Red meat blamed for increased cognitive decline in study

NEW YORK, Jan. 15 (UPI) -- Eating greater amounts of red meat -- especially processed bacon, sausage and bologna -- increases the likelihood of cognitive decline and dementia, a new study suggests.

The study, funded by the National Institutes of Health, was published Wednesday in Neurology, the journal of the American Academy of Neurology.

The study adds to the established knowledge that people who consume red meat face a higher risk of death from heart disease, stroke or diabetes. Processed meats also increase the risk of death from them.

The high saturated fat content in red meat could contribute to aged-related cognitive decline by impairing cholesterol metabolism and inducing insulin resistance, the researchers theorized, so making dietary changes may offer significant benefits.

To preserve cognitive health, investigators recommended switching to healthier protein sources -- fish, poultry, eggs, low-fat dairy, nuts and legumes -- as well as plant-based options.

"We undertook this study to explore the potential link between red meat consumption and cognitive decline and dementia risk," the study's first author, Yuhan Li, told UPI.

"Previous research on this topic has shown inconsistent findings, and understanding this relationship is crucial given the increasing prevalence of dementia and the lack of a cure," said Li, a research assistant at the Channing Division of Network Medicine at Brigham and Women's Hospital in Boston.

To evaluate dementia risk, researchers included 133,771 people averaging 49 years old who did not have the condition at the study's outset. A total of 11,173 people developed dementia during the follow-up spanning up to 43 years.

In completing a food questionnaire every two to four years, participants recorded what they consumed and how frequently.

Red meat consisted of bacon, hot dogs, sausages, salami, bologna and other processed meat products. Beef, pork, lamb and hamburger were considered unprocessed red meat, researchers said.

A serving was equal to three ounces of red meat -- about the size of a deck of cards.

Researchers calculated how much red meat participants consumed on average per day.

For processed red meat, they stratified participants into three groups. Consumption averaged fewer than 0.10 serving per day in the low group; between 0.10 and 0.24 serving per day in the medium group; and 0.25 or more servings per day in the high group.

The high group had a 13% higher risk of developing dementia compared to the low group, after researchers adjusted for variables such as age, sex and other risk factors for cognitive decline.

For unprocessed red meat, researchers compared people who ate an average of less than one-half serving per day to those who consumed one or more servings per day. They didn't observe a difference in dementia risk.

To measure subjective cognitive decline, researchers evaluated a different group of 43,966 participants with an average age of 78. Subjective cognitive decline occurs when a person notes memory and thinking problems before any decline is significant enough to register on standard tests.

After adjusting for variables such as age, sex and other risk factors for cognitive decline, researchers noted that participants who consumed an average of 0.25 serving or more per day of processed red meat had a 14% higher risk of subjective cognitive decline compared to those who ate an average of fewer than 0.10 serving per day.

They also found people who ingested one or more servings of unprocessed red meat per day had a 16% higher risk of subjective cognitive decline compared to those who had less than a half-serving per day.

To measure objective cognitive function, researchers turned to another group of 17,458 female participants with an average age of 74. Objective cognitive function represents how well the brain functions to remember, think and solve problems.

After adjusting for age, sex and other risk factors for cognitive decline, they found that eating higher processed red meat was linked to swifter brain aging in global cognition with 1.61 years with each additional serving per day and in verbal memory with 1.69 years with each additional serving per day.

Researchers also noted that substituting one serving per day of processed red meat with one serving of nuts and legumes was associated with a 19% decreased risk of dementia and 1.37 fewer years of cognitive aging.

Making the same replacement for fish was linked to a 28% lower risk of dementia, while substitution with chicken was associated with a 16% decreased risk.

However, the researchers acknowledged a limitation -- that their study mainly evaluated White healthcare professionals, so the results may not be the same for other race, ethnic and non-binary sex and gender populations.

Other experts praised the researchers for examining the connection between red meat and cognitive decline and dementia in a study involving more than 100,000 participants.

"This study adds to the growing body of evidence that the lifestyle choices we make impact our brain health," said Dr. Judith Heidebrink, a research professor of Alzheimer's disease at the University of Michigan in Ann Arbor. She was not involved in the study.

"This study provides yet another example that a healthier diet, with fewer processed foods, is associated with a lower risk of cognitive decline," Heidebrink said.

However, researchers didn't account for food preparation such as frying, said Dr. Karima Benameur, an associate professor of neurology at Emory University in Atlanta.

"There is evidence that the method of cooking is just as important in mitigating risks," Benameur said.

Limiting portions of red meat to less than one serving per day also can minimize potential risks, said Theresa Gentile, a spokesperson for the Academy of Nutrition and Dietetics and coordinator of discharge planning for home enteral nutrition at Maimonides Medical Center in Brooklyn, N.Y.

Overall, Gentile added, the study "sends the clear message that what we eat can profoundly impact not just our physical health, but also our brain's longevity and function."