March 4, 2014
High Protein Diet Raises Risk Of Cancer By 75 Percent
Lee Rannals for redOrbit.com - Your Universe Online
University of Southern California (USC) researchers say that meat and cheese could be just as bad for you as smoking a cigarette.
“There’s a misconception that because we all eat, understanding nutrition is simple. But the question is not whether a certain diet allows you to do well for three days, but can it help you survive to be 100?” Valter Longo, Edna M. Jones Professor of Biogerontology at the USC Davis School of Gerontology and director of the USC Longevity Institute, said in a statement.
The study draws from previous findings on the growth hormone IGF-I, which helps our bodies grow but has also been linked to cancer susceptibility. Levels of this growth hormone drop off dramatically after age 65, which could cause fragility and muscle loss. The latest study shows that although high protein intake during middle age is harmful, it could be protective for older adults.
"The research shows that a low-protein diet in middle age is useful for preventing cancer and overall mortality, through a process that involves regulating IGF-I and possibly insulin levels," co-author Eileen Crimmins, the AARP Chair in Gerontology at USC, said in a statement. "However, we also propose that at older ages, it may be important to avoid a low-protein diet to allow the maintenance of healthy weight and protection from frailty."
Researchers found that plant-based proteins did not seem to have the same mortality effects as animal proteins, and rates of cancer and death did not seem to be affected by controlling carbohydrate or fat consumption. By process of elimination, they discovered that animal protein was the main culprit.
"The majority of Americans are eating about twice as much proteins as they should, and it seems that the best change would be to lower the daily intake of all proteins but especially animal-derived proteins," said Longo, co-author of the paper published in Cell Metabolism. "But don't get extreme in cutting out protein; you can go from protected to malnourished very quickly."
The findings support other expert health recommendations that say to consume only about 0.02-ounces of protein per pound of body weight each day in middle age. The team defined a “high-protein” diet as deriving from at least 20 percent of calories from protein, including plant-based and animal-based. A “moderate” protein diet includes 10 to 19 percent of calories from protein, and a “low-protein” diet includes less than 10-percent protein.
The researchers found that even moderate amounts of protein in the diet could be causing health problems for middle aged people. They said that people in the study who ate a moderate amount of protein were still three times more likely to die of cancer than those who ate a low-protein diet.
"Almost everyone is going to have a cancer cell or pre-cancer cell in them at some point. The question is: Does it progress?" Longo said. "Turns out one of the major factors in determining if it does is is protein intake."