Study: Too Much Protein Ups Your Cancer Risk
How much protein should you really be eating? Popular diets like Atkins and Paleo tout a combination of animal-based lean proteins and fruits and veggies to help people lose weight, but a new study is challenging their commonly-held advice.
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U.S. and Italian scientists tracked more than 6,000 men and women for 18 years and concluded that people between ages 50 and 65 who had moderate-to-high protein intake are four times more likely to die of cancer and heart disease than those following a low-protein diet. They were also at a higher risk for diabetes. What counts as "high-protein"? A diet in which at least 20% of calories came from protein; "low-protein" meant less than 10%.
"The majority of Americans could reduce their protein intake," said study co-author Valter Longo, a University of Southern California gerontology professor and director of the school's Longevity Institute. "The best change would be to lower the daily intake of all proteins, but especially animal-derived proteins." Plant sources (legumes, nuts) didn't raise relative risk, the study found.
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But what's good for us at one age could kill us at another, researchers said. After the age of 65, people were in better health if they increased their protein in order to combat the muscle and weight loss that occurs in old age. Longo recommends that middle-aged adults follow the Centers for Disease Control and Prevention (CDC) recommendation to eat about 0.8 grams of protein per kilogram of body weight each day. Translation: About 8.5 ounces for a 150-pound person.
Nutritionist Stephanie Middleberg, M.S., R.D., echoed the CDC advice, but warned that not all proteins are created equal: "I encourage clients to try a mix of plant-based and animal proteins and to look for words like 'grass-fed,' 'made without hormones,' 'organic,' and 'pasture-raised' when possible."
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Lauren Slayton, M.S., R.D., another nutritionist, was even more skeptical of the study in a post on her blog, "Scientists want their work to get attention, may have hidden agendas, and can twist their 'data' in ways not all that different from my husband telling me, 'I need to go with these guys from work to the Ranger game, it's important for business,'" she wrote, pointing out some interesting connections between the study co-author and a company that makes meat replacement products.
Slayton's advice: Reduce the amount of protein you consume as the day goes on. It's best to eat protein at breakfast to help control your appetite and at lunch, because it helps us with alertness. But at dinnertime, we don't need to be as alert. This is the time to go for healthy carbs and lots of veggies. Both Slayton and Middleberg say your protein serving size per meal should be about the size of a smartphone (or if you don't have one of those nearby, use your fist as a guide).
- By Natalie Gontcharova
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