What Is Lactose Intolerance?

(Last Updated On: December 1, 2020)

So either you have a bad time when you cross paths with dairy, or one of your friends has a bad time when they come across milk and its kind. However you’re related to it, you’re probably aware of lactose intolerance and the following trip to the bathroom you need after having lactase without some pills. So what’s up with lactose intolerance? 

Types of Lactose Intolerance

Lactose intolerance comes in primary and secondary forms. Primary intolerance is the most common type. It just means you develop it later in life. The vast majority of people start life lactose tolerant–which means they produce lactase. But over time as infants stop relying on milk as a sole means of nutrition, lactase production falls off into adulthood. 

Secondary lactose intolerance comes into play with conditions of the small intestine that invariably cause intolerance. There’s also just the rare congenital situation, where you’re just born lactose intolerant.

Beyond taking pills, there’s no real catchall “cure” for primary lactose intolerance. Though for the secondary sufferers, they can sometimes be treated if the condition causing it is treated. 

Who Gets Lactose Intolerant?

The thing about the condition is that a lot of people either are lactose intolerant, or will be later in their lives. Like we’re looking at lactose intolerance affecting around 75% of the world’s population

Typically the older you get, the more likely you are to develop lactose intolerance. Though that’s a little misleading–it’s really just that children are way less likely to be lactose intolerant. Because… You know, most babies drink milk. Sort of in tune with age, premature babies are more likely to be lactose intolerant–since the parts of the small intestine that deal with lactase develop later.

Though you can also develop lactose intolerance as a result of diseases that affect the small intestine

There’s also a lot of data that suggests a correlation between ethnicity and lactose intolerance rates–chiefly Northern Europeans are far less likely to be lactose intolerant. No like, Northern European countries have lactose intolerance rates hovering around 20%– a far cry from the generally agreed upon worldwide rates between 60% and 75%. 

Why Do Europeans Avoid Lactose Intolerance?

We know that you can inherit lactose intolerance from your parents. Some treatments also involve exposure to lactase–broadly just having some lactase to literally build up tolerance. So it stands that many associate the Northern European tolerance with dairy farming–as Northern European lactose tolerance lines up quite well with when they started farming dairy 8-9,000 years ago. 

In case you were wondering, the gene you inherit is the LCT gene, where mutations of it can cause congenital lactose intolerance. Its reduced expression in adulthood (developing lactose intolerance later in life) is also probably something you inherit. 

Though dairy farming was also around outside of Northern Europe, so it doesn’t stack up as well to just say “Northern Europeans just farmed” as it might seem. Plus, the spread of lactose tolerance within the Northern European population was a pretty massive actor. Almost too massive to just have been selection alone–which leaves some to point to migrations toward Northern Europe that eventually led to more pervasive lactose tolerance. 

Speaking of milk, see if you know who makes the most here.

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About Kyler 563 Articles
Kyler is a content writer at Sporcle living in Seattle, and has just finished his undergraduate at the University of Washington. He's been writing for Sporcle since 2019 and has accumulated so much random, general knowledge he'd rather not think about it. Most of his free time is spent drinking black coffee like water.