Can a healthy diet prevent Alzheimer's?

– June 12, 2023

Exploring the role of our gut microbiota in the development of the neurodegenerative disease Alzheimer's.

The Brain-Gut Connection

Our intestines are filled with microbes. In fact, every person carries around 1.5 kilograms of microbes in their intestines! These microbes help us digest our food. But recently, it has become more apparent that our brains and intestines are directly connected through a nerve pathway called the brain-gut axis. This means that mental health issues are often related to gut problems. Our gut microbes also play a role in this: certain microbes produce toxins that trigger inflammation in our intestinal lining and make our blood-brain barrier more permeable.

Microbes and Alzheimer's

Researchers have even discovered that the composition of your gut microbiome is linked to the development of Alzheimer's! It turns out that Alzheimer's patients have a much less diverse gut microbiome compared to healthy individuals. Additionally, a correlation has been found between a protein known as a risk factor for Alzheimer's, Apolipoprotein E ε4, and the composition of the gut microbiome. A new study has now investigated which microbes in our intestines have an impact on the development of Alzheimer's.

The researchers from the Nevada Institute of Personalized Medicine (NIPM) examined 119 bacterial genera. Among them, six were found to protect against Alzheimer's development: Eubacterium nodatum group, Eisenbergiella, Eubacterium fissicatena group, Adlercreutzia, Gordonibacter, and Prevotella. On the other hand, the four genera Lachnospira, Veillonella, Collinsella, and Bacteroides were found to pose a risk.

How does it work?

One of the risk factor genera is Collinsella. This group of bacteria has previously been associated with the development of rheumatism, arthritis, and type 2 diabetes. The amount of Collinsella is increased in the gut microbiome of Alzheimer's patients. Collinsella triggers inflammation and makes our intestinal wall more permeable. There is also a correlation between Collinsella levels and cholesterol levels in the blood. Veillonella is also elevated in both the gut and mouth of Alzheimer's patients, creating inflammation by activating the immune system. Therefore, it is important to learn more about the interactions between our bodies and these groups of bacteria, so that we can prevent these diseases in the future.

The genera that have a protective function likely do so by producing short-chain fatty acid butyrate or the substance Urolithin A (UA), both of which have anti-inflammatory effects. Butyrate also reduces the permeability of the intestinal wall. UA ensures that deceased mitochondria are destroyed, a process that is insufficient during the progression of Alzheimer's.

Diet for a healthy microbiome

Our diet has a significant influence on the composition of our microbiome. For example, the protective genus Prevotella is more abundant in people who follow a vegan or Mediterranean diet, while the risk factor genus Bacteroides is more prevalent in the microbiome of people with a diet rich in fats and proteins.

Living with your microbes

All in all, it is becoming increasingly clear: if we take good care of our microbiome, our microbiome will take good care of us. By studying the ways in which our bodies interact with the hundreds of species of bacteria living in our intestines, we can determine which diets support the growth of beneficial bacteria. This may eventually lead to the prevention of Alzheimer's in the future.