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Meat and cheese may be as bad for you as smoking

06 Mar, 2014 | Labroots

Put the ketchup down and step away from that burger. As reported in Science Daily, a new study that tracked a large sample of adults for nearly two decades found that eating a diet rich in animal proteins during middle age makes you four times more likely to die of cancer than someone with a low-protein diet. That’s right up there with the mortality risk that comes with smoking. According to the study, which is scheduled to be published in Cell Metabolism, not only is excessive protein consumption linked to a dramatic rise in cancer mortality, but middle-aged people who eat lots of proteins from animal sources—including meat, milk and cheese— were 74 percent more likely to die of any cause within the study period than their more low-protein counterparts. They were also several times more likely to die of diabetes. Before this study, researchers had never shown a definitive correlation between high protein consumption and mortality risk. This study considers how biology changes as we age, and how decisions in middle life may play out across the human lifespan. "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," said co-author Eileen Crimmins, the AARP Chair in Gerontology at USC. "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." Protein controls the growth hormone IGF-I. IGF-I helps our bodies grow, but has been linked to cancer susceptibility. Levels of IGF-I drop off dramatically after age 65, leading to potential frailty and muscle loss. That may explain why the study found that high protein intake during middle age is harmful, but is protective for older adults: those over 65 who ate a moderate- or high-protein diet were less susceptible to disease. The type of protein you eat may also be a factor. The researchers found that plant-based proteins, such as those from beans, did not seem to have the same mortality effects as animal proteins. Rates of cancer and death also did not seem to be affected by controlling for carbohydrate or fat consumption, suggesting that animal protein is the main culprit.