Wearable hydrogen sensor accurately detects lactose-induced flatulence in double-blind study

A small hydrogen sensor worn near the perineum has revealed that individuals are unreliable at estimating their own daily flatulence frequency. Brantley Hall at the University of Maryland designed the sensor, which is the size of a medium-sized coin such as a nickel or two-pence piece and a couple of coins thick.

Hall and his colleagues recruited 37 people to wear the device while following a low-fibre diet for two days to establish a baseline of farting.

On the morning of the third day, each participant received either 20 grams of lactose or 20 grams of sucrose. On the fourth morning, participants consumed the other sugar. The study was double-blind, with neither participants nor research teams knowing who received lactose or sucrose on which day.

5 times more than their baseline the day after consuming it. For 22 of those 24 lactose-sensitive participants, the day with higher gas production corresponded to lactose consumption. Yet an accompanying survey showed the same participants correctly guessed which day they were gassier only 50 per cent of the time.

“It’s literally like a coin flip. People aren’t reliable narrators about their flatulence patterns,” Brantley Hall said. In healthy adults, daily fart count ranges between 4 and 59, with the average being 32.

Hall said the average figure of 32 is likely to go down over time because studies are probably biased towards people who are farting a lot. Hall and colleagues are trying to establish the baseline of healthy human flatulence patterns, including how many times a day people fart and what foods are the major causes.

Producing excess intestinal gas is a hallmark of lactose intolerance because microbes ferment undigested lactose and produce hydrogen.

About one-third of people with lactose intolerance don’t report symptoms, sometimes because they don’t know they are farting. Hall will present the results at the Digestive Disease Week 2026 conference in Chicago on 4 May. Tom van Gils at University of Gothenburg in Sweden reviewed the approach.

“Measuring flatulence right where the gas leaves the body by using non-invasive smart-underwear is interesting, especially given the good acceptability of the technique,” Tom van Gils said. @NewScientist reported that the device offers an objective way to determine gas production that could help diagnose conditions such as irritable bowel syndrome and assess how well drug treatments reduce intestinal gas.

The same outlet noted that Hall’s earlier work with colleagues produced the healthy-adult fart-count range now being refined.