Re-post of key points in article about the link between high protein diets and cancer

High-Protein Diet Raises Cancer Risk As Much As Smoking

By Bahar Gholipour March 04, 2014

 The link between high-protein intake and risk of cancer almost vanished when the researchers considered participants whose protein mainly came from plants, such as beans.

This may be because proteins in plants have a different composition, and don't stimulate growth hormones as efficiently as meat proteins, Longo said.

The study suggests that the Mediterranean diet, which is low in animal protein and high in carbohydrates, may be best for extending life span, Longo said.

The researchers said they recommend eating about 0.8 grams of protein per kilogram of body weight every day in middle age. For example, a 130-pound person should eat about 45 to 50 grams of protein a day, with a preference for plant proteins, the researchers said.

To investigate why there may be a link between protein consumption and cancer, the researchers looked at mice that were injected with mouse skin cancer cells. They showed that a high amount of protein in the mouse diet promoted the tumor's survival and growth by increasing the levels of a growth hormone, called IGF-1.

The researchers also measured the levels of IGF-1 for 2,000 people, randomly selected among those in their study, and found that for every 10 nanograms per milliliter increase in IGF-1, those on a high-protein diet were 9 percent more likely to die of cancer than those on a low-protein diet.

"When you have a lot of protein, these growth factors go up, and we've shown that they help normal cells become cancer-like cells, and then they help the cells grow," Longo said.(https://www.livescience.com/43839-too-much-protein-help-cancers-grow.html)