Small Intestinal Bacterial Overgrowth (SIBO) Breath Test – Lactulose
At-home breath tests can help determine some of the causes of digestive distress. Small intestinal bacterial overgrowth (SIBO) occurs when intestinal bacteria overgrow in the small intestine (Bures 2010; Dukowicz 2007; Bayeli 1999). This overgrowth can lead to excess production of gas and bacterial metabolites, causing bloating, flatulence, diarrhea, constipation, and cramping (Sachdev 2013). Lactulose has the advantage of detecting bacterial overgrowth throughout the small intestine, including the lower end where it more commonly occurs. Humans cannot digest or absorb lactulose, and only bacteria have the proper enzymes to break it down (Chen 2012). Lactulose passes unabsorbed through the normal small intestine, and when it reaches the colon, it is metabolized by bacteria to gases, including hydrogen, which can be detected (Simren 2006; Saad 2014).
Small Intestinal Bacterial Overgrowth (SIBO) Breath Test – Glucose
Although glucose is highly fermentable by bacteria, it is typically absorbed in the upper portion of the small intestine and thus, SIBO existing in the lower portion of the small intestines may be missed (Mattsson 2017; Chen 2016; Kiela 2016). The glucose breath test is more accurate than the lactulose breath test, and is considered more acceptable for diagnosing SIBO (Enko 2016; Rana 2014; Ghoshal 2011; Saad 2014). The test can also give false-positive results if the oral bacteria flora produces hydrogen (Mattsson 2017).