A new study has found that women who eat more protein from plant-based sources develop fewer chronic diseases and tend to be healthier as they age, compared to those who eat a lot of meat. Based on self-reports from almost 49,000 women, researchers found significantly less heart disease, cancer, and diabetes as well as fewer cognitive impairments and mental health declines in women who consumed more protein from plant-based sources including fruits, vegetables, nuts, beans and legumes, bread and pasta.
“Consuming protein in midlife was linked to promoting good health in older adulthood,” said lead author of the study, nutritional epidemiologist Andres Ardisson Korat, a scientist with the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University. Dr Ardisson Korat’s research focuses on food, nutrition and geriatric syndromes.
But Dr Ardisson Korat and collaborators found that simply increasing protein consumption was not enough.
“We also found that the source of protein matters,” Dr Ardisson Korat continued. “Getting the majority of your protein from plant sources at midlife, plus a small amount of animal protein seems to be conducive to good health and good survival to older ages.”
Amongst the study participants, the animal protein came from beef, chicken, seafood, milk, and cheese, whereas plant protein was derived from a wide variety of sources like bread, vegetables, fruits, pizza, cereal, baked items, mashed potatoes, nuts, beans, peanut butter, and pasta.
This study was based on analysis of surveys collected every four years between 1984 to 2016 by the Harvard-based Nurses’ Health Study. The surveys followed 48,762 female health care professionals who were between the ages of 38 and 59 (with an average age of 49) when the study was launched in 1984. At the start of the study, all participants were free from 11 common chronic diseases like heart disease, diabetes, and cancer, and they also had no physical or cognitive impairments. After about three decades of follow-up, this was still true for roughly 3,700 women, whom Dr Ardisson Korat and collaborators referred to as “healthy agers.”
Overall, the study participants got about 13% of their daily calories from animal protein, roughly 2% from dairy proteins, and approximately 5% from plant proteins. Dr Ardisson Korat and collaborators calculated total protein consumption by multiplying the frequency that each food item was consumed by its protein content and then, using the Harvard University Food Composition Database, totaling the amount of protein across all consumed food items.
According to their data analysis, Dr Ardisson Korat and collaborators found that women who ate more plant-based protein — originally defined in 1984 as protein obtained from bread, vegetables, fruits, pizza, cereal, baked items, mashed potatoes, nuts, beans, peanut butter, and pasta — were 46% more likely to be healthy into their later years. On the other hand, those who consumed more animal protein, such as beef, chicken, milk, cheese, fish or “seafood”, were 6% less likely to stay healthy as they aged.
“Those who consumed greater amounts of animal protein tended to have more chronic disease and didn’t manage to obtain the improved physical function that we normally associate with eating protein,” Dr Ardisson Korat stated.
Dr Ardisson Korat and collaborators then examined the study participants’ health. They compared the diets of women who didn’t develop any of the 11 chronic diseases they were looking for, nor did they lose a lot of either physical function or mental health, with the diets of those who did.
This analysis indicated that animal protein was modestly tied with fewer physical limitations in older age, but plant protein had a more robust and more consistent correlation across all observed models, and was also more closely linked with sound mental health later in life.
Dr Ardisson Korat and collaborators additionally found that heart disease, in particular, was tied to protein source: higher plant protein consumption was associated with lower levels of LDL cholesterol (“bad” cholesterol) and with lower blood pressure, along with increased insulin sensitivity. In comparison, higher animal protein intake was tied to higher LDL cholesterol and higher blood pressure, and with increased insulin-like growth factor, which has been detected in multiple cancers.
Perhaps surprisingly, dairy protein alone (mainly milk, cheese, pizza, yogurt, and ice cream) was not significantly associated with better health outcomes in older adulthood.
Dr Ardisson Korat and collaborators did acknowledge that the benefits of plant protein might be derived from components that naturally occur in plant-based foods, rather than from the protein itself because plants are full of a variety of beneficial elements such as higher dietary fiber and more micronutrients, such as polyphenols, that animal-based foods typically lack.
“The advantage of consuming more plant protein compared with other nutrients in the diet is that plant protein is associated with lower risk of cardiovascular disease and other chronic conditions,” Dr Ardisson Korat explained. “It promotes good physical function by enhancing muscle synthesis. And it comes from food sources that typically contain high-quality carbohydrates, such as dietary fiber, vitamins and minerals, and antioxidants.”
One aspect that this study didn’t investigate is which specific sources of plant-based protein might have the most benefits when it comes to healthy aging, or which animal proteins might be especially harmful. For example, red and processed meats have long been linked with a variety of chronic health issues, whereas fish generally are associated with heart-healthy benefits, especially fish that are high in omega-3 fatty acids.
A drawback of this study is the general similarity of its participants: the Nurses’ Health Study primarily collected data from white women working in health care.
“The data from the study tended to be very homogeneous in terms of demographic and socioeconomic composition,” Dr Ardisson Korat agreed, “so it will be valuable to follow up with a study in cohorts that are more diverse.”
Nevertheless, these findings are a good first step in understanding the potential connections between overall health, aging and diet — particularly protein sources — in women.
“It’s a field that is still evolving.”
So far, Dr Ardisson Korat and collaborators’ findings support the recommendation that women consume most of their protein in the form of fruits, vegetables, nuts, and seeds, although they could also consume some fish and animal protein to maintain their iron and vitamin B12 levels.
“Dietary protein intake, especially plant protein, in midlife plays an important role in the promotion of healthy aging and in maintaining positive health status at older ages,” Dr Ardisson Korat concluded.
Source:
Andres V Ardisson Korat, M Kyla Shea, Paul F Jacques, Paola Sebastini, Molin Wang, A Heather Eliassen, Walter C Willett, and Qi Sun (2024). Dietary protein intake in midlife in relation to healthy aging – results from the prospective Nurses’ Health Study cohort, American Journal of Clinical Nutrition | doi:10.1016/j.ajcnut.2023.11.010
