What does and how does lactase work?

And why your gut doesn't get happy when it's missing

If you have lactose intolerance (or suspect it), you quickly come across the word lactase. But what exactly is it, what does it do in your gut, and why do you get symptoms when it's in short supply? Here you'll read it explained clearly and practically, so you can better understand what's going on in your gut.

What is lactase?

Lactase is an enzyme produced in the lining of your small intestine. Think of it as scissors specially designed to cut lactose.

Lactose is the milk sugar found in milk and dairy products. This sugar consists of two sugar molecules stuck together: glucose and galactose. As long as they are stuck together, your body cannot absorb them. They are too big to pass through the intestinal wall.

That's where lactase comes in: it neatly cuts lactose in half. Only then can glucose and galactose pass separately through the intestinal wall and be absorbed into your blood, where they serve as a source of energy.

Lactose as a big Lego brick

Imagine that lactose is a large Lego brick made up of two smaller bricks. As long as they are firmly stuck together, the block won't fit through the small opening of your intestinal wall. But if you unclick the bricks, they can go in (neatly one at a time).

Lactase is then like the handy little hand that takes apart the Lego bricks. No lactase? Then the block simply remains too big to continue.

What happens when you have too little lactase?

If your body does not produce enough lactase, the lactose remains in its entirety in your small intestine. And because it can't be absorbed, it naturally slides on to the colon. There, your gut bacteria are already waiting to party.

These bacteria enthusiastically begin to ferment, a kind of digestive process that converts lactose into gases and acids. Might sound cozy, but in your tummy it feels just a little less pleasant.

Read more about: What is lactose intolerance

The most common complaints

Make your insufficient lactase to, then lactose remains undigested in the small intestine and advances to the colon. There go intestinal bacteria with it. It's called fermentation: there arise gases and acids which can irritate the intestinal wall. You notice the consequence as flatulence, bloating, cramps and sometimes diarrhea. How much trouble you are in depends on your lactase threshold and of the portion of lactose that you take in.

• Flatulence: you have to let off gas more often, often with sound AND smell. Not useful during a meeting or on the train.
• Abdominal pain: your intestines react to the pressure created by gas. This can feel nagging, stinging or cramping.
• Cramps: especially in the lower abdomen, and sometimes so intense that you have to sit down for a while.
• Bloating: Your belly swells as if you are suddenly five pounds heavier. Your pants are tighter and you feel bulky.
• Sometimes diarrhea: acids attract water in your intestines, which can lead to watery, sudden stools.

When do you get complaints?

Many people notice within 30 to 120 minutes after a lactose-containing meal the first signs. This varies from person to person and from situation to situation. A splash of milk in coffee can set one person off, while another can tolerate a small bowl of yogurt just fine. It is always about the balance of ingested lactose and the lactase that your body can provide at that time.

In plain language

Lactase is the clipping scissors. With enough lactase cuts your lactose into two bite-sized pieces and your tummy stays calm. Without enough lactase passes lactose through to your colon, where bacteria build a fermentation party. You can feel that as gas, cramps and bloating. By your servings directing, choosing lactose-free options or lactase in when it is convenient, you keep a grip on your symptoms.

Want to know more?

Want to better understand why cow's milk sometimes causes so many symptoms? Then also read our blog: Why your tummy might say 'no' to cow's milk