Breath Hydrogen (H₂) and Methane (CH₄) Excretion Patterns in Normal Man and in Clinical Practice

Breath H 2 and CH 4 daily excretion patterns were studied in 20 healthy individuals whilst on their regular diets and fasting. The average H 2 excretion level was found to be 85 ml day ‐1 on habitual meals and less than 35 ml day ‐1 whilst fasting. The mean excretion in breath at any one time was less than 0·5 µmol.l –1 and individual breath sample excretion rarely exceeded 0·90 µmol.l –1 . H 2 excretion followed a regular pattern, being high in the morning, falling until about mid‐day and rising during the early afternoon. The pattern of excretion remained essentially similar from day to day. Fasting decreased the overall excretion level and abolished the afternoon rise. CH 4 excretion did not follow any regular pattern over the day and was individual with a third of the participants excreting above 0·1 , µmol.l –1 and the rest nothing or below 0·10 µmol.l –1 . In 15 of the subjects mouth‐to‐caecum transit time was measured employing the breath H 2 test and using three different oligosaccharides of different molecular weight and varying osmolalities. The mouth‐to‐caecum transit time (MCTT) for lactulose was found to be 90±7 min, for raffnose 168±35 min, and for stachyose 290±0 min. Fasting and different osmolalities of the same oligosaccharides did not alter the MCTT. Administering the three oligosaccharides to a patient with colostomy did not show a difference in the H 2 evolution time. Using the breath H 2 test as a method of detection of lactose intolerance showed that the test is relatively more reliable, non‐invasive and simple when compared to blood glucose measurement of mucosal lactase activity.