Many people with ME/CFS experience abdominal pain, nausea, bloating, and alternating constipation and diarrhoea. These gut symptoms are also seen in conditions known as ‘disorders of gut brain interactions’ (or DGBI) such as irritable bowel syndrome (IBS), and recurring symptoms of an upset stomach and indigestion (functional dyspepsia).
DGBI can affect different parts of the digestive system, and like ME/CFS, are more common in women than men.
Key mechanisms of DGBI are thought to include:
- Slower movement of food from the stomach to intestines (gastric dysmotility, delayed gastric emptying or “gastroparesis”);
- Impaired ability of the stomach to relax to accommodate a meal (impaired gastric accommodation);
- Low levels of inflammation;
- An imbalance of the healthy microbes (such as bacteria and viruses) in the gut.
While the potential mechanisms of DGBI have been identified, gut symptoms in ME/CFS remain under-researched. In particular, there is a lack of research in people with ME/CFS considering the body’s response to consumption of food, and the exact digestive symptoms experienced.
A recent study identified this gap in the evidence, and aimed to characterise gut symptoms, gastric dysmotility and gastric accommodation in people with ME/CFS. The researchers then considered whether there were similarities with DGBI – specifically IBS and functional dyspepsia.
What did the study do?
The study included 20 people with ME/CFS (diagnosed according to the Canadian consensus criteria) and 30 similarly aged healthy control participants.
The researchers used ultrasound scans to consider the response of the digestive system to a standard meal (in this case, meat soup) in these participants. They also asked participants to rate the severity of their symptoms including nausea, fullness and upper abdominal discomfort.
Information was collected before consumption of the meal, and again at 1, 10 and 20 minutes after.
What did the study find?
Compared with healthy controls, those with ME/CFS had significantly higher levels of upper abdominal pain, nausea and discomfort before consuming the meal, and at 1, 10 and 20 minutes after. In addition, at 10 and 20 minutes after meal consumption, those with ME/CFS reported significantly higher levels of fullness. The researchers suggest that when considered together, these symptoms indicate that people with ME/CFS had an increase in the pain experienced in internal organs, known as visceral hypersensitivity.
The results from the ultrasound scans also suggested that there were differences in the response of the digestive system to the meal; those with ME/CFS showed impaired gastric accommodation – a finding that the researchers suggest is novel.
This study found that in this small sample of participants, there did seem to be similarities between ME/CFS and DGBI – in particular, functional dyspepsia. These findings may indicate an overlap in the mechanisms between gut symptoms in ME/CFS and those seen in DGBI, particularly the movement of food through the digestive system, and the response of the body to this.
However, more research is needed, in larger sample sizes, to replicate and explore these findings further. In addition, this study did not explore other potential mechanisms of DGBI, including how low levels of inflammation, and an imbalance of the healthy microbes in the gut might explain gastrointestinal symptoms experienced by those with ME/CFS.
Both inflammation and microbes in the gut (known as the gut microbiome) remain important and ongoing areas of research in ME/CFS. For example, existing research has found that there may be differences in the gut microbiomes of people with ME/CFS compared with healthy controls, and newly published research builds on this by identifying two specific types of bacteria in the gut of people with ME/CFS which, with much more research and testing, have the potential to act as biomarkers for ME/CFS.