Lactose intolerance: you probably have it

Experiencing gastrointestinal (GI) symptoms such as abdominal pain, diarrhea or bloating with dairy products - known as lactose intolerance - is incredibly common. Although the latest guidelines don't describe what percentage of the U.S population has these symptoms, the numbers are high.


What is lactose intolerance?

Lactase is the enzyme in your gut that allows you to break down dairy products with ease. Humans lose 95% of their lactase levels by early childhood, so most adults have some form of lactose intolerance. Your likelihood of having it depends on race: the numbers are as high as 20% if you're White, 70% if you're Indian, 80% if you're Hispanic, Black, or Jewish, and up to 100% if you're Asian or Native American.

If those numbers seem high, it's because the term lactose intolerance, although used colloquially to describe anyone with sensitivity to dairy, really refers to a spectrum with three categories (in order of severity):

  1. Lactase deficiency: you can still digest dairy products, but the amount of lactase in your gut is relatively low to where you still experience symptoms with high intake
  2. Lactose malabsorption: the majority of dairy you digest causes symptoms and only in very small quantities are you unaffected
  3. Lactose intolerance: complete and total intolerance to any dairy products, with any amount you ingest resulting in abdominal pain, gas, and/or diarrhea


Why does dairy cause GI symptoms?

For a refresher on how your gut works, check out our article on GI basics. It's your small intestine's job to digest and absorb the nutrients from the food you eat. It does this by using the enzyme lactase to break down lactose into a digestible form. If there's not enough lactase, that lactose moves onto the colon where rather than digest it, your colon will either move water into the gut to flush it out (aka diarrhea) or bacteria will get rid of it through fermentation (aka gas and bloating).

So clearly the goal is to enable your small intestine to do its job if you fall into one of these three categories of lactose intolerant. Avoiding dairy or taking a pill that has lactase with your meals are two obvious ways to prevent GI symptoms. If you're not completely intolerant of lactose, you can often manage your symptoms without completely excluding dairy. Simple choices like limiting milk to small amounts, eating hard rather than soft cheeses, and using lactase-treated products are all good options. If you want to get scientific about it, people with lactose malabsorption can generally tolerate less than 6 grams of lactose without symptoms. Here's my favorite chart detailing the lactose quantity in common dairy items, but there are plenty others out there to choose from.

Being mindful of what you eat and learning what works for you are important. Keep in mind that it may take as long as 10 hours for the dairy you eat to reach your colon. Another common misconception is that not drinking milk will lead to not getting enough calcium, but research shows this to not be the case as long as you have a healthy, well balanced diet. If you're concerned you don't get enough calcium in your diet, talk to your doctor about calcium/vitamin D supplements.

The bottom line? While you may be in the lucky minority, the majority of adults have some form of lactose intolerance, but that doesn't mean you need to avoid dairy altogether. Making smart dietary choices and being mindful of your gut's reaction to what you eat are all important ways to learn to love your gut!

-The Gut Doc


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