This article is more than 5 years old. Information may no longer be current.

Substituting plant protein for animal protein lowers risk of death

High plant protein intake is inversely associated with mortality, compared with high animal protein intake, which is positively associated with mortality, according to findings published in JAMA Internal Medicine.

Researchers reported that replacing animal protein with plant protein may result in considerable health benefits, particularly for individuals who have other unhealthy behaviors or conditions.

“Defining what represents a macronutritionally balanced diet remains an open question and a high priority in nutrition research,” Mingyang Song, MD, ScD, from the clinical and translational epidemiology unit in the division of gastroenterology at the Massachusetts General Hospital and Harvard Medical School, and colleagues wrote. “To date, data examining protein sources in relation to mortality are sparse. Therefore, we used data ... to prospectively examine animal protein vs plant protein in relation to the risk for all-cause and cause-specific mortality and to perform an isocaloric substitution analysis for a variety of food sources of protein.”

The researchers examined how protein sources affect a macronutritionally balanced diet. They studied the associations of animal and plant protein intake with risk of mortality.

The study included a total of 131,342 participants from the Nurses’ Health Study and Health Professionals Follow-Up Study. The participants were asked how often they consumed various foods at a standardized portion size. Sources of animal protein included red meat, poultry, fish, eggs, and dairy products, while sources of plant protein included bread, pasta, nuts, beans, and legumes.

The median protein intake was 14% for animal protein (5th to 95th percentile, 9%-22%) and 4% for plant protein (5th to 95th percentile, 2%-6%), as assessed by percentage of energy. After factoring in lifestyle and dietary risk factors, they found that animal protein intake was slightly associated with higher mortality, with a hazard ratio of 1.08 per 10% energy increment (95% CI, 1.01-1.16; P = .04). Plant protein intake, was associated with lower mortality, with a hazard ratio of 0.9 per 3% energy increment (95% CI, 0.86-0.95, P < .001). These findings, however, were confined to participants who posed at least one unhealthy lifestyle factor, including smoking, physical inactivity, obesity/overweight, and heavy alcohol consumption; these associations were not present among those without these risk factors.

“Although short-term randomized clinical trials have shown a beneficial effect of high protein intake, the long-term health consequences of protein intake remain controversial,” Song and colleagues wrote. “Substitution of plant protein for animal protein, especially from processed red meat, may confer a substantial health benefit. Therefore, public health recommendations should focus on improvement of protein sources.” – by Rafi Naseer

Disclosure: The researchers report no relevant financial disclosures.