Eating more plant protein may promote healthy aging in women

The researchers analyzed self-reported data from the Harvard-based Nurses’ Health Study, which followed 48,000 female healthcare professionals from 1984 to 2016.

To assess dietary intake, they examined thousands of surveys that the participants completed every 4 years between 1984 and 2016. Participants had to record how often they ate certain foods, from which the researchers calculated protein intake by multiplying how often each food item was consumed by its protein content.

They then used the Harvard University Food Composition Database to calculate the total protein consumed.

The participants filled in a health questionnaire in 2014 and at the end of the study in 2016. In 2016, they also filled out a questionnaire about their mental health. In 2016, they also filled out questionnaires about their mental health and level of physical function.

• cancer (except for non-melanoma skin cancer)
• type 2 diabetes
• myocardial infarction
• coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty
• congestive heart failure
• stroke
• kidney failure
• chronic obstructive pulmonary disease
• Parkinson’s disease
• multiple sclerosis
• amyotrophic lateral sclerosis

They compared the diets of those who did not report any chronic disease with the diets of those who reported at least one of the diseases listed.

Although eating protein in any form in midlife was associated with healthier aging, plant protein seemed to have a greater beneficial effect, as Andres Ardisson Korat, a scientist at the HNRCA and lead author of the study, explained to MNT.

“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,” Korat said.

In 1984, plant-based protein was defined as protein from:

The researchers found that women who got more protein from these items were 46% more likely to remain healthy into older age.

By contrast, those who obtained most of their protein from animal sources — meat, milk, fish and other seafood, and cheese — were 6% less likely to be healthy as they got older.

Costa suggested how protein might affect health as we age.

“The impact of protein intake on healthy aging is influenced by various intricate and interrelated factors that we have yet to fully comprehend,” she said.

“As suggested by the study authors, preliminary evidence indicates that dietary protein and physical activity stimulate the activation of the mammalian target of the rapamycin complex 1 (mTORC1) signaling pathway, which seems to decline with age, boosting muscle protein synthesis and improving physical function in older adults,” Costa noted.

The authors do suggest that the benefits observed in those who had more plant protein in their diets might be, in part, due to other dietary components of plants, such as dietary fiber, micronutrients (vitamins and minerals), and polyphenols — antioxidants that are widely believed to be beneficial to human health.

“This [healthy aging effect] comes as no surprise as these components have been linked to a host of health benefits, including reduced inflammation and oxidative stress, improved cardiovascular health and insulin sensitivity, and promotion of gut microbiome diversity — all factors that contribute to healthy aging,” Costa said.

“A diet rich in plant-derived foods has been associated with lower rates of chronic diseases, such as type 2 diabetes, cardiovascular disease, and certain cancers. While protein is an essential nutrient for maintaining health and preventing age-related declines, the evidence suggests that a varied diet with plenty of plant-based protein sources, specifically, is the most beneficial for promoting healthy aging.”

— Kelsey Costa, registered dietitian nutritionist

The authors note that the study did have limitations — the cohort was predominantly white and female, so the findings may not apply to other populations. In addition, all the data was taken from self-reported questionnaires, with some time lag, so there may be some bias in the data.

They also acknowledge that they “cannot discount the contributions of other components of those foods that contributed to plant protein intake.”

However, it was a large cohort, and the participants were observed over a long time period.

Costa advised that everyone can benefit from increasing their intake of plant foods.

“For healthy aging, consider adopting a predominantly plant-based eating regimen, such as the Green Mediterranean diet or any other balanced, plant-focused diet. Minimize the intake of animal-based foods while emphasizing the consumption of wholesome, plant-derived foods.”

“However,” she warned, “don’t rely on ultra-processed ‘plant-based’ food products that contain minimal whole foods and are high in sodium, refined oils, and added sugars.”

“Instead, opt for predominantly low-processed versions of whole grains, legumes, fruits, vegetables, nuts, and seeds, and include some healthy processed foods like tofu, precooked lentils, or chickpea pasta,” she advised.

“Include nutrient-rich berries and dark, leafy greens in your daily meals, along with omega-3-rich foods like flaxseeds and walnuts. These foods are associated with reduced inflammation and improved cognitive function, important aspects of healthy aging.”