Food, from the moment it’s in the mouth until it’s excreted as poop, goes through digestion—and this process is a wild journey. Food containing carbohydrates, proteins, or lipids is chewed into a mush in the mouth, where some degree of starch and lipid digestion occurs before it is swallowed. In the stomach, the swallowed ‘ball’ of chewed food is continuously ground and churned until the food particles are small enough to enter the small intestine. Simultaneously, hydrochloric acid (HCl) and pepsin (an enzyme) in the stomach break down complex proteins in the food.
Advancing research reveals that hydrogen can influence gut motility and, in experimental models, shorten transit time. Methane, by contrast, has been shown to slow gut motility and increase transit time. However, findings on the effect of hydrogen sulphide on gut motility and transit time have been mixed. Microbiota research has also pointed to links between imbalances in gut microbiota and intestinal gas levels and gastrointestinal(GI) diseases/symptoms. The study also suggested dysregulated hydrogen sulphide production was associated with greater diarrhoea, urgency, bloating, and symptom severity. However, new techniques are being devised for non-invasive, real-time continuous monitoring of intestinal gases. To capture eliminated intestinal gases (exhaled gas and flatus), researchers have designed respiration/fermentation chambers (airtight rooms with gas sensors and continuous air supply) to explore microbial fermentation activity, track intestinal gases, and monitor the effects of therapeutic interventions. Alternatively, as flatus has relatively higher concentrations of intestinal gases, researchers at the University of Maryland have developed a device that can be attached to underwear. The device, designed to objectively measure hydrogen in flatus, monitors real-time gas profiles and gas-release patterns, providing insights into gut microbial activity and digestive health. Measuring and monitoring real-time gas profiles could enable researchers to expand gut microbiota research: define ‘normal’ and ‘abnormal’ levels in intestinal gases, establish mechanisms behind gas effects, and study diverse populations, involving both healthy people and people with GI diseases, over long periods. Doctors could also potentially tailor a treatment plan—diet or gas-targeted medication—to rebalance the gut microbial ecosystem and modulate gas production and track GI health progress.
A real-world study measured hydrogen, methane, and hydrogen sulphide levels using breath testing in 3,004 participants with GI symptoms, especially excessive bloating and flatulence, from the United States. The study found associations between intestinal gas levels and GI symptoms: higher hydrogen levels (≥20 ppm above baseline) with diarrhoea; higher methane levels (≥10 ppm) with constipation; and higher hydrogen sulphide levels (≥2 ppm) with severe diarrhoea and abdominal pain.
