A preliminary new study has shown that the risk of developing dementia increased by 14% when individuals consume about one ounce of processed red meat daily - which equates to just under two servings of three ounces a week - compared to those who consumed about three servings only per month.

However, the risk of developing dementia decreased by 20% for individuals who replaced that small daily serving of processed red meat with a daily serving of nuts and legumes.

Processed red meats such as bacon, sausages, hot dogs, and deli meats often contain higher levels of sodium, nitrates, and saturated fats. Studies have shown that consuming larger amounts of these meats is closely associated with the development of colon cancer and other types of cancer, type 2 diabetes, heart disease, and strokes.

Dr. Walter Willett, professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health in Boston, said, "There is a lot we can do to reduce the risk of dementia, starting with well-known measures to reduce the risk of cardiovascular diseases."

Willett stated in an email, "There are still aspects of this that need to be understood in more detail. For example, certain foods seem to be particularly important to include, and we would like to understand the specific active ingredients, but we do not need to wait for all the details to take action."

Dr. David Katz, a preventive medicine and lifestyle expert who did not participate in the study, noted that the study was observational and can show only correlation, not necessarily cause and effect.

He explained in an email, "However, it is very likely that the correlations are causal, as the major risk factors for Alzheimer’s disease and cognitive decline are the same risk factors for cardiovascular diseases, with which processed meat consumption is closely tied." Katz is the founder of the non-profit True Health Initiative, a global coalition of experts dedicated to evidence-based lifestyle medicine.

Each additional meal of processed red meat increases the risks

A summary of the study, currently under review for publication, was presented on Wednesday at the 2024 Alzheimer's Association International Conference in Philadelphia.

For over three decades, researchers have collected dietary data from more than 130,000 participants in the Nurses’ Health Study, one of the largest investigations into the risk factors for major chronic diseases in women, and the accompanying Health Professionals Follow-Up Study, which looked at the same risk factors in men.

Men and women were asked how often they had a serving of processed red meat, which could be two slices of bacon, one hot dog, or two small links of sausage or kielbasa, salami, bologna, or other processed meat sandwiches.

Participants in the study were also asked how often they consumed nuts and legumes, such as a tablespoon of peanut butter; one ounce of peanuts or walnuts or other nuts; an eight-ounce cup of soy milk; half a cup of green beans or lentils or beans or peas or white beans; or a typical serving of tofu or soy protein weighing three ounces.

Dr. Maria Carrillo, Chief Science Officer at the Alzheimer's Association, which did not participate in the study, said, "These are anti-inflammatory foods, so you can imagine that they have many benefits in addition to reducing processed meats that contain toxins, nitrates, and sodium that are not good for you."

In addition to the 14% cognitive decline associated with consuming approximately two servings a week of processed red meat, the study found an increase in risk associated with each additional serving.

According to the study, each additional daily serving added 1.61 more years of cognitive aging for global cognition and 1.69 more years of cognitive aging for verbal memory.

Global cognition provides a broad overview of cognitive function. Johan Lee, a research associate at the Channing Division of Network Medicine at Brigham and Women's Hospital in Boston, said in an email, "This can help capture the overall impact of dietary and lifestyle factors on cognitive health."

Lee, who conducted the study while studying at Harvard T.H. Chan School of Public Health, said, "Verbal memory refers to memory for information presented verbally. It is an important indicator of Alzheimer’s disease."

Tips for reducing processed meats and red meats in your diet

Simply substituting animal products for plant-based ones does not automatically lead to a healthy diet. As the study illustrates, the outcome may depend on the types of foods you are consuming instead.

Instead of focusing on the specific benefits and drawbacks of certain heart-healthy foods, try to concentrate on an overall eating pattern, said Christopher Gardner, professor of medicine research at Stanford’s Prevention Research Center in California who is not involved in the study.

Gardner told CNN in a previous interview, "When it comes to one heart-healthy nutrient, you might simply inject that nutrient into a food and claim it’s healthy food, which it isn't."

"Or if there’s a superfood like chia seeds, you can really eat something unhealthy and sprinkle chia seeds on it and say, 'Oh, I’m protected now.' No, it has to be part of an overall healthy pattern of foods."

Experts say award-winning meal plans like the Mediterranean diet and the Dietary Approaches to Stop Hypertension (DASH) are more of a lifestyle than a "diet." Both focus on simple, plant-based cooking, with most meals emphasizing fruits, vegetables, whole grains, beans, nuts, and seeds.

Red meat consumption is limited. Instead, diets emphasize the intake of healthy oily fish, rich in omega-3 fatty acids beneficial for the brain, alongside lean meats like poultry and pork.

According to experts, one easy way to start a low-meat diet is to cook one meal each week based on beans, whole grains, and vegetables, using herbs and spices to add more flavor. Once one night a week is easy, add two nights, and build your meatless meals from there.

When incorporating meat, use small pieces of chicken or slices of lean meat to flavor a vegetable dish, like stir-fry.

Experts say another easy step is to swap refined grains for whole grains. Choose whole grain bread and pasta and replace white rice with brown rice.