Breathlessness

The many causes behind breathlessness

Breathlessness has many possible causes, and gut bacteria are rarely the first thing anyone thinks of. Feeling short of breath can come from lung conditions, heart problems, anaemia, anxiety, or simply being unfit. Anyone with new, unexplained, or worsening breathlessness should see a doctor, since some causes need urgent attention. In two of the less obvious causes behind breathlessness, chronic heart failure and lingering illness after a viral infection, researchers have found a clear, measurable disruption in gut bacteria.

Two lesser-known gut links: heart failure and long COVID

In people with chronic heart failure, a major cause of breathlessness, a study of 53 patients compared with 41 healthy people found clear differences in gut bacteria. Patients with heart failure had lower levels of Faecalibacterium prausnitzii, a key butyrate producer, and higher levels of Ruminococcus gnavus. The same study found an imbalance in gut-produced metabolites, including reduced butyrate and raised levels of trimethylamine N-oxide, a compound linked to hardened arteries.

Gut bacteria can also stay disrupted for months after a viral infection, and breathlessness is one of the symptoms that keeps showing up. A prospective study followed 106 people with COVID-19 for 6 months. Persistent respiratory symptoms, including breathlessness, were linked to an overgrowth of specific gut bacteria, including several Streptococcus species. People whose symptoms had resolved had gut bacteria that looked similar to people who had never been infected, while those with lingering symptoms did not. Gut bacteria measured when patients were first admitted to hospital could help predict who would still have symptoms six months later, before those symptoms had even appeared.

Source: PMC, Metagenomic and metabolomic analyses unveil dysbiosis of gut microbiota in chronic heart failure patients

Source: Gut, Gut microbiota dynamics in a prospective cohort of patients with post-acute COVID-19 syndrome

What this means for you

New or worsening breathlessness always needs a proper medical assessment first, since the cause could be a heart, lung, or blood condition that needs treatment in its own right. Where a doctor has ruled out anything urgent and breathlessness lingers, especially after a heart condition or a past infection, gut-supportive habits may be a reasonable addition to recovery. A wide variety of plant foods each week feeds the same bacteria, including Faecalibacterium prausnitzii, that both of the studies above found depleted in people with ongoing breathlessness. That's the same idea behind GutLab, everyday gut health starts with regularly feeding the microbiome a broad range of plant-rich ingredients.