Wednesday, January 15, 2025

Is eating more red meat bad for your brain?

Processed red meat linked to increased risk of dementia



American Academy of Neurology




MINNEAPOLIS — People who eat more red meat, especially processed red meat like bacon, sausage and bologna, are more likely to have a higher risk of cognitive decline and dementia when compared to those who eat very little red meat, according to a study published in the January 15, 2025, online issue of Neurology®, the medical journal of the American Academy of Neurology.

“Red meat is high in saturated fat and has been shown in previous studies to increase the risk of type 2 diabetes and heart disease, which are both linked to reduced brain health,” said study author Dong Wang, MD, ScD, of Brigham and Women’s Hospital in Boston. “Our study found processed red meat may increase the risk of cognitive decline and dementia, but the good news is that it also found that replacing it with healthier alternatives, like nuts, fish and poultry, may reduce a person’s risk.”

To examine the risk of dementia, researchers included a group of 133,771 people with an average age of 49 who did not have dementia at the start of the study. They were followed up to 43 years. Of this group, 11,173 people developed dementia.

Participants completed a food diary every two to four years, listing what they ate and how often.

Researchers defined processed red meat as bacon, hot dogs, sausages, salami, bologna and other processed meat products. They defined unprocessed red meat as beef, pork, lamb and hamburger. A serving of red meat is three ounces, about the size of a deck of cards.

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

For processed red meat, they divided participants into three groups. The low group ate an average of fewer than 0.10 servings per day; the medium group ate between 0.10 and 0.24 servings per day; and the high group, 0.25 or more servings per day.

After adjusting for factors such as age, sex and other risk factors for cognitive decline, researchers found that participants in the high group had a 13% higher risk of developing dementia compared to those in the low group.

For unprocessed red meat, researchers compared people who ate an average of less than one half serving per day to people who ate one or more servings per day and did not find a difference in dementia risk.

To measure subjective cognitive decline, researchers looked at a different group of 43,966 participants with an average age of 78. Subjective cognitive decline is when a person reports memory and thinking problems before any decline is large enough to show up on standard tests.

The subjective cognitive decline group took surveys rating their own memory and thinking skills twice during the study.

After adjusting for factors such as age, sex and other risk factors for cognitive decline, researchers found that participants who ate an average of 0.25 servings 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 servings per day.

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

To measure objective cognitive function, researchers looked at a different group of 17,458 female participants with an average age of 74. Objective cognitive function is how well your brain works to remember, think and solve problems.

This group took memory and thinking tests four times during the study.

After adjusting for factors such as age, sex and other risk factors for cognitive decline, researchers found that eating higher processed red meat was associated with faster 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.

Finally, researchers found that replacing one serving per day of processed red meat with one serving per day of nuts and legumes was associated with a 19% lower risk of dementia and 1.37 fewer years of cognitive aging. Making the same substitution for fish was associated with a 28% lower risk of dementia and replacing with chicken was associated with a 16% lower risk of dementia.

“Reducing how much red meat a person eats and replacing it with other protein sources and plant-based options could be included in dietary guidelines to promote cognitive health,” said Wang. “More research is needed to assess our findings in more diverse groups.”

A limitation of the study was that it primarily looked at white health care professionals, so the results might not be the same for other race, ethnic and non-binary sex and gender populations.

The study was supported by the National Institutes of Health.

Discover more about dementia at BrainandLife.org, from the American Academy of Neurology. This resource also offers a magazine, podcast, and books that connect patients, caregivers and anyone interested in brain health with the most trusted information, straight from the world’s leading experts in brain health. Follow Brain & Life® on FacebookX, and Instagram.

The American Academy of Neurology is the leading voice in brain health. As the world’s largest association of neurologists and neuroscience professionals with more than 40,000 members, the AAN provides access to the latest news, science and research affecting neurology for patients, caregivers, physicians and professionals alike. The AAN’s mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor who specializes in the diagnosis, care and treatment of brain, spinal cord and nervous system diseases such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.

