Lactose maldigestion – also called lactose intolerance – happens when your body doesn’t have enough of a special digestive enzyme known as lactase. You need this enzyme to break down lactose, the carb found in milk. If you find that drinking milk always upsets your stomach or gives you gas, cramps or other embarrassing or painful digestive problems, lactose intolerance might be what’s troubling you.
For most people around the world, lactase levels naturally go down once they are past the stage of drinking a milk-rich diet -- that is, once they grow out of infancy and early childhood. Although some can continue to produce enough lactase after this point to fully digest milk, a subset of the population – between 30 and 50 million Americans, according to the Cleveland Clinic – no longer manufacture enough lactase to be able to drink milk without unpleasant digestive symptoms. Among some ethnic groups, such as African Americans, Native Americans and Asian Americans, between 75 and 90 percent are lactose intolerant.
Lactose maldigestion causes a host of gastrointestinal problems, and symptoms can be painful and embarrassing. Between 30 minutes and two hours after drinking milk, you may experience nausea, abdominal bloating, stomach pain, gas and diarrhea. These symptoms happen because, even though you can’t digest the lactose in the milk you drink, the bacteria in your gut can. As they break it down in your intestines, they create the gas that causes your digestive upset. How bad your symptoms are can depend on how much milk you drink; if your body produces small amounts of lactase, you might be able to tolerate a small glass of milk but not an extra-large latte.
You can cope with lactose intolerance in several different ways. Commercially available lactose-free or reduced-lactose milk is made with milk that’s had the enzyme lactase added to it. You can also take lactase supplements before drinking milk to add the enzyme to your system. Consuming milk with a meal, rather than on its own, can help reduce or avoid nasty symptoms, and building up your tolerance to lactose by gradually including more milk in your diet can sometimes build up the level of lactase in your digestive system.
Because milk and milk products are such good sources of calcium, it’s helpful to find ways to include them in your diet rather than to just eliminate them, even if you are lactose intolerant. Besides adding lactase through commercial products, you can select dairy foods that are rich in calcium but relatively low in lactose, such as Swiss or cheddar cheese. You can include yogurt in your diet, because, even though it contains lactose, the lactose in yogurt is more easily digested than that in milk. Non-dairy foods can also supply calcium to your diet. Rhubarb, spinach and canned sardines or salmon with bones can bump up your calcium intake.
- National Institute of Diabetes and Digestive and Kidney Diseases: Lactose Intolerance
- Journal of the American College of Nutrition: Lactose Maldigestion, Calcium Intake and Osteoporosis in African-, Asian-, and Hispanic Americans
- Dairy Council of California: Lactose Intolerance
- Cleveland Clinic: Lactose Intolerance
A writer since 1985, Jan Annigan is published in "Plant Physiology," "Proceedings of the National Academy of Sciences," "Journal of Biological Chemistry" and on various websites. She holds a sports medicine and human performance certificate from the University of Washington, as well as a Bachelor of Science in animal sciences from Purdue University.