Are you thinking of breaking up with milk and ice cream because you’re convinced you’re allergic to dairy…or are lactose intolerant? Before you steer your shopping cart away from the dairy aisle forever, let’s get the terms straight. Lactose intolerance is not the same as milk allergy, and what works for one won’t necessarily work for the other. Here’s what you need to know.


Lactose is a sugar that’s present in cow’s milk. People with lactose intolerance have low levels of lactase, an enzyme that helps digest lactose. If your body doesn’t make enough lactase, your morning bowl of cereal with milk, that pizza you have at lunch or the bowl of ice cream for dessert can leave you bloated, gassy and experiencing constipation or diarrhea…or both.

Who has lactose intolerance? Mostly adults—and, indeed, most adults. Worldwide, about 65% of adults lose all or some of their ability to digest lactose in adulthood. In these people, the ability to produce lactase declines gradually throughout childhood and adolescence, so symptoms usually don’t occur until adulthood. There’s a strong genetic component: 90% of adults of East Asian descent are lactose intolerant, and the condition is prevalent in African-Americans, other Asian Americans, Hispanics, Native Americans and people of Arab, Jewish, Greek and Italian descent. The exception: Only 5% of people of Northern European descent are lactose intolerant.

How do you know you have it? Most people with lactose intolerance easily pinpoint some or all of the above symptoms between 30 minutes and two hours after consuming dairy. If you want to be a little more scientific about it, keep a food diary to track your symptoms—record what you eat and when and then how you feel over the next couple of hours. Still not sure? Your doctor can give you a breath test for a definitive diagnosis of lactose intolerance.

What’s the health risk? You might think that people with lactose intolerance would be more prone to osteoporosis because they avoid calcium- and vitamin-D–rich foods. The good news is that research hasn’t found this link to osteoporosis to be true. Still, if you can’t digest most dairy foods, you need to consume alternative sources of these nutrients, such as soy milk fortified with calcium and vitamin D.

What can you do about lactose intolerance? Not everyone with lactose intolerance has to eliminate dairy…it depends on your symptoms. You can try an elimination diet—cut out all dairy for two to four weeks, then gradually reintroduce small amounts to see how much and what types you can handle. You might also try consuming low-lactose milk and other dairy products that have had lactose reduced…adding a lactase supplement to your diet to help you digest lactose-containing dairy foods…eating dairy products in combination with other foods…or enjoying naturally lower-lactose dairy, such as hard cheeses and yogurt. Bonus: Eating fermented dairy foods with active live cultures, including yogurt and kefir, has an added benefit—the lactose-digesting bacteria may last for weeks in the gut, helping you digest other dairy foods like milk or ice cream.


A true milk allergy means your immune system reacts to specific proteins in milk, especially casein, as though they are harmful invaders. The defense an allergic person’s body mounts against the misidentified “enemy” triggers symptoms ranging from the mild, such as diarrhea, stomach cramps or hives, to more severe—indeed, potentially fatal—such as swelling in the throat and difficulty breathing.

Who has milk allergy? Allergy to cow’s milk is most often seen in babies and children and is often outgrown. Infants may have an allergic reaction to a milk-based formula, and even strictly breastfed babies can have an allergic reaction to cow’s milk proteins that enter breast milk through the mother’s diet.

How do you know you have it? Via allergy testing, such as a skin or blood test. If you suspect your baby has a milk allergy, take the child to a pediatric allergist for testing.

Can adults have a milk allergy? Yes—in fact in one study, more than half of adult patients who had problems digesting dairy foods in spite of being on a low-lactose diet tested positive for milk allergy. If you have trouble digesting dairy foods, and a breath test shows that you don’t have lactose intolerance, ask your doctor to test you for a milk allergy.

What can you do? In the case of a true allergy, you (or your child, more likely) will have to avoid all dairy products and foods containing them until the allergy is outgrown—or permanently if it is not outgrown.