Are processed meats linked to an increased dementia risk?

Last Updated : 03 February 2025

Recent news stories have reported that people who eat a lot of processed meat, such as bacon, pepperoni, and sausages, face a higher risk of cognitive decline and dementia. Most dietary guidelines already recommend eating little processed meat, if any. This is because they’re often high in salt, energy, fat, cholesterol, and other compounds formed during processing which can harm health. Does this study on cognition and dementia add another reason to limit processed meats? Here are few things to keep in mind when reading the headlines.

The study behind the headlines

While there is consistent scientific evidence linking processed meats with health risks, such as colorectal cancer, cardiovascular diseases, and type 2 diabetes, previous studies on neurocognitive disorders have shown mixed results. Therefore, this study sought to clarify these associations by exploring the relationship between processed and unprocessed red meat consumption and the risk of developing dementia and cognitive decline in adults in the United States.¹

The study included data from two large groups of people: the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS). The NHS started in 1976 with 121,700 female nurses aged 30 to 55, while the HPFS began in 1986 with 51,529 male health professionals aged 40 to 75.

Participants were asked about their diets every 2 to 4 years to assess how much red meat and unprocessed red meat they ate, with 9 frequency options ranging from “never or less than once per month” to “6+ per day.” They were then tracked over the years to see who developed dementia (the main outcome of interest) or reported cognitive decline.

Which meats are considered processed?

Processed meats are those which have undergone additional treatment from their fresh form, most often to improve preservation. They included salted, cured, fermented or smoked meat products such as bacon, hot dogs, sausages, kielbasa, salami, bologna, and other processed meat products. Unprocessed red meats include fresh beef, pork, and lamb.

Key findings :

Participants who ate at least 0.25 servings per day (about two servings per week) of processed red meat had a 13% higher risk of developing dementia compared to those consuming less than 0.10 servings per day. One serving of processed meat is equal to two slices of bacon, one hot dog, two small links (or about 60 grams) of sausage or kielbasa. Eating this amount of processed red meat was also associated with an accelerated decline in cognitive function, equivalent to an additional 0.82 years of cognitive aging in global cognition and 0.85 years in verbal memory.

What about unprocessed red meat? Interestingly, this group did not show a clear link to dementia risk overall. However, when researchers looked at genetic differences, they found that the relationship was stronger for people who do not carry the APOE e4 allele, a gene known to increase the risk of Alzheimer’s disease, compared to people who do carry the APOE e4 allele. This suggests that for individuals without the APOE e4 allele, eating unprocessed red meat may have a greater impact on their dementia risk than for those with the gene. While unprocessed red meat was not significantly associated with objective measures of cognitive function, participants who ate at least one serving per day had a 16% higher risk of subjective cognitive decline, meaning they were more likely to perceive a worsening of their own memory and thinking abilities.

The findings also suggest that dietary changes could help mitigate dementia risk. Replacing one daily serving of processed red meat with other protein sources was associated with substantial benefits: substituting with low-fat dairy lowered dementia risk by 13%, poultry by 16%, nuts and legumes by 19%, eggs by 23%, and fish by 28%.

What to keep in mind when reading the study’s conclusions?

• The study is observational and, therefore, cannot prove that people who eat processed meat have a higher risk of dementia.

The study suggests that eating at least 0.25 servings of processed red meat per day is linked to a higher dementia risk. However, it’s important to remember that correlation doesn’t imply causation: the study doesn’t conclude that eating processed red meat causes these conditions.

Observational studies , such as this one, look for patterns between variables (in this case, between how much processed red meat people ate and dementia risk) but they cannot determine whether one causes the other. For instance, people who ate processed red meat may already be at a higher risk of dementia for reasons unrelated to their meat consumption. These could include lifestyle factors like stress, sleep quality, or other dietary habits that might affect cognitive health but were not measured in the study.

