How Bad Is It Really to Eat Dairy if You're Lactose Intolerant?

You know dairy doesn't sit well with you, but sometimes it's so hard to resist: the melty ice cream cone on a sweltering summer day, the gooey grilled cheese dunked in creamy tomato soup, the mouth-watering slice of camembert at a cocktail party. Mmmm!

So what happens if you ignore lactose intolerance and indulge in a dairy craving? Aside from sentencing yourself to extra time on the toilet that night, could it cause lasting damage to your GI system?

First, breathe a sigh of relief: The side effects stink, but they're not harmful. What's more, there are measures you can take to avoid or mitigate them. Turns out it ‌is‌ possible have your gelato and eat it too.

Lactose intolerance is super common. According to the National Library of Medicine, approximately 65 percent of people have a reduced ability to digest lactose after infancy.

"The small bowel contains enzymes that help us break down food," says Shaham S. Mumtaz, MD, gastroenterologist at North-western Medicine Central DuPage Hospital. "One of these enzymes is lactase, which helps break down the sugar lactose so that your body can absorb it."

People with lactose intolerance don't produce much or any lactase, which leads to unpleasant symptoms. Extra fluids are pulled into your small bowel, causing diarrhea and cramping. Instead of enzymes, gut bacteria break down lactose, producing foul-smelling gas and bloating along the way.

There are a few different triggers driving lactose intolerance. While some people are born with it, other times it develops with age. Milk-guzzling babies tend to produce lactase, but as you get older and consume less milk, your body may transition to making less. "In some cases, an infection might cause your body to stop making lactase," Dr. Mumtaz says. "Very rarely, another disease, such as celiac, can lead to lactose intolerance."

Luckily, the vast majority of folks will only suffer short-term intestinal distress. "Once the lactose passes through your system, you will be perfectly fine," Dr. Mumtaz says.

Does it ever lead to lasting damage? "In less than 1 percent of people — such as those who have a milk protein allergy — eating dairy can have long-term effects," Dr. Mumtaz says. "In these extremely rare instances, lactose causes inflammation of the small bowel tissue that can prevent your body from absorbing vital nutrients."

If you can't avoid dairy completely, it's helpful to opt for products labeled "lactose-free." "These products have been treated with lactase enzymes ahead of time to make sure they don't contain any actual lactose," Dr. Mumtaz says. "This makes it easier to avoid or reduce symptoms."

Or choose products made with a milk replacement, like oat, coconut, soy, rice or nut milk.

You can also take a medication like Lactaid ($15.54, Amazon) at the same time or shortly after consuming dairy. "Lactaid contains the lactase enzyme your body is lacking," Dr. Mumtaz says. "It will help break down lactose into sugars that your body can actually absorb."

Or just savor a mini portion of your favorite dairy product. A June 2020 study in the ‌Journal of Translational Medicine‌ found that the vast majority of people who are lactose intolerant can consume up to 5 grams of lactose (equivalent to about a half cup of milk) without ill effect.

The study also revealed that most lactose intolerant people can eat yogurt (especially plain yogurt) without symptoms.

When you do have dairy, eat it along with a meal. This may lead to fewer problems, according to Johns Hopkins Medicine.

So you slipped up and got your dairy on. What now? "Take an over-the-counter lactase enzyme replacement as soon as you can to mitigate the worst of the symptoms," Dr. Mumtaz says.

But don't be surprised if you still have some breakthrough GI issues. "Depending on how much dairy you ate, the amount of the enzyme may not be enough to break down all the lactose," Dr. Mumtaz says. "It also depends on timing — if you wait too long and the dairy has already moved through a good portion of the bowel, you may not get as much of a desired effect."

Although it varies from person to person and depends on the amount of dairy you take in and how quickly your small bowel moves, lactose intolerance symptoms typically last less than 12 hours, and about four to six hours for most folks.

"People who are born with lactose intolerance tend to experience more symptoms," Dr. Mumtaz says. "Those whose lactose intolerance is caused by an infection can usually still get away with eating some amount of dairy."

One more thing to keep in mind: Some people mistake irritable bowel syndrome (IBS) for lactose intolerance. "If other foods besides dairy are causing you intestinal issues, it might be IBS," Dr. Mumtaz says. "In that case, talking to your primary care doctor or a gastroenterologist may be helpful in figuring out treatments that could improve your quality of life, such as supplements or diet modifications."

It's really not that bad. "You are not doing yourself any long-term harm," Dr. Mumtaz says. "If it's worth it to you to enjoy dairy despite the aftermath, then go for it."