Evaluation of lactulose, lactose, and fructose breath testing in clinical practice: A focus on methane

Abstract

Background and Aim Breath testing (BT) is used to identify carbohydrate malabsorption and small intestine bacterial overgrowth. Measuring methane alongside hydrogen is advocated to reduce false‐negative studies, but the variability of methane production is unknown. The aim of this study is to examine the effect of high methane production on hydrogen excretion after ingesting lactulose, fructose, or lactose. Methods A retrospective audit was performed of patients with gastrointestinal symptoms who underwent BT. Following a low fermentable carbohydrate diet for 24‐h, a fasting BT before consuming 35 ml lactulose, 35 g fructose, or lactose in 200 ml water, followed by BT every 10–15 min for up to 3‐h, was performed. A positive test was defined as a ≥20 ppm rise of hydrogen or methane from baseline. A high methane producer had an initial reading of ≥5 ppm. Breath hydrogen and methane production were measured as area under the curve. Chi‐squared tests were used to compare proportions of those meeting the cut‐off criteria. Results Of patients, 26% (28/106) were high methane producers at their initial lactulose test. The test–retest repeatability of methane production was high, with the same methane production status before ingesting lactose in all (70/70) and before ingesting fructose in most (71/73). Methane production was highly variable during testing, with 38% (10/26) having ≥1 reading lower than baseline. Hydrogen produced by high or low methane producers did not differ (1528 [960–3645] ppm min vs 2375 [1810–3195] ppm min [P = 0.11]). Symptoms and breath test results were not positively related. Conclusion The validity of including an increase of ≥20 ppm methane to identify carbohydrate malabsorption or small intestine bacterial overgrowth should be questioned due to the variability of readings during testing.

Modification of baseline status to improve breath tests performance

“…Probably, this difference could be due to the different type of population analyzed. Prevalence of elevated CH 4 , baseline levels in our work was similar to that observed in a study of Harvie et al 17 who estimated a prevalence of 26% of high CH 4 producers. However, they established 5 ppm as baseline cut-off.…”

“…To our knowledge, this is one of the first studies with larger sample size focused in baseline breath measurements. First of all, we observed the presence of methanogenic microbiota determined by the presence of CH 4 in breath, in a high percentage of the patients, higher than the prevalence previously indicated 17 , 18 . Levitt et al 18 found that only 36% of patients presented CH 4 levels higher than 1 ppm.…”

Assessment of Exercise-Associated Gastrointestinal Perturbations in Research and Practical Settings: Methodological Concerns and Recommendations for Best Practice

“…(c) Hydrogen production may be reduced because of low colonic pH (Perman et al, 1981). There is a proportion of the population who are occasional nonproducers of hydrogen, which could be related to normal shifts of bacterial flora (La Brooy et al, 1983) measuring methane alongside hydrogen is advocated but the variability of methane production is unknown (Harvie et al, 2019). (d) There is poor reproducibility of lactulose breath testing (Yao & Tuck, 2017).…”

Effects of Prebiotic and Probiotic Supplementation on Lactase Deficiency and Lactose Intolerance: A Systematic Review of Controlled Trials

“…The increase in exhaled H 2 results from the release of gases by heterofermentative bacteria that digest lactose [53]. However, the correlation between lactose malabsorption (or the load of undigested lactose) and LI (presence of symptoms) is not always clear: The HBT is thought to produce 5%-15% false negatives, mainly due to non-hydrogen production and methane production [54][55][56].…”