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Lactose Intolerance – What is it?


Lactase is an intestinal enzyme required to cleave lactose into its readily absorbable monosaccharides glucose and galactose [1].Lactose Intolerance occurs when there is a lactase deficiency or the activity of the lactase enzyme is suppressed for whatever reason, resulting in the malabsorption of lactose which is subsequently fermented by colonic bacteria producing gas. The presence of this gas can result in numerous symptoms including: stomach pain, bloating, flatulence, constipation and diarrhoea. If symptoms are experienced then it is considered to be lactose intolerance if gas is detected via a hydrogen-methane breath test but no symptoms are experienced then it is considered to be lactose malabsorption [1].

The breath test is considered to be the preferred method for assessing these conditions due to being relatively inexpensive and non-invasive.  Research has shown that the Hydrogen and Methane breath test for Lactose Malabsorption and Intolerance has the highest accuracy of any of the breath tests when compared to genetic testing with sensitivity and specificity ranging from 76%-94% ,77%-96%, respectively  [1]. In saying this false positive result can still occur. Typically, a false result can occur in the presence of small intestinal bacterial overgrowth (SIBO) [2]. Consequently, a lactu-lose breath test must be completed as a control test at least 2 days before the lactose test to not only indicate the primary gas produced when malabsorption is occurring but also give an indication of oro-caecal transit time and indicate the possible presence of SIBO [3]. If SIBO is considered a possibility then a glucose breath test will be administered to confirm the presence of proximal bowel bacterial overgrowth.

Here at Stream Diagnostics we can help get to the bottom of your symptoms and help determine whether these are caused by a Lactose Malabsorption. If you have further questions about the Lactose Intolerance test, or if it would be right for you, give us a call today!

[1] Yang  JF, Fox M, Chu H, Zheng X, Long YQ, Pohl D, et al. Four-sample lactose hydrogen breath test for diagnosis of lactose malabsorption in irritable bowel syndrome patients with diarrhoea. World J Gastroenterol. 2015 Jun 28; 21(24): 7563-7570.

 [2] Nucera G, Gabriella M, Lupascu A, et al. Abnormal breath tests to lactose, fructose and sorbitol in irratable bowel syndrome may be explained by small intestinal bacterial overgrowth. Aliment Pharmacol Ther. 2005; 21:1391-1395.

[3] Bate JP, Irving PM, Barrett JS, Gibson PR. Benefits of breath hydrogen testing after lactulose administration in analysing carbohydrate malabsorption. Eur. J. Gastroenterol. Hepatol. 2009; 00:000-000.