High meat and cheese consumption in middle age ups cancer risk
A diet high in animal protein may increase risk of cancer among people between ages 50 and 65, according to a long-term study conducted by scientists from the University of Southern California (USC).
The study involved more than 6,000 people ages 50 and older, whom were followed for 18 years. The researchers found that the people who generally consumed meals high in animal proteins were four times more likely to die of cancer than those who followed a diet low in animal proteins.
The research team conducted two additional studies—one in mice and one in humans—to better understand the link between protein consumption and cancer. In the first study, the researchers injected mice with mouse skin cancer cells. They found that the tumors were more likely to survive and grow in the mice who consumed a high amount of protein. In the second study, researchers looked at data on 2,000 people and found that the participants who followed a diet high in animal protein were about 9 percent more likely to die of cancer than those who followed a diet low in animal protein. Researchers were able to attribute the increased cancer risk among both the mice and humans to increased levels of a growth hormone called IGF-1.
The study’s findings, published in the journal Cell Metabolism, suggest that diets high in animal proteins—including meat, milk and cheese—may be particularly harmful for middle-aged people. Researchers defined a “high-protein” diet as one where at least 20 percent of its calories come from protein. Researchers recommended that people eat about 0.8 grams of protein per kilogram of body weight daily during middle age, and they suggested that people aim to get much of their protein from plant sources, as plant protein does not stimulate growth hormones as much as do meat proteins. However, they added that because people at different ages have different dietary needs, consumers should speak with their health care provider before drastically altering their diet.