Want to Keep Your Brain Sharp? New Research Suggests a Helpful Food Swap

Swapping bacon for beans might benefit your brain. A new Harvard study suggests replacing just one serving of processed meat with nuts or beans is linked to a 19% lower risk of dementia.

Published in the journal Neurology, the study followed more than 133,000 adults over several decades. All were free of dementia at the start. Researchers tracked their diets using detailed questionnaires given every two to four years and monitored changes in their cognitive health over time.

After adjusting for age, sex, and other risk factors, they found that people who ate more red meat—especially processed varieties like bacon, sausage, and deli meats—were more likely to experience cognitive decline and develop dementia. Just a quarter serving of processed meat a day (about two slices of bacon) was linked to a 13% higher risk of dementia and a 14% higher risk of cognitive decline later in life. People who ate the most processed meat also showed faster declines in thinking and memory, with an extra 1.6 years of cognitive aging.

These rates took into account factors including socioeconomic status and a family history of dementia.

Unprocessed meats weren’t off the hook, either. Eating a full serving of steak, lamb, or other unprocessed meat each day was associated with a 16% higher risk of subjective cognitive decline (the perception of one’s own memory worsening).

The good news? Swapping nutrient-rich nuts and legumes for one daily serving of processed red meats was associated not only with a 19% lower risk of dementia but also with a 21% lower risk of subjective cognitive decline and a slower rate of cognitive aging.

Several biological factors may explain the connections. Previous research demonstrates that consuming red meat boosts the body's concentration of trimethylamine N-oxide (TMAO), a harmful compound produced by gut bacteria. Elevated TMAO levels appear to increase neuroinflammation and damage the blood-brain barrier, potentially contributing to cognitive impairment.

Additionally, studies have linked meat-heavy diets with cardiovascular diseases. These conditions may contribute to an increased risk of cognitive decline and dementia by reducing blood flow to the brain, changing brain structure, triggering inflammation, and promoting the buildup of harmful proteins.

“Dietary guidelines tend to focus on reducing risks of chronic conditions like heart disease and diabetes, while cognitive health is less frequently discussed, despite being linked to these diseases,” says corresponding author Daniel Wang, M.D., Sc.D., of the Channing Division of Network Medicine at Brigham and Women’s Hospital, a founding member of the Mass General Brigham health care system. Wang says he hopes that the results will “encourage greater consideration of the connection between diet and brain health.”

The Harvard study doesn’t prove that red and processed meat cause dementia; other lifestyle factors may have played a role, and the study’s population was unique in that all participants were health care professionals. However, the new research adds to growing evidence that what we eat plays a big role in how our brains age—and that a plant-forward diet may offer protection against cognitive decline.

To learn more about a whole-food, plant-based diet, visit our Plant-Based Primer. For meal-planning support, check out Forks Meal Planner, FOK’s easy weekly meal-planning tool to keep you on a healthy plant-based path.