are well-capable of raising insulin. IGF-1 release is more complicated, with multiple interactions with other hormones such as growth hormone, but ultimately it appears to be correlated with animal protein intake (particularly dairy) and also fat intake. Since carbohydrates can increase insulin, and insulin can affect IGF-1, there is some correlation with carbohydrates, but overall it doesn’t appear to be as strong as the correlation between animal protein and fats.
What most people don’t realize is that insulin is actually our body’s #1 most important anabolic hormone!
Briefly, we can divide our body’s metabolism into two camps: anabolic reactions, or reactions that build something, and catabolic reactions, or reactions that break something down. We need both of them, and depending on the context, both can be highly positive or incredibly damaging.
We can’t say that insulin or IGF-1 are completely good or completely bad–depending on the context, they can be extremely helpful or potentially harmful hormones.
For example, if you just trained hard, then you want anabolic reactions to occur because that’s how your muscles grow. In this case, insulin brings glucose and amino acids into the muscle and encourages muscle growth.
On the other hand, if you’ve been sitting at a desk all day and have a giant pile of fries for lunch, you haven’t stimulated the right conditions for anabolic reactions to be favored in the muscles. Instead, you’ll build your fat cells—not the result most people are looking for.
Both the muscle-building process and the fat-storage process are anabolic reactions, but one is generally considered to be positive and the other negative. On the far end of the spectrum, a cancer cell grows via anabolic reactions.
Ultimately, we can’t say that insulin is definitely good or definitely bad; we can only say that depending on the context, it may promote health or harm. Optimally, you want to do everything you can to encourage insulin’s healthy effects, not its harmful effects, but sometimes it’s not such an easy distinction to make!
On a molecular level, IGF-1 is very similar to insulin, and is similarly anabolic. IGF-1 helps children develop physically into adults, and it continues to help adult cells to grow and divide. Without healthy levels of IGF-1, children fail to develop properly, resulting in dwarfism, and adults lose muscle mass and suffer from overall weakened strength.
The main point here is that context is highly important when it comes to discussing IGF-1—it’s not as simple as saying that IGF-1 is good or that it’s bad. When IGF-1 is helping the muscles adapt to exercise, it’s good, whereas when IGF-1 is helping cancer cells to divide and develop a blood supply (angiogenesis), it’s bad. This context is why it’s so important to consider lifestyle along with diet when approaching IGF-1, and why we need to take some of the sensationalistic headlines with a grain of salt.
Does IGF-1 Cause Cancer?
The short answer to this is “no”—IGF-1 doesn’t cause cancer, though it may allow cancerous cells that already exist to grow faster. Even this process is somewhat more nuanced than people who strongly link IGF-1 and cancer would have you believe.
A meta-analysis of studies examining the correlation between high IGF-1 levels and different cancers only found increased risk of prostate and pre-menopausal breast cancers, suggesting that perhaps it’s premature to say that high levels of IGF-1 would predispose someone to cancer. There are many more cancers, and many more deadly cancers, that did not appear to be highly correlated.
A second meta-analysis observed that men with low IGF-1 levels actually had significantly higher risk of death due to cancer than men with normal (not high) levels. In this case, no studies involving cancer risk and IGF-1 in women were included, so we cannot assume the same will be true in women–though we might expect it to be similar given our knowledge of how IGF-1 affects the human body.
At most, what we can say we relative certainty is that having high levels of IGF-1 may increase your risk of developing breast or prostate cancer. What we cannot say for certain is that low levels will decrease your risk above and beyond simply aiming for normal levels—in fact, as just mentioned, research actually shows a greater risk of death due to cancer when IGF-1 levels are low, possibly because of cancer-induced cachexia (muscle wasting often seen in cancer and other chronic diseases).
Cancer is associated with both high levels of IGF-1 and low levels!
Cachexia is a condition associated with IGF-1 deficiency, and is thought to be responsible for upwards of 30% of all cancer deaths (as opposed to the cancer itself). Around 50% of patients with cancer die in a state of cachexia. Overall, preventing cachexia is an important part of treating cancer, and this means that IGF-1 needs to be kept at an optimal level—not too high, not too low. Therefore, attempting to cut IGF-1 drastically is not a recommended strategy, and could very likely cause more problems!
Another link which frequently makes headlines is that eating animal protein is correlated with cancer. In reality, apart from processed meat, we can’t actually make a strong link. One study found only a non-significant increase in risk for prostate cancer associated with animal protein consumption (though it did find a significant, but still very minor increase due to dairy—roughly 22% increased risk). Overall, total protein intake from all animal and plant sources was not associated with risk at all.
Other studies just look at potential risk factors which may be increased when animal protein is consumed. In one study, researchers measured changes in IGF-1 and its binding protein “IGFBP-3” (which is also associated with cancer risk) when calories are protein are restricted. Sure enough, they found that reducing protein intake also reduced IGF-1 and IGFBP-3 levels—but this doesn’t say much about actual risk of cancer, only that animal protein is associated with IGF-1 levels.
In another case, three diets/lifestyles were compared:
- A calorie/protein-restriction group
- A group of endurance runners
- A “standard American diet” (SAD) group
What they found was that even though protein intake was by far the highest in the endurance runner group, IGF-1 levels were NOT the highest in the runners. The group with the highest IGF-1 levels was the SAD group, suggesting that we can’t blame protein alone for high IGF-1 levels—we need to look at lifestyle too.
Furthermore, IGFBP-3 was actually the lowest in the endurance group (though overall there was no significant difference).
Even though the group of endurance runners ate around 200% the protein as the calorie-restriction group, IGF-1 was actually highest in the middle-of-the-road SAD diet.
So it comes back to context again—who’s at higher risk for a disease associated with high levels of anabolic hormones: an athlete who will use those hormones to develop stronger muscles, or a sedentary individual who isn’t creating the conditions needed to grow muscles and in whom IGF-1 will mostly feed unhealthy processes?
When we examine the context, it’s easier to distinguish between when we might worry about high IGF-1 levels and when we might assume it’ll be beneficial. This still isn’t the whole picture, though. We need to understand how else IGF-1 affects disease beyond just cancer, because as it turns out, cancer is actually only a fraction of the picture!
If Brian Rigby’s deep dive into IGF-1 hormone resonates with you and you would like to reduce your meat intake, but still need to ensure protein intake levels, we recommend the Reset360 All-in-One Shake.