Alzheimer’s disease: Could Mediterranean, MIND diets help reduce brain plaques?

Past research shows Alzheimer’s disease has a profound effect on two specific types of protein in the brain.

The first is called beta-amyloid. When a person has Alzheimer’s, the naturally occurring beta-amyloid protein changes its conformation and becomes “sticky.” This causes it to form clumps, also known as plaques, in the brain. These plaques gather between neurons, disrupting communication between them.

The second protein negatively affected by Alzheimer’s disease is tau. Tau naturally occurs inside neurons and helps them stay straight. When someone has Alzheimer’s, abnormal amounts of tau protein can collect inside neurons, forming tangles. These tangles block the neuron’s transport system, disrupting communication between them.

The Mediterranean diet focuses on eating the foods people in the Mediterranean region of the world normally eat. This includes:

People following the Mediterranean diet eat very little dairy products and red meat. They also do not eat heavily processed foods, hydrogenated oils, sugary beverages, or desserts.

The MIND diet is a combination of the Mediterranean diet and the DASH diet, which aims to reduce high blood pressure. The purpose of the MIND diet is to promote brain health.

People following the MIND diet focus on eating:

• vegetables, especially green leafy ones
• berries
• nuts
• olive oil
• fish and poultry
• legumes
• whole grains
• red or white wine, no more than one glass per day

People on the MIND diet are told to avoid butter and margarine, cheese, red meat, sugary processed desserts, and fried foods.

According to Dr. Puja Agarwal, assistant professor in the Department of Internal Medicine, a nutritional epidemiologist at Rush Alzheimer’s Disease Center, RUSH University, and lead author of this study, she and her team decided to study the potential effects of the MIND and Mediterranean diets on people with Alzheimer’s disease because Alzheimer’s is the most common neurodegenerative disorder affecting our fast-growing aging population.

“With limited treatments to reverse memory loss or dementia, understanding the role of modifiable risk factors such as diet may have a public health impact,” she told Medical News Today. In this observational study, we followed older adults from the time they (enrolled) in the study until their death. We obtained information on what they (ate) during follow-up and then assessed Alzheimer’s disease pathology — amyloid and tangles — in the brain among those who donate their brains at the time of death to find how what they ate is related to plaques and tangles in the brain.”

Dr. Agarwal stated the study included people with and without Alzheimer’s disease. Proximate to death, 39% of participants had been diagnosed with dementia. And when examined after death, 66% met the criteria for Alzheimer’s disease.

Upon analysis, the research team found an association between following the MIND or Mediterranean diets with fewer Alzheimer’s disease plaques and tangles.

“These results are not surprising but encouraging because improvement in people’s diets in just one area — such as eating more than six servings of green leafy vegetables per week, or not eating fried foods — was associated with fewer amyloid plaques in the brain similar to being about four years younger,” Dr. Agarwal said.

“These results are exciting, indicating that healthy diets such as MIND or Mediterranean diets may lower the risk of Alzheimer’s disease,” she continued. “Considering these results, doctors may recommend these healthy diets to older adults at risk of Alzheimer’s disease.”

As for the next steps in this research, Dr. Agarwal said they plan to further investigate other potential mechanisms through which diet may have a protective effect on the brain, via examining its relationship with cerebral vascular and other pathologies, detailed neuroimaging, and newly established plasma neurodegenerative and metabolic biomarkers.

“We also plan to investigate various person-specific factors and capitalize on emerging in-vivo biomarkers and human brain tissue when available, especially in a diverse sample including more participants from different races/ethnicities,” she added.

Medical News Today also spoke with Molly Rapozo, RDN, registered dietician nutritionist and senior nutrition and health educator at Pacific Neuroscience Institute in Santa Monica, CA, about this study. Rapozo was not involved with the study.

“I’m an advocate for both diets, however, I do prefer MIND as a newer hybrid of Mediterranean and DASH, with modifications based on the science of nutrition and the brain,” she explained. “I appreciate the emphasis on foods that contain nutrients important for the brain. For instance, the MIND Diet is prescriptive of leafy greens which stood out as being protective in this recent study. Discussing the specific foods to include in the MIND Diet helps consumers learn about nutrient density — for example, the antioxidant value of berries.”

For those looking to make quick changes to their diet to improve brain health, Rapozo recommended incorporating more whole plant foods into your diet.

“If leafy greens aren’t a staple already, this could be a great place to start,” she added.”There are so many ways to include leafy greens.”

Ideas from Rapozo include:

• Start at breakfast with eggs and sauteed greens, or add a handful of spinach to your morning smoothie.
• Have an entrée salad for lunch.
• Enjoy a side salad with dinner.
• Add prewashed and ready-to-eat greens to sandwiches, wraps, tacos, etc.
• Hearty greens like baby kale last longer in the fridge and may be incorporated into mixed dishes like soups, stews, and casseroles.
• Try a new leafy green or incorporate greens in a new way — for instance, bake escarole with salmon on a sheet tray.