People who eat more protein from plants and less from animal may live longer even when they have unhealthy habits like heavy drinking or smoking, finds a large U.S. study from Harvard University and Massachusetts General Hospital in Boston.
The findings suggest that when it comes to protein, where it comes from may be just as important as how much people eat.
The study followed 131,00 men and women – all health professionals – for 32 years to see if there was an association between animal and plant protein intake and the risk of dying or mortality. Every four years, participants were asked about their diet, so there were many data points.
By the end of the study, about 36,000 people died – about 8,850 of cardiovascular disease and roughly 13,000 of cancer.
The researchers found that animal protein intake was linked with a higher risk of death, especially death caused by cardiovascular disease. A higher plant protein intake, on the other hand, was tied to a lower risk of mortality.
Harmful effect of animal protein stronger for obese individuals, heavy drinkers
But these findings were only apparent in people who had at least one unhealthy lifestyle risk factor such as smoking, heavy alcohol intake, overweight, or physical inactivity. The link between higher animal protein and mortality was most pronounced in people who were obese and those who were heavy drinkers.
The harmful effect of high intakes of animal protein and the beneficial effect of eating more plant protein may only be evident in people who already have underlying inflammation or metabolic disorders as often seen in obesity.
Increased mortality risk largely tied to processed meats
Red meat, especially processed meats like bacon, sausage, hot dogs and salami, were strongly associated with mortality whereas chicken and fish were not.
The researchers also estimated that swapping 3% of your daily calories that comes from processed red meat for an equal amount of plant protein like beans, nuts, tofu, whole grains would lower the risk of mortality by 34%. Again, the association was strongest for dying from CVD.
Animal protein, however, didn’t appear linked to higher mortality for people with a healthy lifestyle. For these people, eating more plant protein also didn’t seem tied to a longer life.
Because the study was observational, it can’t prove that the type of protein people eat directly influences how long they may live. It’s also possible that the eating and lifestyle habits of healthcare workers might not be representative of the broader population of adults.
This study adds to the existing evidence pointing to the importance of eating plenty of healthier plant-based foods such as fruits, nuts, seeds, beans and lentils, whole grains and non-starchy vegetables.
Source: JAMA Internal Medicine, online August 1, 2016.
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