why are so many people lactose intolerant
Up to 90 percent of South Asians may be lactose intolerant. Lactose intolerance, which is due to the inability to digest milk sugars, is a common disorder caused by a deficiency of the lactase enzyme in the digestive system. Lactose intolerance is three times more common in South Asians than in other populations. 1  Symptoms. 2  Diagnosis.