Imagine observing that people who carry umbrellas are more likely to be wet. This doesn’t mean umbrellas cause wetness, it’s the rain that links the two. Similarly, while this study suggests a link between processed red meat and dementia, it doesn’t prove that processed red meat directly affects dementia. Understanding this distinction is critical in nutritional science.

• The assessment of red meat intake and dementia was both self-reported.

Participants reported their own red meat consumption, which can lead to something called ‘recall bias.’ Recall bias happens when participants have trouble remembering their past eating habits. If someone has early signs of cognitive decline, they might remember their diet differently than someone without such issues. This could skew the results, making it seem like red meat intake is more or less harmful than it actually is.

In this case, this is a minor limitation, as the researchers conducted a special analysis to check if recall bias was a problem by looking at data from before participants started showing signs of dementia. The results from these analyses were similar to the main findings between processed red meat consumption and dementia, suggesting that recall bias was not a major issue.

The study also relied on participants to self-report their health conditions, including dementia, which can sometimes lead to misclassification if cases of dementia are not accurately reported. However, because the participants were health professionals, they were more likely to provide more reliable health information compared to the general public, reducing the risk of reporting errors.

• The study only considered a specific group of US participants and may not be representative of other populations.

This was a large study, but it included mostly middle-aged adults (average age 48.9 years) of predominantly White ethnicity from the US. Other populations and ethnic groups, with different health, lifestyle and genetic characteristics may have a different disease risk. This limitation is acknowledged by the authors.

• The decline in cognitive performance observed in those eating more processed red meat is small.

Eating at least 0.25 servings of processed meat per day compared to consuming less than 0.10 servings per day was associated with a decline in cognitive function, equivalent to an additional 0.82 years of cognitive aging in global cognition and 0.85 years in verbal memory, In practical terms, this means that someone who is 70 years old and regularly consumes processed red meat at this level may have brain function comparable to that of a 71-year-old. This is a very small relative decline in cognitive performance.

Why should we limit our processed red meat intake?

• Processed red meats often contain high levels of saturated fats and sodium. Saturated fat can raise our cholesterol levels which can, subsequently, damage brain cells and the protective covering around nerves, leading to memory and thinking problems. Diets high in saturated fats may also lower certain proteins that help brain cells connect and function properly, potentially leading to cognitive decline. High sodium levels, on the other hand, can reduce blood flow to the brain, potentially leading to vascular dementia.
• Eating a lot of red meat may make it harder for the body to use insulin properly. Insulin is also involved in clearing harmful proteins from the brain. Therefore, this could lead to the buildup of those proteins, which are linked to Alzheimer’s disease. Processed meats often contain harmful chemicals like nitrites and N-nitroso compounds, which may damage DNA and increase oxidative stress in the body, both of which can contribute to cognitive decline and the development of dementia. Red meat, including processed meats, contains a substance called L-carnitine, which our body can use to produce another compound called TMAO. TMAO is linked to brain damage and reduced flexibility in brain connections, influencing cognitive function.
• Beyond neurocognitive disorders, leading health authorities, such as the World Cancer Research Fund, recommend limiting red meat consumption to no more than three portions per week (350–500g cooked weight) and consuming very little, if any, processed meat to lower the risk of colorectal cancer. Strong evidence links processed meat to colorectal cancer, while red meat is classified as a probable cause. Cooking methods like grilling and barbecuing can further elevate cancer risk by producing cancer-causing compounds. Additionally, lower consumption of red and processed meat is associated with reduced risks of cardiovascular disease, type 2 diabetes, and overall mortality.²

References

1.  Li, Y., Li, Y., Gu, X., Liu, Y., Dong, D., Kang, J. H., ... & Wang, D. (2025). Long-term intake of red meat in relation to dementia risk and cognitive function in US adults. Neurology, 104(3), e210286.
2. World Cancer Research Fund/American Institute for Cancer Research. Continuous Update Project Expert Report 2018. Meat, fish and dairy products and the risk of cancer. Available at dietandcancerreport.org