Gut microbes play a significant role in the central nervous system — digestive health is linked to your risk of neurodegenerative diseases

Right now, we are seeing neurodegenerative diseases like Parkinson’s and Alzheimer’s in unprecedented numbers – and these figures are only expected to rise in the future. In fact, the number of Alzheimer’s patients in the United States is expected to grow from 5 million today to 14 million by the year 2050, which is roughly equivalent to the entire populations of Los Angeles, New York City, and Chicago combined.

It’s clear that this is one of the biggest health challenges of our time, and scientists have recently gained new insight into the connection between the brain and gut health. Researchers from Brigham and Women’s Hospital in Boston used animal models as well as human cells to examine the gut-brain connection and explore the crosstalk between brain cells and immune cells.

In particular, they focused on how gut microbes influence two types of crucial central nervous system cells: astrocytes and microglia. Microglia play an important role in the immune system, getting rid of materials that need to be removed from the central nervous system such as damaged cells and plaques. However, they also create compounds that can be neurotoxic to the astrocyte brain cells. It is this damage that contributes to neurological illnesses like multiple sclerosis.

The researchers found that gut organisms can promote brain inflammation in previous studies, but this is the first study to explain how microbial products can act on microglia to stop inflammation. In short, microbes produce certain byproducts when breaking down the amino acid tryptophan – which is found in foods like turkey – and these byproducts are believed to limit brain inflammation via their influence on microglia.

They reached their conclusions after examining gut microbes and changes in mouse models of multiple sclerosis. They discovered the compounds produced by the breakdown of tryptophan cross the blood-brain barrier and activate an inflammatory pathway that can limit neurodegeneration. They saw evidence of this same pathway when looking at brain samples from humans with multiple sclerosis.

It is the activation of this pathway that has also recently been linked to glioblastoma and Alzheimer’s disease. The researchers say, therefore, that these mechanisms could be relevant to a host of neurological diseases beyond multiple sclerosis and lead to the development of new therapies for these types of illnesses.

The results also indicate that making changes to your diet can make a difference when it comes to your neurological health. The results were published in the Nature journal.

Brain-gut connection is stronger than most people realize

Other studies have shown that emulsifiers in packaged food can cause changes in the gut microbiome that lead to the type of inflammation associated with metabolic syndrome, which itself has been linked to a higher risk of Alzheimer’s disease, along with diabetes, heart disease, and liver disease.

Gut microbes have also been found to modulate levels of serotonin in your brain, giving them a direct impact on your mood as well as brain chemistry. Some studies have suggested that certain microbes release chemicals that change the activity in the vagus nerve, which runs between the gut and the brain. Researchers say that microbes can manipulate behavior, produce toxins that make people feel bad, change their taste receptors, and release chemical rewards that make them feel good.

If you want to ensure your intestinal flora stays balanced, it is a good idea to consume probiotics and prebiotics while avoiding processed foods and refined sugars.

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