As people age, the risk of developing diseases like heart disease, diabetes, and dementia rises. Often, these health complications are considered inevitable downsides of aging.

However, new research and a related literature review throw a wrench in this conventional wisdom. Together, the findings suggest eating a plant-heavy diet can significantly delay the aging process, disease, and death.

The most recent study, published Monday in the JAMA Internal Medicine, analyzed the eating patterns and health outcomes of over 400,000 people over 16 years. The team found higher plant protein intake can cut the risk of disease and death by more than 12 percent.

The research also suggests that beneficial dietary shifts don’t have to be dramatic. Replacing just three percent of energy from animal protein with plant protein was associated with 10 percent decreased overall mortality in both men and women.

These striking findings add to a long list of other studies summarized in a related editorial, published Monday in the Journal of the American College of Nutrition. In the editorial, researchers suggest plant-based diets can reduce the risk of diseases such as type 2 diabetes, cancer, and heart disease by almost 50 percent. In some studies, it reduced cardiometabolic-related deaths in the United States by half. Editorial co-author Hana Kahleova, director of clinical research at the Physicians Committee for Responsible Medicine, argues that, on top of reducing disease, plant-based diets present “huge benefits for the global community.” “By eating a healthful diet, we can not only add years to our lives, but life to our years,” Kahleova says. “By staying healthy as we age, we will improve our quality of life and enjoy life more with the people we love.”

Food Science

Until now, researchers hadn’t pinned down the exact health impacts of consuming plant-protein versus animal protein. To answer that hotly debated question, researchers leveraged data from the NIH-AARP Diet and Health Study, a large prospective cohort of more than 400,000 participants with more than 77,000 deaths. The study originally kicked off in 1995, recruiting 617,119 participants between age 50 to 71 from six states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and two metropolitan areas (Atlanta and Detroit). Participants filled out a series of detailed questionnaires documenting their demographics and lifestyle characteristics. The group also completed the National Cancer Institute Diet History Questionnaire (DHQ) which tracked how much people consumed 124 different foods.

Approximately 40 percent of the group’s daily dietary protein was from plant sources, and 60 percent was animal protein (including 19 percent dairy protein). These diet breakdowns mirror the habits of the United States population, the researchers say. The team then analyzed who died, as well as their causes of death, over the next 16 years.

The results were striking: Across the board, greater intake of plant protein was significantly associated with lower overall mortality and cardiovascular disease mortality, independent of several other risk factors.

Specifically, swapping out 3 percent of animal protein with plant protein was associated with a 10 percent lower mortality risk in both men and women. Making this swap was also linked to an 11 percent lower risk of dying of cardiovascular disease in men, and a 12 percent lower risk in women. These protective effects were primarily associated with substituting eggs and red meat for plants.

Based on these findings, the authors say modifying the choice of protein sources may promote health and longevity. The authors also suggest public recommendations should reflect this research.

Diet and Disease

On top of this recent study, Kahleova and her co-authors rounded up other studies exploring how plant-based diets influence health and aging. The Physicians Committee for Responsible Medicine, a non-profit research and advocacy organization that tends to favor plant-based eating, authored and funded their editorial.

The team found a plant-based diet heavy in fruits, vegetables, grains, and legumes can:

• Reduce the risk of developing metabolic syndrome and type 2 diabetes by about 50 percent.
• Reduce the risk of coronary heart disease events by an estimated 40 percent.
• Reduce the risk of cerebral vascular disease events by 29 percent.
• Reduce the risk of developing Alzheimer’s disease by more than 50 percent.

These findings point to clear changes in the way people eat. The researchers say: opt for more plants and less meat.

“Adopting a healthful diet and lifestyle is a powerful tool which may delay the aging process, decrease age-associated co-morbidities and mortality, and increase life expectancy,” the researchers write. “This strategy represents the most cost-effective approach, and should be incorporated in everyday practice.”

However, transforming your diet isn’t always simple. Access to nutrient-rich foods isn’t equally accessible or affordable across communities. (Although some research suggests plant-based diets can come with an annual savings of 750 U.S. dollars.)

In light of the Covid-19 pandemic, which has put health disparities in stark clarity, Kahleova says the time to move toward a healthful, plant-based diet is now. “More than ever, it’s important that we keep our bodies as healthy as we possibly can,” Kahleova says. The researcher notes that a healthful, plant-based diet can help manage many of the world’s leading causes of death — chronic conditions that make Covid-19 more severe.

“It’s one more reason to make sure we’re adding more healthy, plant-based foods to our plates,” Kahleova explains. And there are economic advantages too. By 2050, the population of adults 60 and up is predicted to double from 841 million to 2 billion. The ballooning older set will strain the health system.

“To tackle the challenges of an aging population, we have no choice,” Kahleova and her team write. “We must address the major lifestyle risk factors, such as smoking, lack of physical activity, and, most of all, poor diet.”