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The Many Causes of Fatigue

februari 28, 2022

Fatigue is a clinical symptom that we see a lot at Nordic Clinic, which accompanies most medical conditions. These conditions range acute to chronic, simple to complex, and infectious to behavioural. Indeed, treating chronic fatigue requires assessing a patient from nearly every possible angle to find the cause of fatigue.

Chronic fatigue can also be a product of multiple issues. While infectious disease normally has a single pathogen at play, these pathogens can alter our nutritional status and impact our behaviour to promote fatigue. So, in addition to treating the pathogen, you may also have to address the devastation the pathogen caused.

Infection As a Cause of Fatigue

Most infections, both viral and bacterial, cause fatigue. For most people, this is an acute problem that resolves with eliminating the pathogen. This is simply a normal component of how our immune system works.

Unfortunately, for some, the acute problem becomes chronic. These chronic effects are often attributed to a prolonged course of infection. However, something else may be going on. One paper finds that people with post viral syndrome have neuroinflammation in their brain.1 The initial infection may also cause devastation that needs to be cleaned up, such as nutritional deficiency or behavioural changes.

Chronic GI Disorders As a Cause of Fatigue

Chronic gastrointestinal (GI) disorders also have fatigue as a common symptom.2 Celiac disease, IBS, IBD, and functional dyspepsia all present with fatigue. Interestingly, functional GI disorders also develop after infectious disease, as in post-infectious IBS (when you develop IBS after food poisoning).

With most GI disorders, patients experience nutritional deficiency due to poor digestion and absorption. Additionally, the symptoms of GI disorders alter behaviour and disrupt important things like sleep and stress, which also lead to fatigue.

Behavioural Drivers of Fatigue

Many different things we do lead to fatigue. Burnout is the classic case, where someone burns the candle at both ends. Over time, poor stress management, inadequate sleep, and excessive physical demands are just some lifestyle factors that lead to burnout.

Poor nutrition also causes fatigue. Iron deficiency, even without anaemia, results in fatigue that corrects with increasing iron intake.3 Deficiency in various other nutrients also causes fatigue. It’s important to point out that poor intake or absorption are not the only causes here. Often, there is a nutritional cost to infection that increases dietary needs to enhance recovery.

Finally, disruption to our circadian rhythms leads to fatigue. Circadian rhythms control our physiology, making us alert during the day and ready to fall asleep at night. When disrupted, as in jet lag or shift work, this leads to alterations in hormones and neurotransmitters (chemical messengers in the brain) that cause fatigue. Many behavioural factors, such as activity levels and timing, food timing, and light exposure regulate our circadian rhythms.

Stress Is Not Always The Problem

Yes, most of us are excessively stressed, and yes, excessive stress leads to fatigue. But we have seen many patients where their doctor has put down their symptoms due to stress and stress alone. Many of these patients never get well because they are solely focused on treating their stress. Whilst stress is a contributory factor, if there is untreated infection (or another medical condition), post infectious destruction, nutritional deficiency, gut imbalances, lifestyle factors such as poor sleep, or a combination of two or more of those, they all need to be addressed.

Solving Fatigue Often Requires a Multifactorial Perspective

Addressing chronic fatigue is not as simple as giving somebody a pill and telling them to come back in a month – we wish it was. Often, fatigue is multifactorial and requires a deep patient history and integrative testing to identify the causal drivers. You must really think about what has happened to your body physically, emotionally, and mentally, as well as ruling out medical factors. This will allow you to successfully address, with the help of the right medical, nutritional or health practitioner, the infectious, nutritional, and behavioural causes of fatigue.

If you would like to learn more about fatigue, we will be discussing all things related to fatigue in our upcoming free webinar on this topic. The webinar is a collaboration with Food Pharmacy and we are privileged to have Lina Nertby Aurell hosting the webinar. To read more about the webinar and to sign up, click here

This article was originally published as a guest editor post at foodpharmacy.se

By: Graeme Jones, clinical physiologist and CEO at Nordic Clinic Stockholm. 

Published: 28/02/2022


1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4392663/

2. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2036.2008.03770.x

3. https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/iron-deficiency-without-anaemia-is-a-potential-cause-of-fatigue-metaanalyses-of-randomised-controlled-trials-and-crosssectional-studies/F7E59D4BFC154E9687E42CDCC4968EAF

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