Eating as little as one or two slices of deli meat each day was associated with a substantially higher risk of dementia in a new review examining ultra-processed foods and brain health. Researchers cautioned that the findings show an association, not direct causation.

The review, published in the August 2026 issue of Annual Review of Nutrition, assessed dozens of human and animal studies. The work was conducted by an international team of 27 researchers investigating whether diets rich in ultra-processed foods may contribute to brain aging over time.

One study included in the review involved nearly 500,000 people in the United Kingdom. Each additional 25 grams of processed meat consumed daily corresponded with a 44% higher risk of all cause dementia and a 52% higher risk of Alzheimer's.

Twenty five grams is roughly equivalent to one or two slices of deli meat, depending on how thickly the meat is sliced. Processed meats examined in the research included deli turkey, ham, salami, bacon, hot dogs and sausages.

Ultra-processed foods also include sugary beverages, packaged snacks and other foods subjected to heavy industrial processing. These products often contain ingredients such as artificial colors, preservatives and emulsifiers.

"The main takeaway for consumers is that it is very easy to get food items into the food supply without really understanding what kinds of effects they have on health, including the health of the brain," lead author Owen Carmichael, Ph.D., of the Pennington Biomedical Research Center in Baton Rouge, Louisiana, told Fox News Digital.

Carmichael said some ultra-processed foods are so heavily engineered that they "look like pharmaceuticals." He contrasted the scrutiny applied to medications with the oversight of foods entering the marketplace.

"Yet they don't face anywhere near the scrutiny pharmaceuticals face when trying to get on the market," Carmichael said. "When it comes to food safety, we sort of shoot first and ask questions later."

Researchers are investigating two leading explanations for the connection between ultra-processed foods and brain health, according to Carmichael. One theory is that these foods can harm the heart and blood vessels, which may indirectly affect the brain.

Carmichael said ultra-processed foods are generally "especially bad for your health from the neck down, damaging the heart, blood vessels, muscle, fat [and] liver." The other theory is that certain additives found in foods may disrupt brain chemistry.

Both possibilities require additional investigation, Carmichael said. Much of the available research comes from animal studies, while long term randomized clinical trials remain lacking.

The authors stressed that the evidence involving processed meat and dementia is observational. It therefore cannot establish that consuming processed meat directly causes dementia.

The review also cited research suggesting that replacing 10% of calories from ultra-processed foods with unprocessed foods could lower dementia risk by 19%. Experts noted that ultra-processed foods account for about 55% of the daily calories consumed by Americans.

Many recommendations for supporting brain health overlap with established advice for the heart, including eating more fruits, vegetables and fish. Carmichael advised people seeking to improve brain health over time to follow the principle of a healthy heart supporting a healthy mind.

Ultra-processed foods tend to be inexpensive, convenient and heavily marketed, making them easy to consume regularly, according to Dr. William Scott Burgin. Burgin is a vascular neurologist at the University of South Florida and chief medical officer for NeuroEM Therapeutics, and he was not involved in the review.

"UPFs are probably the worst for brain health, " Burgin told Fox News Digital. At the same time, he cautioned against treating every food classified as ultra-processed as equally harmful.

"There are foods that get technically classified as ultra-processed, but are more likely neutral or may even be good for you, such as fortified whole grain cereals, dairy-based foods like yogurt, and packaged breads and grain products."

Burgin also pointed out that most evidence comes from observational studies rather than research that assigns participants to specific diets. That distinction limits the conclusions researchers can draw about whether the foods themselves cause dementia.

"All that being said, while I encourage people to reduce their consumption of UPFs, a cookie every now and then is not a problem," Burgin said. He also encouraged eating foods rich in omega-3s, antioxidants and polyphenols, while noting that some evidence supports supplements such as B vitamins.