After analysing data gathered from 131,000 people over three decades, scientists at Massachusetts General Hospital have found that swapping meat for lentils will substantially reduce death rates.
Mortality from heart disease fell 12 per cent, and deaths from all causes fell by 10 per cent, for every three per cent increase in calories from plant protein, the researchers found.
In contrast, raising the animal protein share of calories by 10 per cent led to an eight per cent greater chance of dying from a heart problem, and two per cent higher risk of all-cause death.
Replacing processed red meat for a total vegan diet of vegetables, nuts and cereals saw the biggest drop in death rates, of 32 per cent.
Substituting eggs for plant protein led to a 19 per cent reduction in death risk, and swapping out unprocessed red meat saw a 12 per cent drop.
Animal protein foods include all types of meat, fish, eggs and dairy products such as milk and cheese.
Plant sources of protein in a vegan diet include cereals, beans, nuts, legumes, soya and bread.
“Overall, our findings support the importance of the sources of dietary protein for long-term health outcomes,” says lead scientist Dr Mingyang Song.
“While previous studies have primarily focused on the overall amount of protein intake – which is important – from a broad dietary perspective, the particular foods people consume to get protein are equally important.
“Our findings suggest 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.”
The research, published in the journal JAMA Internal Medicine, found the link between animal protein was highest among people who were obese, had a history of smoking, drank heavily, and who did little exercise.
Among the healthiest participants, the link disappeared – which the researchers said was probably because health-conscious people were already eating more fish and poultry rather than red and processed meat.