Chronic fatigue: changes in intestinal bacteria could explain your symptoms

Beatriz Carpallo, researcher at the IIS Aragón, speaks in this article in 'The Conversation' about chronic fatigue, the microbiota and persistent covid.

I don't have the strength, I'm always tired, I'm dying of sleep. I sleep a lot but wake up without energy. In addition, I suffer pain in many areas of the body and if I make extra effort, I will pay for it. My memory fails a lot and it is difficult for me to concentrate on things. Everything exhausts me; I'm tired of living like this.

This is the real testimony of a patient with chronic fatigue, a problem suffered by between 2 and 6% of the population in developed countries and about 900 people in Spain. In her case, she appeared after a SARS-CoV-2 infection.

Although the cause is not yet clear, it affects people diagnosed with Fibromyalgia already many patients with post-covid condition, official World Health Organization definition for what is also known as persistent covid.

A real evil with numerous symptoms

For a long time, some healthcare professionals have doubted its existence – and even continue to do so today – due to the lack of biomarkers to diagnose it. This makes treatment much more difficult and patients do not understand what is happening to them either.

However, chronic fatigue syndrome has been known for years. It is detected when it lasts more than six months (even years) and does not improve with rest. Apart from fatigue, it is usually accompanied by symptoms such as brain fog, discomfort after exertion, headaches, muscle or joint pain and a low mood.

The appearance of cognitive and emotional alterations may have influenced the belief that it is an exclusively psychological problem, but this is not the case: at a physiological level, chronic fatigue is related to an increase in proinflammatory substances in the body due to an exaggerated activation of our defensive system.

In recent times, researchers have also linked this disease with an alteration of the intestinal microbiota, the ecosystem of microorganisms that live in our intestine. They feed on what we eat and in exchange they generate useful and necessary substances for us. And as we will see below, its imbalance could explain the cognitive and emotional symptoms that characterize chronic fatigue.

The price of neuroinflammation

When the body has high levels of inflammation, proinflammatory substances have the ability to reach the brain and modify the action of microglia, cells that collaborate with neurons. This can start a cascade of inflammatory changes in the brain.

But this organ does not have pain receptors, it does not hurt. Therefore, inflammation manifests itself differently: with brain fog, decreased thinking speed, tiredness, depression, drowsiness, fatigue, lack of motivation, etc. That is, symptoms very similar to those reported by patients with chronic fatigue syndrome with high levels of inflammation.

Although the mechanisms are still not completely clear, changes in the microbiota could affect the immune system, which would “neuroinflammation” of the brain. So it is very possible that the aforementioned mental symptoms are related to what happens in the intestine, as more and more scientists point out.

Tracking the gut-brain axis

Thus, A study carried out at Cornell University (New York) showed that people with chronic fatigue not only had a reduced and altered microbiota, but also had a greater intestinal permeability. This hypermeability may be related to the patients' inflammation.

For its part, a 2022 investigation found that the proliferation of certain bacteria in the small intestine They can also trigger cognitive alterations.

All this reinforces the idea of ​​the involvement of gut-brain axis and the action of neuroinflammation. In fact, other investigation concluded that the intestinal and lung microbiome play a fundamental role in the development and treatment of the post-covid condition.

A trickle of evidence

It is also true that a systematic review of 2018 could not establish any relationship between the microbiota and chronic fatigue. This is explained because many investigations had not assessed the large number of drugs that those affected take, capable of altering the community of microorganisms that inhabit our intestine.

But that same year, a study published in the journal Frontiers in Microbiology denied it, linking two types of microorganisms – of the genus Paraprevotella y Ruminococcaceae UCG_014– with the risk of looking like chronic fatigue syndrome.

To this we must add another work from 2018 published in the magazine Cell Host & Microbe which found less diversity in the microbiota of those affected; specifically from bacteria that produce a molecule called butyrate.

These changes in the microbiota may be due to the intake of medications, diet, or having suffered a viral infection. certain viruses or bacteria.

What can we do to improve the microbiota?

It is true that each person has their own community of microorganisms and that it must be analyzed individually, but there are certain probiotics - such as those rich in Bifidobacteria infantis of the strain 35624– which appear to reduce inflammation.

Lifestyle also influences. Practicing outdoor activities, reducing stress, respecting sleep-wake cycles or reducing the consumption of antibiotics and antacids helps keep our microbiota healthy.

And as for the eating, it is usually recommended to reduce the consumption of ultra-processed foods, sugars and gluten and increase the consumption of fruits, vegetables and oily fish (rich in omega-3).

It seems that a field of study is opening up with possible solutions, but also with many doubts pending resolution.

Authorship: Beatriz Carpallo Porcar: teacher in the Physiotherapy and Nursing degrees at the San Jorge University. Researcher on Post Covid Condition at the Aragon Health Research Institute, San Jorge University