A new study links the length and severity of a person's experience of COVID-19 with the state of their gut microbiome
There are also potential implications for who goes on to experience so-called 'long COVID'
Experts have warned, however, that the study is 'observational' – as such, a link between your gut microbiome and how you experience COVID has not been proven, with deeper research required
The work, published in the journal Gut, comes from a team at The Chinese University of Hong Kong
Another day, another piece of science to suggest that your gut may play an even more substantial role in your overall health than ever before.
New research, published in the journal Gut, indicates that there could be a link between your gut microbiome – the collection of microorganisms that live in your digestive tract – and how severe your experience of COVID-19 is. The study's authors say that patients they analysed with COVID-19 had depleted levels of several types of gut bacteria, which are understood to be associated with your immune response.
An imbalance of bacteria in your gut microbiome could also have something to do with on-going symptoms that persist after the typical timeframe for recovery – which most of us know as 'long COVID.'
Scientists conducted this work by analysing blood and stool samples, as well as medical records, from 100 patients (which, no, isn't very many) in hospital with confirmed COVID-19. These were contrasted with data taken from 78 people without the disease.
As a result of the research, Professor Siew Ng, of The Chinese University of Hong Kong, thinks that people with high levels of 'good' gut bacteria have a 'substantially better' chance of experiencing a less debilitating form of the disease, should they develop it.
Experts not involved with the research have cautioned, however, that this is an 'observational' study – meaning that a link between your gut bacteria and your experience of COVID-19 has not been conclusively shown, with more involved research required. Essentially, it is possible that the disease itself, or even a factor such as the stress of hospitalisation, changes a patient's gut microbiome, as opposed to being the root cause of incurring a nasty form of the illness.
What do the experts say?
Of the findings, Prof Daniel M Davis, Professor of Immunology at the University of Manchester, said:
‘Our knowledge of gut microbes has exploded in recent years. Variations have been associated with diseases as diverse as asthma, multiple sclerosis and cancer. So it’s perhaps not so surprising that the severity of COVID-19 also correlates with the composition of a person’s microbiome.
'But the details here are important. A particularly striking finding was that distinct characteristics in a person’s gut microbes persisted after clearance of the virus. It is possible that these changes could contribute to the symptoms of so-called ‘Long-COVID’. At the moment this idea is still speculative but it demands further investigation, especially given the huge importance of understanding ‘Long-COVID.'
He warned, however that: 'Overall, this new research doesn’t yet led to a clear public health message in terms of treatments or therapies, but does set the scene for a hugely important realm of new science.'
Dr Kaitlin Wade, Lecturer in Epidemiology at the University of Bristol, raised concerns around taking the study's findings at face value.
'This is interesting work, but there needs to be an appropriate examination of the quality of evidence before generating strong inference about the role of gut microbiome in COVID-19 causally. It’s important to emphasise this is an observational study, so it cannot indicate whether variation in the gut microbiome is determining COVID-19 severity or whether the virus itself has caused this variation. It’s therefore perfectly possible that changing the gut microbiome may not influence COVID-19 infection prognosis at all.
'The sample size is also very limited and there could be issues with bias in their selection of hospital patients, including age range.
'The key message here should be one of considerable caution. Although some evidence potentially linking COVID-19 and the gut microbiome has been found, much further and deeper research is required to understand this complex relationship and draw meaningful conclusions. Until it can be clearly evidenced that changing the gut microbiome alters COVID-19 risk, it would not be appropriate to suggest measures to improve gut health would increase resilience to COVID-19.'
How do I help out the 'good bacteria' in my gut?
Whether or not the science ultimately affirms a link between your 'good' gut bacteria and avoiding a more intense form of COVID-19, a healthy gut is well worth cultivating – like you know, such a state of affairs has been linked with everything from a happier mood to bolstered immunity. Gut health expert and author of Eat Yourself Healthy, Dr Megan Rossi, advises that you keep yours in check by following these key points:
Eat a diet rich in plants, from vegetables and fruit to legumes and nuts. Hit 30 different plants a week and you'll fuel a healthier gut microbiome
Spend more time outdoors, in nature
Exercise and move your body regularly
Make sure you're getting high-quality sleep
Reduce your stress levels, via habits like meditation and yoga
Eat fermented foods, like sauerkraut and kimchi, as well as drinks like kefir and kombucha
Try not to imbibe more than two standard sized alcoholic drinks a day
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