Between 30 and 50 million Americans produce insufficient amounts of the enzyme (lactase) needed to digest lactose, the naturally occurring sugar in milk. Rather than being broken down and absorbed, lactose gets trapped in the digestive tract, which can cause nausea, gas and diarrhea; usually within 30 minutes to two hours of eating. Unpleasant stuff. Avoiding milk spares you (and the ones you love) those unpleasant side effects; however, that also narrows down bone-building calcium and vitamin D food choices. Thankfully, there are more options now than ever. Lactose intolerants can drink Lactaid, which is "regular" cow's milk with lactase added. Or try "milks" made from soy, rice or almonds. Choose those fortified with 25 to 30 percent of the daily value for both calcium and vitamin D per cup. Many with lactose intolerance can enjoy cheeses (particularly aged ones) and yogurts symptom-free, because much of the lactose is removed during processing. But if these foods cause trouble, you can try nondairy (e.g., soy) versions. They usually don't mimic dairy-based products in taste or nutritional value; some come close on texture. Eating more of nondairy foods that supply good amounts of vitamin D (e.g., mackerel) and calcium (e.g., kale, almonds) also will help you meet your needs for these nutrients.