What is the role of lactose intolerance?
Lactose intolerance can cause symptoms similar to those associated with IBS. The prevalence of lactose intolerance is slightly higher in adults with IBS; however, lactose intolerance is not the cause of IBS in most patients. Nevertheless, because of the similarity in symptoms, patients with symptoms suggestive of lactose malabsorption should be given an empiric trial of a lactose-free diet or a lactose hydrogen breath test, which measures the exhaled hydrogen produced from colonic bacterial degradation of lactose.
Patients who respond to a lactose-free diet should be encouraged to gradually reintroduce lactose into their diet to determine if and when symptoms recur. Most people with lactose intolerance can consume up to 1.25 cups (280 mL) of milk per day without significant symptoms. Avoidance of lactose can lead to significant reduction in calcium intake, which may increase the risk of osteoporosis. Therefore patients on a restricted lactose diet should be advised to increase their calcium intake from other sources. Live-culture yogurt is another alternative source of calcium that is well tolerated by many patients with lactose intolerance.