Lactose intolerance is when someone has trouble digesting lactose, a type of sugar found in milk and other dairy foods.
If people with lactose intolerance eat dairy products, the lactose from these foods pass into their intestines, which can lead to gas, cramps, a bloated feeling, and diarrhea.
Some people can have small amounts of dairy without problems. Others have a lot of stomach trouble and need to avoid all dairy products. Many foods, drinks, and digestive aids are available to help manage lactose intolerance.
What Happens in Lactose Intolerance?
Normally, when we eat something containing lactose, an enzyme in the small intestine called lactase breaks it down into simpler sugar forms called glucose and galactose. These simple sugars are then absorbed into the bloodstream and turned into energy.
In lactose intolerance, the body doesn't make enough lactase to break down lactose. Instead, undigested lactose sits in the gut and gets broken down by bacteria, causing gas, bloating, stomach cramps, and diarrhea.
Lactose intolerance is fairly common. Kids and teens are less likely to have it, but many people eventually become lactose intolerant in adulthood. Some health care providers view lactose intolerance as a normal human condition and not a disease or serious health problem.
Besides age, people can become lactose intolerant due to:
Ethnic background. People of Asian, African, Native American, and Hispanic backgrounds are more likely to develop lactose intolerance at a young age.
Other problems with the digestive tract. People who have inflammation of their upper small intestine, such as celiac disease or Crohn's disease, have less of the lactase enzyme.
Medicines. Some antibiotics can trigger temporary lactose intolerance because they affect how the intestine makes lactase.
Infection. After a bout of infectious diarrhea, some people can develop a temporary lactose intolerance that usually improves after a few days or weeks.
What Are the Signs & Symptoms of Lactose Intolerance?
Lactose intolerance can cause a variety of symptoms. It all depends on how much dairy or milk-containing foods people consume and how little lactase their body makes.
Usually within 30 minutes to 2 hours after eating, someone with lactose intolerance will have:
How Is Lactose Intolerance Diagnosed?
If you might have lactose intolerance, the docto will ask your symptoms and diet. They might test the breath for hydrogen levels before and after you drink lactose. Normally very little hydrogen gas is detectable in the breath. But undigested lactose in the colon breaks down and makes various gases, including hydrogen.
If you have a hydrogen breath test, you'll blow into a tube for a beginning sample. Then you'll swallow a drink with lactose in it, wait a while, and breathe into the tube again. You'll blow into the tube every half hour for 2 hours to measure hydrogen levels. The levels should go up over time if you have lactose intolerance.
Doctors also can find out if someone can digest lactose by testing for the presence of lactase with an endoscopy. During this procedure, doctors view the inside of the intestines by inserting a long tube with a light and a tiny camera on the end into the mouth.
A doctor can then take tissue samples and pictures of the inside of the gut. The amount of lactase enzyme can be measured in one of these tissue samples.
How Is Lactose Intolerance Treated?
People can manage lactose intolerance by not drinking as much milk and eating fewer dairy products. Most can eat a small amount of dairy. But they need to eat it with other foods that don't contain lactose and not eat too much dairy at once.
You may find that other dairy products, such as yogurt and cheeses, are easier to digest than milk. Lactose-free milk is also a great way to get calcium in the diet without the problems. It can also help to keep a food diary to learn which foods you can or can't tolerate.
A lactase enzyme supplement can help too. Taking this before you eat foods that contain dairy helps your body digest the lactose sugar in dairy and prevent pain, cramping, bloating, gas, and diarrhea.
What About Calcium?
Dairy foods are the best source of calcium, a mineral that's important for bone growth. Because teens need about 1,300 milligrams (mg) of calcium each day, experts recommend that even those with lactose intolerance include some dairy in their diet.
You also can eat non-dairy products like:
calcium-fortified juice or soy milk
green, leafy vegetables like broccoli, collard greens, kale, and turnip greens
Talking to a registered dietitian is a good idea. They're trained in nutrition and can you come up with eating alternatives and develop a well-balanced diet that provides lots of calcium for developing strong bones. Some teens might need calcium and vitamin D supplements.
What Else Should I Know?
Here are some tips for dealing with lactose intolerance:
Choose lactose-reduced or lactose-free milk.
Take a lactase enzyme supplement (such as Lactaid) just before you eat dairy products. These can be taken in drops or tablets and even added directly to milk.
When you do drink milk or eat lactose-containing foods, eat other non-lactose foods at the same meal to slow digestion and avoid problems. (For example, if you are going to have a milkshake, don't drink it by itself. Have something else with it, like a healthy sandwich.)
Drink juices that are fortified with calcium.
Eat a variety of dairy-free foods that are rich in calcium, such as broccoli, beans, tofu, or soy milk. Consider hard cheeses such as cheddar, which are lower in lactose.
Yogurts that contain active cultures are easier to digest and much less likely to cause lactose problems.
Learn to read food labels. Lactose is added to some boxed, canned, frozen, and prepared foods like bread, cereal, lunchmeats, salad dressings, mixes for cakes and cookies, and coffee creamers. Be aware of certain words that might mean the food has lactose in it: butter, cheese, cream, dried milk, milk solids, powdered milk, and whey, for example.