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Journal



Red meat consumption increases risk of dementia and cognitive decline



Mass General Brigham researchers found that diets high in processed meats, including bacon, hot dogs and sausage, were associated with a 13 percent higher risk of dementia in participants followed for up to 43 years



Mass General Brigham




Red meat consumption is an established risk factor for chronic conditions, including cardiovascular disease and type 2 diabetes. A new study by investigators from Mass General Brigham, Harvard T.H. Chan School of Public Health, and the Broad Institute of MIT and Harvard found that eating greater quantities of red meat, especially in processed forms, increased risk for dementia, too. Results, published online on January 15, 2025, in Neurology®, the medical journal of the American Academy of Neurology, highlight that replacing processed red meat with protein sources like nuts and legumes or fish may decrease dementia risk by approximately 20 percent.

“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,” said corresponding author Daniel Wang, MD, ScD, of the Channing Division of Network Medicine at Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system. Wang is also an associate member at the Broad Institute and an assistant professor in the Department of Nutrition at Harvard Chan School. “We hope our results encourage greater consideration of the connection between diet and brain health.”

As the U.S. population ages, dementia represents a growing challenge for patients and families. Among 133,771 individuals included in this study with an average age of 49 years at baseline, 11,173 were diagnosed with dementia up to 43 years later. Data were drawn from the Nurses’ Health Study (NHS) and Health Professionals Follow-Up Study (HPFS), which prospectively study thousands of participants’ health and lifestyles, which may influence risk of chronic diseases like dementia. The studies include decades of detailed health information, including participants’ typical diets, which they update every 2 to 4 years.

A typical serving of red meat is 3 ounces — approximately the size of a bar of soap. Those eating a daily average of one-quarter or more of a serving of processed red meats (roughly two slices of bacon, one and half slices of bologna, or a hot dog), compared to those consuming a minimal amount, (less than one-tenth a serving each day) had a 13 percent higher risk of developing dementia, adjusting for numerous clinical, demographic and lifestyle factors such as socioeconomic status and family history of dementia.

The researchers measured objective cognitive function using standard cognitive assessments. They found that this measure was also worse among those with greater processed meat consumption, with cognitive aging accelerated by approximately 1.6 years per average daily serving.

The researchers also examined self-reported subjective cognitive decline (SCD), which may precede markers of cognitive decline on standard evaluations. A greater risk of SCD was associated with consuming either processed or unprocessed meats (like beef, pork and hamburger). SCD risk increased by 14 percent for those eating one-quarter or more servings of processed meat daily compared to the minimal-consumption group, and by 16 percent for those eating one or more daily servings of unprocessed meat compared to those eating less than half a serving.

The researchers are continuing to explore factors linking red meat with dementia risk, especially those involving the gut microbiome. Trimethylamine N-oxide (TMAO), a product of the bacteria-mediated breakdown of meat, may increase cognitive dysfunction due to its effects on the aggregation of amyloid and tau, proteins involved in Alzheimer’s disease, but research is limited. The saturated fat and salt content of red meat may also impair brain cells’ health.

“Large, long-term cohort studies are essential for investigating conditions like dementia, which can develop over decades,” Wang said. “We are continuing to piece together this story to understand the mechanisms causing dementia and cognitive decline.”

Authorship: In addition to Wang, Mass General Brigham authors include first author Yuhan Li, Yuxi Liu, Danyue Dong, Jae Hee Kang, Molin Wang, Heather Eliassen, Walter C. Willett, and Meir J. Stampfer. Additional authors include Yanping Li and Xiao Gu.

Disclosures: None.

Funding: This study was supported by the National Institutes of Health (R01AG077489, RF1AG083764, R00DK119412, R01NR019992, and P30DK046200).

Paper cited: Li Y et al. “Long-Term Intake of Red Meat in Relation to Risk of Dementia and Cognitive Function in US Adults ”Neurology DOI: 10.1212/WNL.0000000000210286

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About Mass General Brigham

Mass General Brigham is an integrated academic health care system, uniting great minds to solve the hardest problems in medicine for our communities and the world. Mass General Brigham connects a full continuum of care across a system of academic medical centers, community and specialty hospitals, a health insurance plan, physician networks, community health centers, home care, and long-term care services. Mass General Brigham is a nonprofit organization committed to patient care, research, teaching, and service to the community. In addition, Mass General Brigham is one of the nation’s leading biomedical research organizations with several Harvard Medical School teaching hospitals. For more information, please visit massgeneralbrigham.org.

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