Plant Protein Intake Linked to Lower Risk of All-Cause, Cardiovascular Death Among Aging Women

Wei Bao, MD, PhD

An analysis of data from a major women’s health study is underlining the impact of increased consumption of plant protein on risk of death, cardiovascular disease, and dementia-related death among older women.

Funded by the National Institutes of Health and National Heart, Lung, and Blood Institute, results of the study provide valuable insight to clinicians and add to the ongoing conversations surrounding dietary science and nutrition.

"Our findings support the need to consider dietary protein sources in future dietary guidelines," said study lead investigator Wei Bao, MD, PhD, an assistant professor of epidemiology at the University of Iowa in Iowa City, in a statement from the American Heart Association. "Current dietary guidelines mainly focus on the total amount of protein, and our findings show that there may be different health influences associated with different types of protein foods."

Despite an almost innumerable number of studies examining plant versus animal protein and other sources of nutrition, debate still exists surrounding the effectiveness of increased protein from either source on overall, but particularly, cardiovascular health. For the purpose of their study, investigators designed their analysis to use data from postmenopausal women enrolled in the Women’s Health Initiative from 1993-1998 and followed through February 2017.

Of the 142,267 women considered eligible for inclusion in the current study, 137,481 had information related to a valid food frequency questionnaire. From this group, investigators excluded 137 with missing data on postmenopausal hormone therapy use, 24,427 who had a history of cardiovascular disease at baseline, and 10,366 women with a history of cancer at baseline. In total, 102,521 women were selected for inclusion.

During 1,876,205 person-years of follow-up, a total of 25,976 deaths occurred, including 6993 from cardiovascular disease, 7516 from cancer, and 2734 from dementia. Specific causes of cardiovascular disease included 776 from definite coronary heart disease, 1808 from cerebrovascular disease, 140 from pulmonary embolism, 2120 from possible coronary heart disease and 2149 from other or unknown cardiovascular diseases. The most common form of cancer among those who died included lung cancer, breast cancer, and pancreatic cancer. Based on results of validated FFQ responses, investigators categorized patients into quintiles based on the consumption of various forms of protein reported.

When comparing the highest quintile of plant protein consumption to the lowest, consumption of plant protein was inversely associated with all-cause mortality (HR, 0.91; 95% CI, 0.86-0.96), cardiovascular disease mortality (HR, 0.88; 95% CI, 0.79-0.97), and dementia mortality (HR, 0.79; 95% CI, 0.67-0.94).

When assessing other major protein sources, those in the highest quintile of consuming processed red meat (HR, 1.06; 95% CI, 1.01-1.10) and consuming eggs (HR, 1.14; 95% CI, 1.10-1.19) was associated with increased risk of all-cause mortality. Additionally, analyses indicated being in the highest quintile for consumption unprocessed red meat(HR, 1.12; 95% CI, 1.02-1.23), eggs (HR, 1.24; 95% CI, 1.4-1.34), or dairy products (HR, 1.11; 95% CI, 1.02-1.22) was associated with greater risk of cardiovascular disease mortality. Further analysis also revealed egg consumption was associated with a higher risk of cancer mortality (HR, 1.10; 95% CI, 1.02-1.19).

When evaluating dementia mortality, investigators found processed red meat was associated with a greater risk of dementia mortality while consumption of poultry was associated with a lower risk. Investigators also highlighted a substitution analysis suggested substituting animal protein with plant protein was associated with a lower risk of all‐cause mortality, cardiovascular disease mortality, and dementia mortality. Furthermore, this same analysis suggested substitution of total red meat, eggs, or dairy products with nuts was associated with a lower risk of all‐cause mortality.

“It is important to note that dietary proteins are not consumed in isolation, so the interpretation of these findings could be challenging and should be based on consideration of the overall diet including different cooking methods,” said study investigator Yangbo Sun, MD, PhD, a postdoctoral research scholar at the University of Iowa in Iowa City and assistant professor of epidemiology at the University of Tennessee Health Science Center, in the aforementioned statement.

This study, “Association of Major Dietary Protein Sources With All‐Cause and Cause‐Specific Mortality: Prospective Cohort Study,” was published in the Journal of the American Heart Association.