Many people with celiac are told they have IBS by their doctors. Celiacs have an autoimmune reaction to gluten, (wheat, rye, barley, and oats for some). The autoimmune attack destroys the villi in the small intestine that produce the lactase (enezyme that digests lactose sugar in milk). So lactose intolerance is a fairly common condition with celiac. Celiacs also tend to develop intolerances to other foods due to the irritation of the gut. They also get a myriad of other symptoms because of the mal-absorption of nutrients from foods etc.