A new study revealed that a high-protein diet may increase the risk of cancer and early death. Researchers of the University of Southern California, who performed the study, say that eating animal protein on a daily basis may be just as bad for health as smoking 20 cigarettes per day, especially for those under the age of 65.
For the study, researchers looked at 6,318 adults with an average protein intake of 16 percent, of which two-thirds came from animal protein. Results of the study show that those who have moderate levels of animal protein consumption have up to a three times higher risk of cancer and early death. According to researchers, a small decrease of protein intake resulted in a 21 percent reduction in risk.
Protein is linked to regulating the growth hormone IGF-I, which is known to increase the risk of cancer in middle-aged people; however, by the time a person hits the age of 65, the IGF-I hormone experiences a drop, causing poor muscle maintenance in the body. Co-author of the study, Eileen Crimmins, says, “The study clearly shows that a high-protein diet should be avoided by middle-aged people as this may increase the risk of cancer and early death, but we propose that those over the age of 65 maintain a high-protein diet to keep a healthy weight and to protect them from frailty.”
Co-author Dr. Valter Longo says that a high-protein diet is still important, as long as animal protein is reduced in the diet. “There are proteins that are better for the health than others. These are mainly plant-based proteins like beans and therefore vegans always come out on top in these types of studies. Overall, meat-lovers just do not do very well,” he says. The results of the study may ruin meals for meat-lovers, but Dr. Longo has some comfort. “There is no proof that proteins from fish may increase the risk of cancer and early death, so a diet of fish and vegetables is highly recommended.” Plant-based proteins also control for fats and carbohydrates in the diet, but these were not linked to an increase in risk of cancer and early death.
A previous study performed by Dr. Longo, showed that lowering the IGF-I not only reduces the risk of cancer, but also the risk of diabetes. His new study is an extension of his previous study and proves once again that diets such as Atkins and Paleo may not be beneficial for health after all.
In the U.S., people eat twice as much meat as the body requires. Researchers recommend Americans lower their protein intake to keep both a good diet and good health. Dr. Longo says, “It does not mean they should cut out animal protein all together, because it is very easy to go from protected to malnourished.” A protein intake of 0.8 grams per kilogram of body weight per day is the maximum for middle-aged people, according to the researchers of the University of Southern California.
Dr. Longo himself has always avoided a high-protein diet and with the results of his new study, he will keep doing so, as animal protein may increase the risk of cancer and early death.
By Diana Herst
Nature World News