Lactose Intolerance

Lactose intolerance is a reaction in your digestive system to lactose, the sugar in milk. It causes uncomfortable symptoms after you eat dairy products. Many people have difficulty digesting lactose, but not everyone experiences noticeable symptoms from it. If you do, it’s called lactose intolerance.

What is lactose malabsorption?

Lactose malabsorption is the inability to break down and absorb lactose molecules in your digestive system. It’s common — in fact, about 65% of adults worldwide can’t break down and absorb lactose. Unabsorbed lactose passes undigested through your gastrointestinal tract, causing symptoms for some people.

What’s the difference between lactose malabsorption vs. lactose intolerance?

Everyone with lactose intolerance has lactose malabsorption, but not everyone with lactose malabsorption has lactose intolerance. One way of thinking about it is that malabsorption happens in your small intestine, while symptoms of food intolerance happen later in your large intestine.

Your small intestine is where most of the nutrients from your food are absorbed. Your small intestine breaks nutrients down into smaller molecules that can pass through the intestinal wall into your bloodstream. Everything that isn’t absorbed in your small intestine passes to your large intestine.

Undigested sugar molecules in your large intestine produce more water and more gas. They trigger your large intestine (colon) to secrete extra fluid to help pass them through. They produce gas when the bacteria in your colon ferment them. This can lead to digestive symptoms such as diarrhea and gas pain.

How noticeable your symptoms are will depend on other variables. Can you break down lactose a little bit, or not at all? How much lactose do you eat at a time? What other conditions might affect the water and gas content in your colon? These are some of the factors your healthcare provider will explore.