Eating more plant protein is associated with lower risk of death.


Eating more protein from plant sources was associated with a lower risk of death, and animal protein was associated with a higher risk of death, in people with at least one lifestyle risk factor such as smoking or being overweight, research published in JAMA Internal Medicine has shown. The prospective cohort study included 131 342 participants from the Nurses’ Health Study and the Health Professionals Follow-Up Study. Diet and other lifestyle data were collected every two years, and participants were followed up for as long as 32 years. After the researchers adjusted for major lifestyle and dietary risk factors they found that every 10% increment of animal protein intake 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 (hazard ratio 1.08 (95% confidence interval 1.01 to 1.16); P for trend=0.04). In contrast, eating more plant protein was associated with a 10% lower risk of death from all causes with every 3% increment of total calories and a 12% lower risk of cardiovascular death (0.88 (0.80 to 0.97); P for trend=0.007). However, the associations were confined to participants with at least one unhealthy lifestyle factor such as smoking, heavy alcohol intake, overweight or obesity, and physical inactivity, but they were not evident in people without any of these risk factors. The study also found that replacing animal protein with plant protein was associated with lower mortality. For example, substituting 3% of calories from processed red meat with an equivalent amount of protein from plants reduced the risk of all cause mortality (0.66 (0.59 to 0.75)). The researchers said that substituting plant protein for animal protein, especially replacing processed red meat, may confer a substantial health benefit and that public health recommendations should focus on improving protein sources. Tim Key, professor of epidemiology and deputy director of the Cancer Epidemiology Unit at the University of Oxford, commented, “This is a high quality analysis of two long term observational studies. In this type of study it is important to examine whether the results seen could actually be due to confounding by other dietary and non-dietary factors—for example, in this study the people eating the most plant protein were slimmer and less likely to smoke than those eating the least, which would be expected to reduce their risk for mortality. “The authors made extensive adjustments for such potential confounding factors, and although some statistically significant associations remained, the adjustments did tend to weaken the associations, [suggesting] that the results may still be influenced by some residual confounding.” He concluded, “Overall, the study adds to the view that healthy diets should emphasise plant foods, including plant sources of protein, and that intakes of animal source foods—especially processed meat—should be low.” Ian Johnson, nutrition researcher and emeritus fellow at the Institute of Food Research, said, “This interesting and robust work seems to support the growing consensus that diets based largely on plant foods are better for long term health than diets containing large quantities of meat and dairy products, but it tells us little about mechanism. “It is far from clear whether plant proteins are protective or animal proteins are detrimental to health, or whether these protein levels are simply markers for something else.”

DOI: 10.1136/bmj.i4243

Cite this paper

@article{Wise2016EatingMP, title={Eating more plant protein is associated with lower risk of death.}, author={Jacqui Wise}, journal={BMJ}, year={2016}, volume={354}, pages={i4243} }