An anti-inflammatory diet may lower dementia risk, even in people with early signs of Alzheimer’s

Opting for healthy foods such as fruits and nuts instead of ultra-processed snacks adds up over time, research shows. (EMS Forster Productions/Digital Vision/Getty Images via CNN Newsource)

We’ve long known that healthy eating is linked to better brain health.

Now there’s even more evidence, just published in the journal JAMA Network Open, that an anti-inflammatory diet may play an important role in reducing dementia risk — even among people already at higher biological risk for the condition.

What did this study find? What exactly is an anti-inflammatory diet? And what practical steps can people take to keep their brains healthy as they age?

To help with these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and clinical associate professor at George Washington University. She previously was Baltimore’s health commissioner.

CNN: What did this new study find about anti-inflammatory diets and dementia risk?

Dr. Leana Wen: The study followed more than 1,800 adults age 60 and older in Sweden who did not have dementia when the study began. Researchers assessed participants’ diets using detailed food questionnaires over six years and measured three blood biomarkers that are associated with Alzheimer’s disease and other forms of brain injury. They then followed participants for up to 15 years to see who developed dementia. During that time, 240 participants were diagnosed with dementia.

The researchers found that people whose diets had lower inflammatory potential were less likely to develop dementia, including in individuals whose blood tests indicated they were at higher biological risk. Among participants with higher levels of an Alzheimer’s disease-related biomarker called p-tau217, greater adherence to an anti-inflammatory diet was associated with a 29% lower risk of dementia. Similar reductions were seen among participants with higher levels of two other biomarkers linked to nerve cell injury and inflammation.

CNN: What is an anti-inflammatory diet? Is it different from the Mediterranean diet?

Wen: There is no single eating plan officially called the anti-inflammatory diet. Rather, it’s a way of describing an overall pattern of eating that is associated with lower levels of chronic inflammation in the body.

In this study, researchers did not ask participants to follow a specific diet. Instead, they calculated each person’s dietary inflammatory index based on detailed food questionnaires. People whose diets included more vegetables, fruits, nuts, legumes and whole grains and fewer sugar-sweetened beverages, ultraprocessed foods and red meats were gauged to follow diets with lower inflammatory potential.

There is considerable overlap with the Mediterranean diet, which also emphasizes fruits, vegetables, whole grains, legumes, fish, olive oil and other healthy fats. The key takeaway isn’t that there is one ideal diet for everyone. Rather, aiming for a diet with whole, minimally processed foods while limiting ultraprocessed foods appears to be a pattern that benefits many aspects of health, including the brain.

CNN: How might inflammation affect the brain and increase the risk of dementia?

Wen: Inflammation is part of the body’s normal immune response. When you have an infection or an injury, inflammation helps your body heal. The concern is that chronic, low-grade inflammation can persist for years, which researchers believe may contribute to many age-related diseases.

This type of inflammation may damage blood vessels, injure nerve cells and activate immune cells within the brain, all of which may contribute to cognitive decline. At the same time, dementia is a complex condition with many contributing factors, including genetics, presence of vascular disease, hearing loss and lifestyle habits like smoking and heavy alcohol use. Inflammation is probably one piece of a much larger puzzle.

CNN: Should people who have a family history of Alzheimer’s disease or other risk factors change the way they eat?

Wen: I certainly think this study provides another reason to adopt healthy eating habits, but I would be careful not to overinterpret the findings. This was an observational study, which means it cannot prove that diet prevented dementia. Researchers observed what people were eating and what happened to them over time, but they did not randomly assign participants to different diets.

There are other limitations, too. Participants reported what they ate using food questionnaires, which rely on memory and may not always be accurate. The study was also conducted in older adults in Sweden, so the findings may not apply equally to other populations with different diets, lifestyles or genetic backgrounds. In addition, it’s important to remember that having risk factors does not mean someone is destined to develop dementia.

Even so, this is a high-quality study that followed participants for many years. It has an encouraging message, which is that we should be aware of risk factors we can modify. We cannot change our age or our genes, but we can make choices that are associated with better health.

CNN: Besides diet, what other lifestyle habits help reduce dementia risk?

Wen: Regular physical activity is among the most important lifestyle habits. So is controlling blood pressure, cholesterol and diabetes since healthy blood vessels are essential for a healthy brain. Avoiding smoking, limiting excessive alcohol use and getting adequate sleep have also all been associated with better cognitive health.

Staying socially connected and remaining mentally engaged are important, too. Spending time with family and friends, participating in community activities, working, volunteering, pursuing hobbies and continuing to learn new skills all help keep the brain active.

CNN: How else is an anti-inflammatory diet good for you?

Wen: The same dietary patterns associated with lower inflammation have also been linked to lower risks of heart disease, stroke, Type 2 diabetes and some cancers. They also aid with maintaining a healthy weight and improving metabolic health.

Even if future research finds that the effect on dementia is smaller than suggested in this study, eating this way is still likely to provide many other health benefits. People should think about these dietary changes as long-term lifestyle habits rather than a short-term intervention aimed at preventing one specific disease.

What this means, too, is that instead looking for a single “superfood” or choosing a strict diet, focus on your overall eating pattern. Small, sustainable changes — such as eating more vegetables and whole grains, choosing nuts or fruit instead of ultraprocessed snacks, and replacing sugary drinks with water — add up over time. That’s an approach supported not only by this study but by decades of nutrition research across many different health conditions.

Katia Hetter, CNN