The largest study to ever look at the effects of different sources of protein found that eating lots of protein from plants was associated with a lower risk of death.
"Overall, our findings support the importance of the sources of dietary protein for long-term health outcomes," the study’s author, Mingyang Song, MD, ScD, a research fellow in the Massachusetts General Hospital, said in a release from Mass Gen. "While previous studies have primarily focused on the overall amount of protein intake—which is important—from a broad dietary perspective, the particular foods that people consume to get protein are equally important. Our findings also have public health implications and can help refine current dietary recommendations about protein intake, in light of the fact that it is not only the amount of protein but the specific food sources that is critical for long-term health."
The study, published in August in JAMA Internal Medicine, analyzed data from the Nurses' Health Study and the Health Professionals Follow-up Study, which have compiled comprehensive health data on more than 170,000 participants since the 1980s. In addition to completing overall health questionnaires every two years, participants provided information on their dietary intake every four years. The researchers analyzed more than 30 years of data for NHS participants and 26 years of data for HPFS participants.
They found that a high consumption of protein from animal sources—any types of meat, eggs or dairy—was not associated with all-cause mortality. The elevated mortality risk only applied to subjects who also had at least one factor associated with an unhealthy lifestyle, such as being obese or underweight, heavy drinkers, smokers, or not physically active. On the other hand, high consumption of protein from plant sources was associated with a lower all-cause mortality rate.
"Our findings suggest that people should consider eating more plant proteins than animal proteins, and when they do choose among sources of animal protein, fish and chicken are probably better choices,” Song said. “Future studies should examine the mechanisms underlying the different effects of plant and animal proteins—along with different sources of animal proteins—on overall health."