High-protein diets are a popular method of weight control. Although generally thought to be safe, some studies have shown a link between high-protein diets and cancer.
Physiology
Insulin-like growth factor-1 (IGF-1) is a protein hormone that has an anabolic (building up of organs and tissues) effect on the body. Diets high in protein have been shown to raise IGF-1 levels in the blood. IGF-1 may increase the likelihood of certain cells in the body becoming cancerous.
Effects
High levels of IGF-I in the blood have been linked to an increased risk for premenopausal breast cancer, prostate cancer and certain types of colon cancer.
Theories/Speculation
Some studies have shown that protein's effect on IGF-1 may depend on the protein source. Animal protein and soy protein have been shown to have a significant effect. One study showed that, in males, protein from poultry had a greater effect on IGF-1 levels compared to other protein sources.
Considerations
High-protein diets may also contribute to cancer risk because they often restrict carbohydrates. Certain carbohydrates such as fruits, vegetables and whole grains are rich in antioxidants that offer protection from certain cancers.
Prevention/Solution
A multitude of high-protein diets exist with varying guidelines on protein intake and allowances or restrictions of other macronutrients. Although studies examining high-protein diets and cancer risk have produced mixed results, it may be prudent to exercise moderation and be sure to include nutrient-rich, cancer-fighting foods into your diet.
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