Insulin-like growth factor 1 (IGF-1) is a hormone that plays a crucial role in growth and development. While essential during childhood and adolescence, elevated IGF-1 levels in adulthood have been linked to an increased risk of cancer, accelerated aging, and other chronic diseases. This article explores the relationship between diet, IGF-1 levels, and overall health, providing guidance on dietary strategies to maintain optimal IGF-1 levels.
Understanding IGF-1
IGF-1 helps your cells grow and divide. As a hormone, IGF-1 assists with normal development in babies and children, and its natural presence in the body gradually decreases with age. Problems arise when IGF-1 continues to increase, rather than decrease as biologically programmed, throughout adulthood.
IGF-1 is a hormone that helps control the growth and development of organs, muscles, and tissues in the body. IGF-1 also has a hand in controlling glucose metabolism and brain function. It is produced primarily in the liver in response to growth hormone, with smaller amounts produced in other tissues. IGF-1 promotes cell growth, survival, and inhibits apoptosis (programmed cell death). It is important for normal development in babies and children, and its natural presence in the body gradually decreases with age.
The Link Between IGF-1 and Health Risks
While IGF-1 is necessary for growth and development, excessively high levels in adults can be detrimental. High IGF-1 activity can fuel abnormal cell growth, suppress apoptosis (the natural death of damaged cells), and drive the development of cancer. A meta-analysis of 19 studies including over 30,000 participants found that IGF-1 levels that are too high or too low are associated with a greater risk of early death.
Cancer
Studies have found that higher IGF-1 levels are not associated with overall protein, but animal protein intake, specifically. Associations exist between IGF-1 and the development of multiple types of cancer. IGF-1 can inhibit cell death, or apoptosis - a natural and healthy process by which old and damaged cells self-destruct for the good of the entire organism. Activation of IGF-signaling pathways promotes growth, metastasis, and even drug resistance in many types of human tumors. One study found that people ages 50 to 65 who ate a diet high in animal protein were four times more likely to die from cancer or diabetes - about the same relative risk as smoking cigarettes.
Read also: Diets of the Stars
- Breast Cancer: High circulating serum concentrations of IGF-1 in adults are associated with increased risk of postmenopausal breast cancer. A 2020 press release from the Annals of Oncology shared findings from two large studies conducted on the role of IGF-1 in breast cancer development. In the first study, researchers examined blood levels of IGF-1 among 206,263 women and their chances of developing the disease. Researchers used a method called Mendelian randomization to look at data from 265 variants of genes associated with IGF-1 concentrations to figure out if high levels of IGF-1 actually increase the risk of breast cancer.
- Colorectal Cancer: In a 2020 study based in the UK, researchers analyzed blood samples from almost 400,000 participants and found that a higher level of IGF-1 was associated with a higher risk for colorectal cancer. It turns out that IGF-1 is involved in activating multiple pathways that determine how aggressive a colorectal tumor may be.
- Prostate Cancer: High circulating serum IGF-1 levels are associated with a higher risk of developing advanced prostate cancer later in life.
Other Health Concerns
Beyond cancer, elevated IGF-1 levels have been implicated in other health issues, including:
- Type 2 Diabetes: Interestingly, another large observational study linked both low and high IGF-1 levels to type 2 diabetes risk. The role of IGF-1 in diabetes isn’t fully understood yet, beyond knowing that it’s best to have IGF-1 values in normal range.
Dietary Strategies for Lowering IGF-1
Dietary protein intake is the major regulator of IGF-1 levels, especially animal protein. The best strategy for keeping IGF-1 levels in check and preventing the type of cell overgrowth associated with multiple types of cancer is by replacing animal protein with plant protein.
Reducing Animal Protein Intake
Studies have found that higher IGF-1 levels are not associated with overall protein, but animal protein intake, specifically. That means all types of meat, dairy products, and eggs, which constitute about 30% of the standard American diet, are implicated. The reason animal protein triggers the release of IGF-1 may be because the relative ratios of amino acids in animal proteins closely resemble our own - so they send signals to our liver where IGF-1 is released. In a sense, upon eating animal products, the proteins in them deceive the human body into thinking it’s responding to its own amino acids.
