Study: The Mediterranean Diet Protects Brain Health, Fights Against Alzheimer’s

While the majority of the 6 million people living with Alzheimer’s in the US get diagnosed at age 65 or older, there are about 200,000 younger Americans who have been diagnosed with early-onset Alzheimer's. Now researchers believe that brain aging, neurological disorders and diseases such as dementia and Alzheimer's can be delayed and even deterred through lifestyle choices, especially diet. A new study just revealed that eating a Mediterranean diet, rich in vegetables and fruits, whole grains and nuts, seeds, and some fish–and with little or no saturated fat in red meat and full-fat dairy–protects against brain aging, Alzheimer's, and dementia.

This would be good news for anyone who has watched a loved one deteriorate from brain diseases such as Alzheimer's. The unfortunate state of this disease is that there isn’t any cure, and drug treatments cannot stop the progression, leaving those with a family history dreading the notion that they may be edging closer, every time they forget a name, or can't pull the right word out of their brains. The Alzheimer’s Association states that, on average, a person diagnosed with Alzheimer’s may live four to eight years after being diagnosed depending on various factors, but some live much longer.

Alzheimer’s disease is a neurodegenerative condition that impacts brain function when plaques, or clusters of protein fragments, build up between nerve cells, while tangles, made of another type of protein, crop up like unruly vines wrapping around brain cells and diminishing their ability to send and receive signals that are essentially the way your brain processes and communicates.

These unwelcome developments hinder the connection between the brain cells, so your brain can't make the same connections and retrieve facts, names, or scenes from memory the way it once could. Symptoms usually start out mild, but as the disease progresses it interferes with daily life by making memory cloudy, and as the brain loses its ability to act as the body's central command and control, dementia and Alzheimer's eventually robs individuals of the inability to hold a coherent conversation, complete daily tasks, function independently, or respond to their environment.

Now a new promising study tells us that following the Mediterranean diet—rich in vegetables, fish, fruits, and legumes and low in red meat and saturated fat–has been found to be protective for brain health, and may even work to reduce the risk of neurodegenerative diseases such as Alzheimer's and dementia. While the causes of these disorders are not fully known, lifestyle choices appear to play a role in the disease and its progression over time.

Here’s what new research has to say about the link between Alzheimer’s disease and how the Mediterranean diet can reduce your risk or delay any potential onset of brain disease.

Our brain is a complex organ that contains billions of neurons that move information via electrical and chemical signals. These messages get sent to other parts of our brain via synapses, but also through our nervous system to our muscles and organs. Our neurons contain 3 essential parts — the cell body, dendrites, and the axon. The cell body holds the nucleus, which keeps the cell activity in check. The dendrites branch out from the cell body and wait to collect information from other neurons. The axon is like the stem of the neuron and releases messages to other neurons.

According to the National Institute on Aging, in order to function normally, neurons require communication from other neurons, fuel from oxygen and glucose, and the ability to repair, remodel, and regenerate. With Alzheimer’s disease, these processes become disrupted and result in neurons dying.

The cause of these neuron deaths is due to protein deposits called beta-amyloid proteins and tau proteins. Beta-amyloid proteins clump together and form plaques that sit between neurons and disrupt the communication between them. Tau proteins are found inside the neurons, which is normal when they are healthy, but Alzheimer’s disease creates a chemical change that causes tau to start sticking together, forming threads called tangles inside and outside the cell, which blocks their ability to communicate or connect with other cells.

Doctors are still investigating exactly what it is that causes these plaques and tangles, and the question remains how much is genetic and how much is driven by lifestyle choices like alcohol, sleep, stress, and diet.

Scientists at the DZNE (German Center for Neurodegenerative Diseases) found that eating a Mediterranean diet of mostly plant-based food (and avoiding meat) on a regular basis could be protective against protein deposits occurring in the brain and also minimize brain shrinkage that occurs as we age.

The study, published in Neurology, oversaw 512 subjects around the age of 70. Of those, about one-third, or 169, were cognitively healthy, while the other two-thirds, or 343, were at high risk of developing Alzheimer’s disease. In order to determine what the participants were eating, researchers had each person self-report their dietary habits (via a questionnaire) to indicate which foods (out of 148) they ate in the past several months. Participants scored higher if they frequently ate foods that are common on the Mediterranean diet. This includes fish, fruits and vegetables, legumes, grains, and monounsaturated fats, such as olive oil.

Then the researchers conducted brain scans using magnetic resonance imaging (MRI) scanners to investigate brain shrinkage and put the study participants through mental acuity and neuropsychological tests to determine cognitive abilities. Meanwhile, 226 subjects were also measured for amyloid-beta proteins and tau proteins in their cerebrospinal fluid.
The results found that unhealthy diets higher in saturated fat and lower in plant-based foods such as fruits and vegetables had higher biomarker levels of amyloid-beta proteins and tau proteins, compared to the individuals who ate foods on the Mediterranean diet. The memory tests also indicated that those who were not following the Mediterranean diet performed worse than those that ate a mostly plant-based diet.

“There was also a significant positive correlation between a closer adherence to a Mediterranean-like diet and a higher volume of the hippocampus. The hippocampus is an area of the brain that is considered the control center of memory. It shrinks early and severely in Alzheimer’s disease,” Tommaso Ballarini, Ph.D., lead author of the study, explained in an interview.

The goal for the researchers of this study is to continue to follow these participants and examine them over the next five years. This will give the researchers the opportunity to see how the participants' nutrition has continued, regardless if they remained on the Mediterranean diet or not, and how diet impacts their brain and neurological aging over time.

“It is possible that the Mediterranean diet protects the brain from protein deposits and brain atrophy that can cause memory loss and dementia. Our study hints at this,” states Ballarini. “But the biological mechanisms underlying this will have to be clarified in future studies.”

Other similar studies have come to the same conclusion. Another study published in Neurology from 2018 followed 70 participants with normal cognition. 34 of the participants had high adherence to a Mediterranean-style diet, whereas the other 36 didn’t. When clinical and neuropsychological measures were taken, the results found that those who had higher adherence to the Mediterranean diet had about 1.5 to 3.5 years of protection against Alzheimer’s disease.

Bottom Line:  Eating a Mediterranean diet appears to fight against brain aging, dementia, and Alzheimer’s disease. And while these diseases are incurable, lifestyle choices such as a plant-based diet appear to offer some protection against early onset. Follow a diet high in fruits, vegetables, legumes, and healthy fats may help to prevent normal brain aging and the onset of Alzheimer’s disease.