Postmenopausal women who ate high levels of plant protein had lower risks of premature death, cardiovascular disease death, and dementia-related death compared with women who ate less plant protein, according to new research from University of Iowa College of Public Health investigators.
Previous research has shown an association between diets high in red meat, a major type of dietary proteins in the United States and worldwide, and cardiovascular disease risk, yet the data are sparse and inconclusive about other specific types of dietary proteins, the study authors say.
Researchers led by Wei Bao, assistant professor of epidemiology, analyzed data from more than 100,000 postmenopausal women ages 50 to 79 who participated in the national Women’s Health Initiative study between 1993 and 1998. Study participants were followed through February 2017.
At the time they enrolled in the study, participants completed questionnaires about their diet detailing how often they ate eggs, dairy, poultry, red meat, fish/shellfish, and plant proteins such as nuts, tofu, beans, and peas.
During the study period, a total of 25,976 deaths occurred (6,993 deaths from cardiovascular disease; 7,516 deaths from cancer; and 2,734 deaths from dementia).
Researchers noted the levels and types of protein women reported consuming, then divided them into groups to compare who ate the least and who ate the most of each protein.
Among the study’s key findings:
- Compared to postmenopausal women who had the least amount of plant protein intake, those with the highest amount of plant protein intake had a 9% lower risk of death from all causes, a 12% lower risk of death from cardiovascular disease, and a 21% lower risk of dementia-related death.
- Higher consumption of processed red meat was associated with a 20% higher risk of dying from dementia.
- Higher consumption of unprocessed meat, eggs, and dairy products was associated with a 12%, 24%, and 11% higher risk of dying from cardiovascular disease, respectively.
- Higher consumption of eggs was associated with a 10% higher risk of death due to cancer. However, higher consumption of eggs was associated with a 14% lower risk of dying from dementia.
- Higher poultry consumption was associated with a 15% lower risk of dying from dementia.
Researchers also noted that substitution of 5% energy of animal protein with plant protein was associated with a 14% lower risk of deaths from all causes, a 22% lower risk of deaths from cardiovascular disease, and a 19% lower risk of deaths from dementia. For specific types of dietary proteins, substitution of total red meat, eggs, or dairy products with nuts was associated with a 12% to 47% lower risk of death from all causes depending on the type of protein replaced with nuts.
“Our findings support the need to consider dietary protein sources in future dietary guidelines,” says Bao. “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.”
The study, published in the Journal of the American Heart Association, had several limitations including that it was observational, based on self-reported data at the beginning of the study, and lacked data on how the proteins were cooked. In addition, all the study participants were postmenopausal women, and therefore it is unclear whether the findings apply to younger women or men.
In addition to Bao, other University of Iowa investigators contributing to this study include Yangbo Sun, Buyun Liu, Linda Snetselaar, and Robert Wallace. The study was funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health and the U.S. Department of Health and Human Services.
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