Nuts to you: Diets rich in plant protein could help women stay healthy

Women who eat more plant-based protein develop fewer chronic diseases and are generally healthier later in life, according to self-reported data from more than 48,000 women in the US. They were shown to develop fewer chronic diseases and be more likely to be healthier overall as they get older, according to researchers at the Human Nutrition Research Center on Aging at Tufts University in Massachusetts. 

Protein intake has always played an important role in maintaining the health status of older adults, but few epidemiologic studies have examined midlife protein intake in relation to healthy aging. 

The study, just published in The American Journal of Clinical Nutrition under the title “Dietary protein intake in midlife in relation to healthy aging – results from the prospective Nurses’ Health Study [NHS] cohort,” showed significantly fewer cases of heart disease, cancer, and diabetes, and cognitive and mental health decline, in those who included more protein in their diets from sources such as fruits, vegetables, bread, beans, legumes, and pasta, compared to those who ate less.

A total of 3,721 (7.6%) NHS participants met the team’s healthy aging definition. Protein intake was significantly associated with higher odds of healthy aging.

“Consuming protein in midlife was linked to promoting good health in older adulthood,” said Andres Ardisson Korat, the study’s lead author “We also found that the source of protein matters. 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.”

Findings were derived from the seminal Harvard-based Nurses’ Health Study, which followed female healthcare professionals from 1984 to 2016. The women were between the ages of 38 and 59 in 1984 and deemed to be in good physical and mental health at the start of the study.

The meta-analysis examined thousands of surveys collected every four years from 1984 to 2016 on how frequently people ate certain foods to pinpoint dietary protein and its effects on healthy aging. They calculated protein intake by multiplying the number of times 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 food items.

The team then compared the diets of women who didn’t develop 11 chronic diseases or lose a lot of physical function or mental health, with the diets of those who did. Women who ate more plant-based protein, which in 1984 was defined 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. Those who consumed more animal protein such as beef, chicken, milk, fish/seafood, and cheese, however, were six percent 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,” said Ardisson Korat.

Animal protein was modestly tied with fewer physical limitations in older age, but plant protein had a stronger, more consistent correlation across all observed models, and was more closely linked with sound mental health later in life. For heart disease in particular, higher plant protein consumption came with lower levels of LDL (“bad”) cholesterol, blood pressure, and insulin sensitivity, while higher animal protein intake was tied to higher levels, along with increased insulin-like growth factor that has been detected in multiple cancers.

Dairy protein alone (mainly milk, cheese, pizza, yogurt, and ice cream) was not significantly associated with better health status in older adulthood.

The team acknowledged that the benefits of plant protein might derive from components in plant-based food, rather than the protein compared to animal foods, plants contain a higher proportion of dietary fiber, micronutrients, and beneficial compounds called polyphenols that are present in plants, rather than only protein.

The team’s findings so far support the recommendation that women eat most of their protein in the form of fruits, vegetables, nuts, and seeds, although they should also consume some fish and animal protein for their iron and vitamin B12 content.