Switch from steak to soy for a longer life

Researchers from Harvard Medical School have shown that substituting animal protein for plant-sourced protein is associated with a lower risk of death.

In the study, published online by JAMA Internal Medicine, Mingyang Song, M.D., Sc.D., of Massachusetts General Hospital and Harvard Medical School, and coauthors used data from two large US studies that had repeated measures of diet through food questionnaires and up to 32 years of follow-up. They examined hazard ratios (risk) for all-cause and cause-specific mortality in relation to eating animal protein vs plant protein.

Among the 131,342 study participants, 64.7% were women and the average age of participants was 49. Median protein intake, measured as a percentage of calories, was 14% for animal protein and 4% for plant protein.

After adjusting for major lifestyle and dietary risk factors, every 10% increment of animal protein from total calories was associated with a 2% higher risk of death from all causes and an 8% increased risk of death from cardiovascular disease.

Eating more plant protein was associated with a 10% lower risk of death from all causes for every 3% increment of total calories and a 12% lower risk of cardiovascular death.

Increased mortality associated with animal protein was more pronounced among participants who were obese and those who drank alcohol heavily.

The association between eating more plant protein and lower mortality was stronger among study participants who smoked, drank at least 14 g of alcohol a day, were overweight or obese, were physically inactive or were younger than 65 or older than 80.

Substituting 3% of calories from animal protein with plant protein was associated with a lower risk of death from all causes: 34% for replacing processed red meat, 12% for replacing unprocessed red meat and 19% for replacing eggs.

The study concluded: “Substitution of plant protein for animal protein, especially from processed red meat, may confer substantial health benefit. Therefore, public health recommendations should focus on improvement of protein sources.”