The number of Americans who report following a plant-based diet has grown to 9.7 million, up from roughly 290,000 in 2004, according retail traffic data from Ipsos Retail Performance.
“Although emphasis has recently been placed on the importance of high-protein diets to overall health, a comprehensive analysis of long-term cause-specific mortality in association with the intake of plant protein and animal protein has not been reported,” wrote researchers of the study, published in JAMA Internal Medicine.
“This study provides evidence for public health recommendations regarding dietary modifications in choice of protein sources that may promote health and longevity.”
The research was supported in part by the Intramural Research Program of the US National Institutes of Health (NIH) National Cancer Institute.
Method and results
In the study, researchers analyzed data from 237,036 men (57%) and 178,068 women (43%) in the US National Institutes of Health–AARP Diet and Health Study from 1995 to 2011, which included a baseline food frequency questionnaire of dietary information, including intake of plant protein and animal protein. Research and analysis of the 16-years of past health data was conducted from October 2018 to April 2020.
Based on the data, researchers noted 77,614 deaths (49,297 men and 28,317 women) that occurred between 1995 and 2011.
“Adjusting for several important clinical and other risk factors, greater dietary plant protein intake was associated with reduced overall mortality in both sexes,” noted researchers.
The association between plant protein intake and overall mortality was similar across the subgroups of smoking status, diabetes, fruit consumption, vitamin supplement use, and self-reported health status, said researchers.
According to the study, replacement of 3% energy from animal protein with plant protein was inversely associated with overall mortality (risk decreased 10% in both men and women) and cardiovascular disease mortality (11% lower risk in men and 12% lower risk in women).
The lower overall mortality was attributable primarily to substitution of plant protein for egg protein (24% lower risk in men and 21% lower risk in women) and red meat protein (13% lower risk in men and 15% lower risk in women), said researchers.
While health associations between plant-based protein consumption and lower risk of CVD remain unclear, researchers hypothesize that "the coexisting bioactive nutrients in the plant food matrix" play a role in individual health outcomes. For example, plant-based proteins contain higher concentrations of nonessential amino acids (eg, arginine and glycine) and fewer essential amino acids (eg, methionine, lysine, and tryptophan), said researchers, which could potentially influence cardiovascular health through lower arterial stiffness or decreased systemic and vascular generation of reactive oxygen species.
"Other bioactive nutrients in foods may influence health, including heme iron, nitrates and nitrites, and sodium in red and processed meat and unsaturated fatty acids, antioxidants, vitamins, and trace minerals in plant-based foods," the study stated.
Informing public health recommendations
“In this large prospective cohort, higher plant protein intake was associated with small reductions in risk of overall and cardiovascular disease mortality. Our findings provide evidence that dietary modification in choice of protein sources may influence health and longevity,” researchers concluded.
"This study provides evidence for public health recommendations regarding dietary modifications in choice of protein sources that may promote health and longevity."
Dietary Guidelines Committee and plant-based diet
Included in its scientific report to inform USDA and the Department of Health and Human Services (HHS) as they develop the 2020-2025 Dietary Guidelines, the Dietary Guidelines Advisory Committee (DGAC) recommends dietary patterns that “provide the majority of energy from plant-based foods, such as vegetables, fruits, legumes, whole grains, nuts and seeds; provide protein and fats from nutrient-rich food sources; and limit intakes of added sugars, solid fats, and sodium.”