A: Milk can sometimes trigger IBS, that's why you'll find dairy on the list of foods to initially avoid. But sensitivity to dairy foods is most commonly a sign of lactose intolerance. Lactose intolerance is not IBS. In fact, it's a completely different problem and one that's easily remedied.
What is lactose intolerance? Milk products contain a form of natural sugar called lactose. In order to digest lactose, our bodies produce a specific enzyme called lactase. For a variety of reasons, including genetics, digestive disorders, intestinal injury, and/or the natural aging process, some people end up with very low levels of lactase. Depending on how much of the offending food you eat, and how much lactase enzyme your body can produce, symptoms can be mild or severe, and include nausea, cramping, gas, bloating, and diarrhea. Sound familiar? The symptoms can be remarkably like IBS symptoms. So, how do you tell the difference?
If you suspect you're lactose intolerant, make dairy the first thing you test. Avoid milk and anything containing milk for three to five days (see my list of Common IBS Trigger Foods). If your symptoms disappear completely, you're most likely lactose intolerant. If you want a definitive diagnosis, you can ask your doctor about taking a Hydrogen Breath Test. This simple test looks for a higher-than-normal amount of hydrogen in the breath, caused by the extra gases produced by the bacteria fermenting the undigested lactose in the intestines. Fortunately, many people with lactose intolerance can enjoy hard, aged cheeses (like cheddar and Swiss), which have insignificant amounts of lactose, as well as lactose-reduced milk products, without any symptoms. You can also take lactase enzyme in a tablet or liquid form with your first bite or sip of a milk product and voilà — no digestive trouble.
If you test positive for lactose intolerance and avoid all milk products but still have gastrointestinal symptoms, it’s possible that you have both lactose intolerance and IBS.