If you can’t guzzle as much milk as you used to, you may be wondering: Why am I lactose intolerant? Know that you’re not alone: Nearly seven in 10 people develop some degree of lactose intolerance as they get older, according to the National Institutes of Health.
That intolerance can lead to uncomfortable symptoms — such as stomach aches, bloating, diarrhea, nausea, belly rumbling, constipation and gas — that can happen within an hour of eating or drinking dairy products.
If you experience these symptoms, one possible cause could be lactose intolerance. Blame it on lactase. Lactase is an enzyme that helps break down lactose, a sugar found in milk products. If you have enough lactase in the lining of your small intestine, you can consume dairy just fine. If you don’t, lactose tolerance becomes an issue.
“Most people are born with the ability to digest lactose,” said Helen Long, RDN, CDE a registered dietitian at Winchester Hospital in Winchester, Massachusetts. “There’s lactose in breast milk, for example, and most infants can tolerate lactose. But over time, some people will start to develop lactose intolerance and some don’t.”
So what’s the source of your lactose intolerance? It might just be a matter of getting older — or it could link back to one of these six lactose intolerance causes:
If your parents had problems digesting lactose, you might, too. That’s not to say that you’ll have the same level of intolerance — after all, everyone is different. Maybe your dad couldn’t stomach dairy at all, while you can get away with a stick of string cheese — but in general, we tend to inherit the digestive traits of our parents.
Your ethnic background plays a role in your ability to process lactose, too. More than 90 percent of people with certain types of East Asian heritage — it’s especially common among people of Chinese and Japanese descent — are lactose intolerant. It’s also frequently seen in those with Arabic, Italian, West African, Greek or Jewish heritage.
3. Different Types of Dairy
Not all dairy products have equal amounts of lactose. For example, a cup of whole milk has 13 grams of lactose, while two slices of cheddar cheese only has about a quarter of a gram.
So if you drink a lot of milk and have symptoms of lactose intolerance, don’t rush to drop dairy altogether. You can still eat lower-lactose products, like yogurt or cheese.
“It’s not an all-or-nothing condition,” Long said. “Every single person can be different. You may have enough of the lactase enzyme to digest yogurt, but maybe you can’t do yogurt and milk.”
4. Baked Goods
Pastry fans, beware: Lactose doesn’t bake out of bread, so muffins, biscuits or cookies made with milk can still trigger symptoms. If baked goods cause problems, swap a lactose-free milk or an alternative milk into your recipe.
5. Side Effects of Medication
Sometimes, lactose intolerance can come and go with medications that impact the digestive system. If you experience lactose intolerance after taking a medicine, talk to your doctor.
6. Underlying Infections or Diseases
Several underlying problems — like celiac disease, irritable bowel syndrome or gut inflammation — can either trigger lactose intolerance or cause symptoms that are very similar to it. To rule out more serious problems, always check with your doctor.
How to Tell if You Have Lactose Intolerance
If you think that dairy products are what’s giving you trouble, Long recommends a simple test: Drink two glasses of milk on an empty stomach, and then see how you feel over the next few hours.
Beyond that, start a food diary and track how your eating habits affect the way you feel to narrow in on possible lactose intolerance causes.
“I actually ask patients to do that before they come see me,” Long said. “And then we do it again when they’re working with me to zero in on what is causing their symptoms. Sometimes, I’ll also recommend that someone cut out all the potential sources of symptoms, and slowly reintroduce them one at a time. Then, you might notice, ‘Oh, one cup of milk didn’t cause problems, but when I drank that second or third one, that was past my limit.'”
In some cases, your doctor may even recommend another test called a hydrogen breath test to confirm lactose intolerance. In that test, patients breathe into a container that measures the hydrogen content of their air, which can help detect problems digesting lactose.
Treatments for Lactose Intolerance
Good news, dairy lovers: Even if you’re only somewhat lactose intolerant, you don’t have to quit milk and cheese cold turkey. Of course, if you’re highly intolerant, you might want to consider scaling back and choosing lower-lactose products like yogurt or cheese. But keep in mind that you have other options, too.
“You can look for milks that are low in lactose, and there are many varieties on the market now,” Long said. “There are also enzyme tablets that you can get over-the-counter and take right before you eat milk products. They help line your intestinal wall with lactase so that you can digest [milk products] better.”
Just know that if you have a milk allergy, such products won’t help. People often confuse a milk allergy with lactose intolerance, Long says, but the two are very different.
“People with milk allergies are reacting to the proteins in milk, and they can have an anaphylactic shock from drinking it,” she said. “Having a stomachache, while uncomfortable, is very different than an allergic reaction, which is much more dangerous.”
Are you asking yourself: Why am I lactose intolerant? What can I do about it? Connect with a Lahey Health provider and get some answers. Find one near you.