There’s a lot of confusion surrounding lactose intolerance and milk allergy — the terms may sound similar, but they actually describe two different digestive problems, and one is more severe than the other.
Lactose intolerance is caused by not having enough of the enzyme lactase, which is needed to break down lactose, the sugar found in milk and other dairy products. Milk allergy is a true food allergy caused by an allergic reaction to the protein in milk.
“Lactose intolerance and milk allergy are very different entities,” explains Amy E. Barto, MD, a gastroenterologist at the Lahey Clinic in Burlington, Mass. “Milk allergy usually shows up early in life. Lactose intolerance is more common, takes longer to develop, and can occur at any time of life.”
Symptoms of Lactose Intolerance vs. Milk Allergy
Lactose intolerance can be genetic, or it can be caused by damage to the small intestine due to a viral or bacterial infection, Dr. Barto explains. It’s also fairly common, and more so in certain populations. “About 80 to 90 percent of African-Americans have lactose intolerance, and it is also very common in Asians and Native Americans,” says Barto. “It is also important to remember that lactose intolerance increases with age and is quite common in the elderly.”
It’s estimated that 30 to 50 million Americans have lactose intolerance.
You’ll typically feel lactose intolerance symptoms between 30 minutes and two hours after ingesting milk or a dairy food. Symptoms may include:
•Gas and bloating
Milk allergy usually refers only to cow’s milk, although you may also be allergic to other types of milk, including soy. Although milk allergy is most common in infants and children, it can develop at any age. Milk allergy is the most common food allergy in children, affecting more than 2 percent of children who are under the age of 3. Many children outgrow milk allergies by age 5.
The food allergy reaction to milk can begin within minutes or can be delayed for several hours. Symptoms may include:
•Swelling of the lips or throat
Diagnosing Lactose Intolerance and Milk Allergy
Lactose intolerance can typically be distinguished from milk allergy by less severe symptoms and a person’s history of problems with dairy, but sometimes doctors aren’t able to differentiate the two right away. “Your doctor may ask you to keep a food diary, avoid dairy for a while, and then reintroduce it,” says Barto. “If in doubt, there are lab tests that can help make the diagnosis.”
• Hydrogen breath test. Undigested lactose produces high levels of hydrogen gas in your breath. Doctors can diagnose lactose intolerance by measuring this hydrogen after you drink a lactose-loaded beverage.
• Stool acidity test. Undigested lactose also increases the amount of acid in the stool. Doctors may use this test to diagnose lactose intolerance in young children.
• Food allergy testing. If your doctor suspects a milk allergy, you may be sent to an allergist for skin testing or have a blood sample drawn for laboratory allergy testing.
Can You Eat Dairy With Lactose Intolerance or Milk Allergy?
For both of these conditions, you’ll need to avoid or limit most dairy products.
“But it is important to make sure you are getting enough calcium,” says Barto.
If you have lactose intolerance, you may be able to tolerate small amounts of dairy. You can try hard cheeses and yogurt products, which tend to be lower in lactose than milk. There are also a variety of dairy-free foods that are high in calcium, including spinach, almonds, and dark leafy green vegetables.
If you have milk allergy, you need to read labels and avoid foods that have any dairy, including the ingredients casein, whey, lactulose, lactalbumin, and ghee.
If you or your child has symptoms that may be due to milk allergy or lactose intolerance, talk with your doctor. He or she can diagnose the problem and advise you on how best to avoid dairy while maintaining good nutrition, which is important no matter how young or old you are.