Are you really lactose intolerant?

There is a difference between lactose intolerance and casein allergy or sensitivity

Some people can still have limited dairy with lactose intolerance -- but not with casein allergy

You can still get calcium in your diet without dairy products

You drink a glass of milk and your stomach feels upset, or a scoop of ice cream leaves you with a congested nose. You assume that you, like 30 million to 50 million other Americans, are lactose intolerant. But are you really? That depends on your specific symptoms.

"Lactose sensitivities are well known, but people may not be as familiar with casein allergies or a sensitivity to casein, which can also be experienced when eating or drinking dairy products," says Tawnya Dorn, RD, CDE, a registered dietitian and certified diabetes educator at Queen of the Valley Medical Center, in Napa, California. "They share some similarities in how they affect your body, but there are also some important distinctions between them."

Lactose vs. casein

Lactose is a natural sugar found in products made with milk. Casein is a protein in milk.

Lactose intolerance

If you are lactose intolerant, it means your small intestine can't properly digest lactose after eating or drinking a dairy product. That's because your body doesn't produce enough lactase, the enzyme responsible for lactose absorption. This can be a genetic condition, or it can be caused by a gastrointestinal health issue. 

Some people can have a small amount of dairy and not experience any problems, while others cannot handle any dairy. There are several symptoms indicative of lactose intolerance, and the severity of each can vary depending on how much milk you consume and your tolerance level. They include gas, bloating, diarrhea, abdominal pain, nausea and vomiting.

Casein allergy or sensitivity

Problems with casein differ from lactose intolerance. If your body can't handle casein, that can be considered a milk allergy, and consumption of casein triggers an allergic reaction, with symptoms such as a skin rash or hives; swollen lips, mouth or tongue; and runny nose and watery, itchy eyes. In severe cases, it can cause anaphylaxis, which can be a fast-moving, life-threatening allergic reaction if not treated immediately. There can also be some of the symptoms that come with lactose intolerance, such as bloating and stomach pain.

Milk allergies such as casein allergy generally are diagnosed early in life and don't suddenly appear in adulthood. Unlike people with lactose intolerance who may be able to consume dairy in limited quantities without a problem, if you have a casein allergy you should avoid milk and milk products entirely.

Dietary notes

If you can't consume dairy because you are lactose intolerant, there are still plenty of dairy-free versions of common foods, such as milk alternatives or lactose-free yogurt. Some cheeses, such as cheddar, are naturally low in lactose. If you have a casein allergy, it's a little trickier, as many packaged foods — ranging from salad dressings to breads to cereals — can contain milk solids, which can include casein. It's best to talk with your health care professional about the proper diet for a casein allergy.

Dorn says you shouldn't necessarily worry about a milk intolerance or allergy getting in the way of your daily calcium intake. "It is important for bone health to get enough calcium, and a diet of healthy, whole foods can help you meet your calcium goals without any dairy at all," Dorn says. "There are plenty of foods out there, including dark leafy green vegetables, white beans, black-eyed peas, sardines, almonds and tofu that are good sources of calcium and many other beneficial nutrients."

Need help with food allergies? Find a skilled Providence St. Joseph Health physician near you. Subscribe to our blog and get the best of To Your Health delivered to your inbox.

This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.