What does and how does lactase work?

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

If you have (or think you have) lactose intolerance, you've probably seen the word lactase come up before. But what exactly is it, and why is it so important in your digestive system? In this blog, we explain. So you can better understand what goes on in your tummy.

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

In people with lactose intolerance, this fermentation feast leads to symptoms such as:

• 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?

Most people experience symptoms between 30 minutes and 2 hours after eating or drinking something with lactose. But it depends a lot on:

• how much lactose you ingest
• how much lactase your body still makes
• how sensitive your digestion is at that moment

Some people get symptoms from just a splash of milk in their coffee, while others can tolerate a slice of cheese or a yogurt. So it's all about the balance between what you eat and what your body can handle.

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