Dietary and biological factors influencing lactose intolerance

The number of Americans affected by lactose intolerance is estimated to be between 30 and 50 million people (NDDIC, 2005). Lactose intolerance is the symptoms experienced when the dose of lactose exceeds the digestive capacity of intestinal lactase (lactose maldigestion). Symptoms of intolerance typically include stomach discomfort, excessive flatulence and soft stool or diarrhea and are dependent on dose of lactose, transit time (influenced by meal composition), and colonic flora adaptation. Modest doses of lactose consumed with a meal on a regular basis are often very well tolerated. Lactose maldigestion may be caused by primary (most common), secondary, or congenital lactase non-persistence. Lactose maldigestion should not be thought of as a disease and is not a reliable indicator of lactose intolerance. The hydrogen breath test has become the most reliable method to diagnose lactose maldigestion. (C) 2011 Elsevier Ltd. All rights reserved.