Eating more animal protein increases risk of death, plant protein reduces it

People who eat more protein from plantsand less from animals may live longer even when they haveunhealthy habits like heavy drinking or smoking, a large U.S.study suggests.

The findings suggest that when it comes to protein, where itcomes from may be just as important as how much people eat, saidleadauthor Dr. Mingyang Song, a researcher at HarvardUniversity and Massachusetts General Hospital in Boston.

"Plants are a better source than animal products," Song saidby email.

"If people do have to choose among animal products, try toavoid processed red meat and choose fish or chicken instead,"Song added.

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The researchers noted thatprevious studies have indicatedeating fewer starchy foods and more protein can help people manage their weight, blood pressure, sugar and blood lipids. They thought that looking at details such as the effect of different protein sources could help them providemore specific adviceabout what to eat.

Song and colleagues followed more than 130,000 nurses andother health professionals over several decades. Half of theparticipants were getting at least 14 per cent of their caloriesfrom animal protein such as meat, eggs and dairy and at least fourper cent from plant protein sources such as pasta, grains,nuts, beans and legumes.

At the start of the study, participants were 49 years old onaverage. Most were women.

By the end of the study, about 36,000 people had died about8,850 of cardiovascular disease and roughly 13,000 of cancer.

After accounting for lifestyle factors such as smoking,drinking, obesity and physical inactivity, each threeper centincrease in calories from plant protein was associated with a 10per cent lower risk of death during the study period.

In contrast to the benefits seen with plants, each 10per cent increase in the proportion of calories from animalprotein was associated with a twoper cent higher risk of deathfrom any cause and an eightper cent increased risk of death fromcardiovascular disease during the study period.

Animal protein deadlierfor obese

This association between animal protein and mortality waseven stronger for people who were obese or heavy drinkers,researchers report in JAMA Internal Medicine.

"Obese individuals, as well as individuals with unhealthylifestyle choices are more likely to have underlying metabolic
or inflammatory disorders which could enhance the adverse effects of high animal protein intake," Dr. Pagona Lagiou, a
nutrition researcher at the University of Athens who wasn'tinvolved in the study,said by email.

The new study alsofound that meateaters with a healthy lifestyle tended to consumemore fish and poultry, while those with an unhealthy lifestyle and higher mortality risk such as those who were overweight and drank at least one alcoholic beverage per day tended to eat more red meat, eggs and high-fat dairy.

"So we suspect the different sources of animal protein between the two groups may contribute to the stronger results in the unhealthy lifestyle group," Song said in a news release.

Healthy lifestyle erases link

Animal protein, however, didn't appear linked to highermortality for people with a healthy lifestyle. For these people,
eating more plant protein also didn't seem tied to a longerlife.

Because the study was observational, it can't prove that thetype of protein people eat directly influences how long they maylive, the authors note. It's also possible that the eating andlifestyle habits of health-care workers might not berepresentative of the broader population of adults.

The real risk of mortality from animal protein also appearslargely tied to processed meat, such as bacon, salami and hot dogs, noted Dr. Dariush Mozaffarian,dean of the Tufts Friedman School of Nutrition Science andPolicy in Boston.

"Other animal source foods seem pretty neutral overall butrepresent a diverse group, from chicken to eggs to yogurt, forwhich we need to understand each of their specific healtheffects, outside any single isolated nutrient such as protein,"Mozaffarian, who wasn't involved in the study, said by email.

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"Based on a wealth of evidence, it's crucial to eats lots ofspecific, healthier plant-based foods: fruits, nuts, seeds,
beans, non-starchy veggies," Mozaffarian added. "But don't focuson 'plant-based' per se: a lot of the worst choices in the foodsupply are plant-based, from French fries to soda to white breadand white rice."

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