What is lactose intolerance?
You're lactose intolerant when your intestines lack a certain enzyme, called lactase, needed to digest lactose, the sugar in milk and other dairy products. Within 30 minutes to two hours of eating these foods, you may suffer cramps, gas, bloating, and diarrhea. Unfortunately, you can't reverse lactose intolerance. But by making a few changes in your eating habits or by using lactase tablets and drops, you can usually treat the symptoms well enough to enjoy your favorite ice cream or cheese. And, because most dairy products are so rich in calcium, you'll have an easier time getting enough of the mineral to keep your bones and teeth strong.
How many people are lactose intolerant?
For 30 to 50 million Americans, a big glass of milk can bring on the distressing symptoms of lactose intolerance. The condition is so common--and so natural--that some doctors don't even like to call it a disorder. That's because many of us naturally lose the ability to digest lactose as we grow into adulthood. Your ethnicity seems to play a role, too: As many as 90 percent of Asian Americans and 75 percent of African Americans and Native Americans are lactose intolerant. At 20 percent, Caucasians are least likely to be affected.
How do I know if I'm lactose intolerant?
You might be if you have stomach pain and gas after eating milk or dairy products. Try this: Stop eating them for a few days and see if your symptoms go away. Then eat the same foods again; if the pain and gas return, take some of the practical steps below. Note that diagnosing your own lactose intolerance can be tricky. Some people mistake their symptoms for lactose intolerance when they have another condition, such as irritable bowel syndrome.
If you're not sure, your doctor can perform tests to nail down a diagnosis. One test calls for you to fast (go without eating) and then drink something containing lactose. Afterwards, your blood sugar level is measured to see how well you digested the lactose. Another test measures the amount of hydrogen in your breath after you drink a lactose-loaded beverage. High levels of hydrogen indicate that you are not digesting lactose efficiently. For infants and small children, doctors will measure the amount of acid in their stool to determine how well they are digesting lactose.
Is lactose only in dairy products?
No. In fact, it's in many prepared foods, and even a little can kick up your symptoms. Lactose is included in some breads, processed breakfast cereals, instant potatoes, soups, margarine, lunch meats, pancake mixes, cookies, and powdered coffee creamers (even some labeled nondairy). To sniff out lactose, scan labels for these ingredients: milk, lactose, whey, curds, milk byproducts, dry milk solids, and nonfat dry milk powder.
Check your medicine cabinet, too. Lactose is the base for more than 20 percent of prescription drugs and about 6 percent of over-the-counter medicines, although these products usually only affect people with severe lactose intolerance. Some common drugs include many types of birth control pills and tablets for stomach acid and gas (some people take antacids as calcium supplements, and some, but not all, contain small amounts of lactose--check the label or ask your pharmacist). Ask your pharmacist whether medications you take regularly contain lactose.
What are my treatment options?
- Adjust your diet. At first, instead of cutting out dairy altogether, take milk and dairy products in smaller doses. Adults who think they're lactose intolerant may still be able to eat small amounts without discomfort. Instead of downing a full glass of milk, try just 4 to 6 ounces--about half to three-quarters of a measuring cup. Just don't go over a total of 8 ounces, or a full cup, in one day. As the dose of lactose goes up, so does the frequency and severity of symptoms. Learn through trial and error how much lactose you can handle. For children, however, the above approach may not work so well--and may even be harmful. While older children also may be able to handle small amounts of dairy, young children who are lactose intolerant shouldn't consume any milk or dairy products. They could get a bad case of diarrhea, which may lead to dehydration. If your child seems lactose intolerant, talk to your pediatrician. The answer may be as simple as putting your child on a substitute, such as soy formula or soy milk.
- When it comes to lactose, not all dairy products are created equal. Some have less lactose than others, such as hard cheeses (cheddar and Swiss are good bets) and yogurt (check the label for live or active cultures).
- Have milk or dairy products with a meal. The mix of foods slows the release of lactose into your digestive system, so you reduce your chances of discomfort.
- Buy lactose-free milk, which you can find at supermarkets. Or add over-the-counter lactase enzyme drops to regular milk, which reduce lactose by 70 to 90 percent. Let the drops work for 24 hours before you drink the milk. These drops work well and allow many people to keep milk in their diet so they get plenty of calcium and a host of other nutrients as well: protein, vitamins A and D, riboflavin, magnesium, and phosphorus.
- Take over-the-counter lactase enzyme tablets at the beginning of a meal to help your body digest solid foods that contain lactose. Some tablets come in chewable form. Like the drops above, these pills are safe and work well.
- If you find you can handle only a little dairy, or if you're just not able to eat any, you'll want to make sure you get enough calcium. Work these foods into your diet regularly: broccoli, kale, collard greens, canned salmon with bones, calcium-fortified orange or grapefruit juice, soy milk, and tofu processed with calcium sulfate. All are rich in calcium.
Levitt MD, et al. A commonsense approach to lactose intolerance. Patient Care April 15, 1997;31(7):185-7.
Suarez FL, et al. A comparison of symptoms after the consumption of milk or lactose-hydrolyzed milk by people with self-reported severe lactose intolerance. NE J Med July 6, 1995;333(1):1-4.
Suarez FL, et al. Tolerance to the daily ingestion of two cups of milk by individuals claiming lactose intolerance. Am J Clin Nutr 1997 May;65(5):1502-06.
National Digestive Diseases Information Clearinghouse. Lactose Intolerance. March 2006.
National Institutes of Health. What People with Lactose Intolerance Need to Know About Osteoporosis. January 2009.