Summary: Reviewing various studies on Long Covid health outcomes regarding the use of specific gut treatments.
Raphaela I. Lau et. al., (2024) summarised by Rachael McGill
Note that the authors of this study are shareholders in and employees of a private company that develops gut microbiome treatments.
Introduction
An altered pattern of micro-organisms in the gut (the gut microbiome) has been proposed as a contributing factor in Long Covid. Some recent clinical trials have found that altering the gut microbiome using probiotics, prebiotics and faecal matter transplantation (FMT) have led to improvements in Long Covid symptoms, specifically: fatigue; memory loss; difficulty concentrating; stomach upset; disturbances in sleep and mood.
Summary
A reduction in the diversity of the microbes found in the gut is linked to acute COVID-19, potentially through the connection between the gut and the respiratory system known as the gut-lung axis. This study is a review of various investigations published between December 2019 and December 2024 on the alterations in gut bacteria observed in Long Covid and possible treatments to address this. Gut bacteria that showed a positive association with Long Covid in some studies included Bacteroides and Flavonifractor, while those with a negative association included Bifidobacterium and Dorea. An important question is whether the microbial alterations were a cause and/or a consequence of Long Covid. Some animal experiments have supported a direct causal link between the reduced gut microbe diversity associated with Long Covid and the development of some Long Covid symptoms. In terms of treatment, one large trial showed that supplements of three Bifidobacterium species plus prebiotics was effective and safe in alleviating several Long Covid symptoms. Bifidobacterium adolescentis was related with improvement in fatigue, stomach upset and memory loss; Bifidobacterium bifidum with improvement in fatigue and general unwellness; and Bifidobacterium longum with improvement in concentration. Another trial reported a positive effect in patients with post-COVID fatigue treated with probiotics consisting of three Bacillus species.
Other studies had promising results but involved very small numbers of patients. Not all microbiome-based interventions had positive effects on Long Covid symptoms. One trial assessed the effects of supplementation with Bifidobacterium and Lactobacillus, prebiotics, quercetin and calcium butyrate. The decrease in microbial diversity that occurs during the acute phase of COVID-19 was prevented, but no significant difference in symptoms was observed. In another trial, probiotics containing Bifidobacterium and Lactobacillus did not lead to significant improvement in post-COVID symptoms. An alternative way to alter the gut microbiome is faecal microbiota transplantation (FMT), transferring a stool sample from a healthy person to a patient. One study demonstrated that FMT is effective and safe in alleviating insomnia and anxiety, improving sleep quality and reducing daytime sleepiness in Long Covid patients.
Conclusion
Future large-scale clinical trials of microbiome-based treatments could focus on the Long Covid symptoms that were alleviated in previous studies, including fatigue, gastrointestinal upset, difficulty in concentration, memory loss, insomnia and anxiety. The treatments could potentially be extended to other chronic conditions such as chronic fatigue syndrome, chronic insomnia and generalised anxiety disorder.
Read the full paper here
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A large US study of almost 2,000 children and adolescents found that those meeting the research threshold for probable Long COVID were more likely to experience difficulties with grades, attention and participation with friends.
