I could be lactose intolerance (a breath test will tell) and that can be fixed with taking Lactaid. For many IBSers, though, the fat in esp. whole milk can be another source to irritate the colon/GI system. So, even though some people are not lactose intolerate, they still find milk irritating. Yogurt is better b/c it's fermented and some may also have live cultures of probiotics to help make it easier.For the cereal, it may also depend on what other ingredients it has. For example, high sugar level, esp. artificial sweeteners, tend to bother IBSers.