- Replace animal protein with plant protein: Replace meat, eggs, and dairy with beans, lentils, tofu, nuts, and seeds. For example, substitute ingredients like beans, lentils, tofu, nuts, and seeds in meals where you might normally have meat. Try an unsweetened plant milk in place of dairy milk.
- Adopt a Nutritarian diet: Restricting animal protein during most of adult life to maintain a relatively low, but not excessively low IGF-1 is an important objective for those desirous of superior health and life extension. Unlike other plant-based diets that may fall short on protein in later life, the Nutritarian approach is designed to sustain optimal IGF-1 levels throughout life with plant protein-rich foods such as greens, beans (including soybeans), and seeds.
- Reduce consumption of milk: Our multinational case-only study (C.O.S.) on 3000 young women (<40 years of age) showed a significant positive association with high consumption of milk among women with a substantial probability of BRCA mutation. Milk directly stimulates insulin production or release, and it is associated with higher plasma levels of IGF-I.
Embracing a Plant-Based Diet
One study found that people on a vegan diet had significantly lower IGF-1 levels than people on a vegetarian or meat-eating diet. And vegans were better able to bind and remove excess IGF-1 in their bloodstreams.
- Vegan Diet: Studies suggest those who eat a vegan diet have lower levels of IGF-1 than meat-eaters and vegetarians. Looking at the chart below, they also have lower BMIs.
- Mediterranean Diet: BRCA mutation carriers in the intervention group enjoyed significant improvements in serum levels of IGF-I, IGFI-BP3 and IGF-I/IGFI-BP3 ratio compared to the control women. We succeeded in lowering serum levels of IGF-I by a comprehensive change in diet with moderate calorie and protein restriction, based on the traditional Mediterranean diet.
Specific Foods
- Soy: Breast cancer incidence is typically low in Asian countries where soy is commonly consumed.
- Seaweed: Seaweed also is consumed regularly in Asian countries where breast cancer risk is low. The combination of seaweed and soy significantly reduced this increase by about 40% (21.2 nmol/L for soy alone vs. 19.4 nmol/L).
Other Lifestyle Factors
Healthy food choices aren’t the only way to bring down your IGF-1 levels.
Read also: Unpacking weird and dangerous diets
Exercise
One study on men found that low-intensity aerobic training decreased the circulating levels of IGF-1 by nine percent (while also improving insulin sensitivity by 20%). But keep in mind that more isn’t always better. “Overtraining” also increases unfavorable IGF-1 levels and contributes to the increased incidence of hormone-dependent cancers and osteoarthritis.
Calorie Restriction
Long-term calorie restriction doesn’t appear to directly impact IGF-1 levels in humans, although it may make it less active.
Intermittent Fasting
In one study of 34 resistance-trained men, half ate normally while the other half followed a 16:8 intermittent fasting diet.
Recipes to Help Lower IGF-1
- Vegan Mince Lettuce Tacos: Use peas and corn, plus lots of colorful veggies, to create a “mince meat-like” appetizer (but without the meat). You can easily use minced veggies, legumes, and herbs in place of the conventional ground meat to create the same hearty and flavorful dish but with healing ingredients that won’t spike your IGF-1 levels. Create your own version by mincing or dicing any veggies you have on hand, and then adding them to the lentil, pea, and corn mixture.
- Herbed Cashew Cheese: Herbed Cashew Cheese creates a creamy and delicious-tasting cheese when you have the right ingredients (cashews and your favorite herbs) and the right equipment (a decent blender to get it extra creamy).
- Tempeh Chili: Swap out the red meat with tempeh and add even more plant protein with the beans. The result is a protein-powered, “meaty” textured, and delicious bowl of chili that won’t wreak havoc on your IGF-1 levels. Seems like a reasonable swap - you receive great protein, flavors, and textures but without harmful ingredients. Make this recipe for one and enjoy it throughout the week.
Monitoring IGF-1 Levels
If you’ve never had your IGF-1 levels tested, ask your doctor to include it in your next routine blood panel or use an at-home test, especially if you're over age 70.
Read also: Canine Gastroenteric Issues: A Diet Solution