The MIND diet has gained traction as a research-backed eating pattern designed to protect brain health and lower dementia risk, but the foods you skip matter just as much as the ones you load onto your plate. Researchers behind the diet have consistently pointed to a handful of everyday items that may accelerate cognitive decline, largely because of their saturated fat and sugar content.
“People who eat this diet consistently over the years get the best protection,” said nutritional epidemiologist Martha Clare Morris, PhD, lead author of the MIND diet study with RUSH, per CBS News. “You’ll be healthier if you’ve been doing the right thing for a long time.”
Here’s a closer look at the foods researchers say to limit, and what the latest science says about why.
Red meat and processed meats
Red meat sits at the top of the list of foods to avoid on the MIND diet, and processed varieties like bacon, hot dogs, sausages, salami and bologna carry the strongest warnings. A 2025 study published in Neurology followed 133,771 people with an average age of 49 for up to 43 years and found that participants who ate 0.25 or more servings of processed red meat per day had a 13% higher risk of developing dementia compared to those who ate fewer than 0.10 servings per day.
“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 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.”
The same research found that swapping one daily serving of processed red meat for nuts and legumes was linked to a 19% lower risk of dementia, while replacing it with fish was tied to a 28% lower risk and chicken to a 16% lower risk.
Fast food and fried food
Ultra-processed and fried foods are another category the MIND diet steers people away from. A 2022 study published in JAMA examined dietary data from 10,775 people in Brazil and concluded that “higher consumption of ultra-processed foods was associated with a higher rate of global and executive function decline after a median follow-up of eight years.”
More recent research has drilled down into why. A 2025 study from UNC School of Medicine researchers, published in Neuron, found that a specific group of brain cells in the hippocampus called CCK interneurons become overly active after a high-fat diet, the kind resembling Western-style junk food like cheeseburgers and fries. That overactivity disrupts memory processing, even after just a few days.
“We knew that diet and metabolism could affect brain health, but we didn’t expect to find such a specific and vulnerable group of brain cells, CCK interneurons in the hippocampus, that were directly disrupted by short-term high-fat diet exposure,” said Dr. Juan Song, a member of the UNC Neuroscience Center. “What surprised us most was how quickly these cells changed their activity in response to reduced glucose availability, and how this shift alone was enough to impair memory.”
Butter and margarine
Butter and margarine are foods the MIND diet asks followers to swap out, ideally for olive oil. Findings presented at Nutrition 2023, the annual meeting of the American Society of Nutrition, showed that people who consumed more than half a tablespoon of olive oil per day had a 28% lower risk of dying from dementia compared to peers who never or rarely consumed olive oil. Replacing just one teaspoon of margarine or mayonnaise with olive oil daily was linked to an 8% to 14% lower risk of dying from dementia.
“Our study reinforces dietary guidelines recommending vegetable oils such as olive oil and suggests that these recommendations not only support heart health but potentially brain health as well,” said study author Anne-Julie Tessier, a postdoctoral fellow at the Harvard T.H. Chan School of Public Health. “Opting for olive oil, a natural product, instead of fats such as margarine and commercial mayonnaise is a safe choice and may reduce the risk of fatal dementia.”
Cheese
Cheese is one of the more debated foods on the MIND diet’s avoid list. Many cheeses contain substantial saturated fat, which has been associated with higher levels of LDL (“bad”) cholesterol, and because vascular health and brain health are closely connected, the MIND diet emphasizes foods lower in saturated fat. Several outlets recommend limiting cheese to once a week when following the plan.
But newer research complicates that guidance. A 25-year prospective cohort study published in Neurology found that higher consumption of regular-fat cheese was associated with a modestly lower risk of developing dementia, including vascular dementia, while low-fat cheese showed no significant association. Researchers pointed to cheese’s unique “food matrix,” including fermentation, proteins, minerals and bioactive compounds, as a possible reason it may behave differently than saturated fat alone.
“For decades, the debate over high-fat versus low-fat diets has shaped health advice, sometimes even categorizing cheese as an unhealthy food to limit,” said study author Emily Sonestedt of Lund University in Sweden. “Our study found that some high-fat dairy products may actually lower the risk of dementia, challenging some long-held assumptions about fat and brain health.”
Because the study was observational, it cannot prove that eating cheese prevents dementia. Still, Sonestedt noted, “these findings suggest that when it comes to brain health, not all dairy is equal.”
Sweets and pastries
The MIND diet recommends eating sweets and pastries fewer than five times a week, and a growing body of research suggests why that cap matters. A 2024 study that included 789 participants of the Rush Memory and Aging Project, a community-based longitudinal cohort of older adults free of known dementia at enrollment, tracked participants over an average of 7.3 years.
Of that group, 118 developed dementia. Those in the highest quintile of total sugar intake were twice as likely to develop dementia as those in the lowest quintile after adjusting for age, sex, education, APOE ε4 allele status, non-sugar calories, physical activity and diet score. Exploratory analyses found that the highest versus lowest quintile of fructose intake was linked to a 2.8-times higher dementia risk, and sucrose to a 1.93-times higher risk.
Researchers concluded that “a higher intake of total sugar or total calories from sugar is associated with increased dementia risk in older adults.” Fructose, found in sweetened beverages, snacks and packaged desserts and sucrose, the table sugar used in juices, desserts, candies and commercial cereals, were the simple sugars most strongly tied to elevated risk.
