Normally there is a peak in hydrogen production two hours after lactulose ingestion, reflecting the passage of this non-absorbable carbohydrate into the colon. Vigorous exercise, smoking or sleeping should be avoided immediately before, or at any time during the test. The patient should not have eaten slowly digesting foods such as beans and bran on the day before the test and should have fasted for 14 hours prior to the test, with only water to drink. Methane also appears to slow down the passage of food through the intestinal tract.

Recent work has demonstrated that among IBS subjects, methane production in the lactulose breath test is associated with constipation. Methanogenic bacteria are independent of hydrogen-producing bacteria so methane determination along with the measurement of hydrogen is thus required in the study of lactose intolerance and in other carbohydrate breath tests.īreath testing to aid in the diagnosis of small intestinal bacterial overgrowth (SIBO) may also provide a framework for the understanding of irritable bowel syndrome (IBS). In the same study, out of 13 subjects with a false negative breath hydrogen response to lactulose, 11 subjects had a methane percentage increase greater than 100%. It was also reported that, in 34% of lactose intolerant patients with a negative hydrogen breath test, the methane percentage increase after a lactose challenge was greater than 100%. According to research from the 1970s, which was repeated in 2006, approximately 35% of healthy adult subjects are methane producers. These tests are safe alternatives to more invasive procedures such as biopsy. The sole source of these gases in alveolar air is bacterial fermentation of carbohydrate in the gut, so estimation of hydrogen and methane in breath samples can be used to study the passage of carbohydrates through the gut and the presence of pathogenic bacteria in the gastro-intestinal lumen.īreath tests can be helpful in the evaluation of bloating, diarrhoea, constipation and malabsorption. The basis for breath testing in these circumstances is that bacteria in the intestine can break down carbohydrates to produce hydrogen and methane. The syndrome is difficult to diagnose with accuracy using blood tests.

Small intestinal bacterial overgrowth (SIBO), as it is known, is characterized by steatorrhea and diarrhoea, together with vitamin deficiencies and carbohydrate malabsorption. Structural or functional disorders of the gastrointestinal tract can lead to bacterial overgrowth in the small intestine, with colonic bacteria proliferating in the ileum and jejunum. Normally the human small intestine contains fewer bacteria than the colon. Biolab follows protocols for breath hydrogen and methane testing that are in line with current practice in Europe and America.

Bacterial overgrowth test