What’s the Best Way to Lower Levels of IGF-1, the Cancer-Promoting Growth Hormone?

In the NutritionFacts.org video below, Dr. Michael Greger explores the link between obesity and the cancer-causing agent IGF-1* (insulin-like growth factor) produced by fat cells. Children and adults with a higher body mass index (BMI) typically have higher levels of IGF-1. We’ve also summarized his main points below.

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. So can one lower their levels of this cancer-causing hormone just by lowering their BMI?

For answers, Dr. Greger looked at studies that compared long distance runners to plant-based eaters. The runners had similar BMIs to the plant-based eaters, but still ate meat and dairy. Blood tests showed that those eating a low fat, plant-based diet still had lower levels of IGF-1 than long distance runners.

Whole plant-foods typically have fewer calories than those included in the Western diet. So could it be that vegans are simply eating fewer calories? When compared with people eating a calorie-restrictive diet, plant-based eaters still had the lowest levels of IGF-1.

While BMI is a factor in cancer risk, IGF-1 is lowest in those who eat a low-fat, whole foods plant-based diet. It is not how many calories, but which calories that seem to determine cancer risk. Watch the video to learn why scientists suggest, “reduced protein intake may become an important component of anticancer and anti-aging dietary interventions.”

*IGF-1: 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.

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