Based on outcomes from nearly 130,000 adults, the results contribute to mounting research suggesting that red meat, which is high in saturated fat, can be bad for the brain.
“Our findings provide further evidence that higher red meat consumption, especially processed red meat consumption, is associated with higher risk of cognitive decline and dementia risk,” says Yuhan Li, PhD, an assistant professor of anesthesia at Brigham and Women’s, a teaching hospital affiliated with Harvard Medical School in Boston.
“Additionally, our results highlight the benefits of replacing processed red meat with healthier alternatives, such as nuts and legumes, contributing to the development of actionable diet guidance for improving dietary patterns to support cognitive health.”
Higher Red Meat Consumption Tied to Greater Dementia Risk
To measure the risk of dementia from eating red meat, Dr. Li and his team followed about 134,000 individuals for up to 43 years. Participants were an average age of 49 and did not have dementia when the research began. They completed a food diary every two to four years, listing what they ate and how often. By the end of the study, 11,173 (8.3 percent) had developed dementia.
Processed red meats were defined as products such as bacon, hot dogs, sausages, salami, and bologna, while unprocessed red meats were defined as beef, pork, lamb, and hamburger. A serving was considered to be 3 ounces — about the size of a pack of cards.
For the analysis of processed meat, participants were separated into three groups. On average, the low-consumption group ate less than one-tenth of a serving per day (or about three servings per month), the medium group ate one-tenth to less than one-quarter serving per day, and the high group ate one-quarter serving or more per day (or about two servings at least per week).
The findings showed that those who were eating the most processed meat had 13 percent greater odds of developing dementia compared with those in the low consumption group.
To evaluate dementia risk in relation to unprocessed red meat, researchers compared individuals who ate an average of less than one-half serving per day with those who ate one or more servings per day. They did not find a difference in dementia risk.
Evaluating Cognitive Decline
To gauge cognitive decline, scientists analyzed subjective measures based on surveys in which participants rated their own memory and thinking skills twice during the study. They also weighed objective measures based on memory, thinking, and problem-solving tests given four times during the study.
In the subjective group, which included about 44,000 participants who were an average age of 78, those who ate an average of at least one-quarter serving of processed red meat per day had a 14 percent higher risk of cognitive decline compared with those who ate less than one-tenth of a serving.
Researchers also highlighted that those who ate one or more servings of unprocessed red meat per day had a 16 percent higher risk of subjective cognitive decline compared with those who ate less than one-half of a serving per day.
From the objective group analysis, which looked at about 17,000 female participants with an average age of 74, study authors found that eating more processed red meat was associated with faster brain aging, with the brain being 1.61 years “older” with each additional serving per day.
Why Is Processed Meat Bad for the Brain?
The high saturated fat content in red meats — whether processed or unprocessed — may be a primary contributor to mental decline, according to Li.
For Yuko Hara, PhD, director of aging and Alzheimer’s prevention at the Alzheimer’s Drug Discovery Foundation, the difference between processed and unprocessed red meats may be due to ingredients added to processed products.
Heather Snyder, PhD, the senior vice president of medical and scientific relations at the Alzheimer’s Association, confirms that it’s the ultraprocessing that may be especially bad for the brain.
Swapping Red Meat for Healthier Alternatives
The study authors also looked at the data to see how people might lower risk, and they found that replacing one serving per day of processed red meat with one serving per day of nuts and beans was associated with a 19 percent lower risk of dementia and 1.37 fewer years of cognitive aging.
Making the same substitution for fish was linked to a 28 percent lower risk of dementia, and replacing it with chicken was linked with a 16 percent lower risk of dementia.
Rebecca Beaudoin, RDN, a nutrition therapist with Nebraska Medicine in Omaha, especially stresses the value of eating more plants in your diet.
“We know that increasing the consumption of plants is associated with greater health,” says Beaudoin. “As we increase our consumption of fruits, veggies, beans, and whole grains, we increase both our fiber, which is anti-inflammatory, and phytochemicals, natural substances that can help protect against cell damage.”