About 75 % of the world’s population is lactose intolerant. Let’s not kid ourselves: Lactose intolerance is very common, in fact, it’s the norm. Now you’re probably asking yourself why you have to explain to others – again and again – why you’re avoiding this particular milkshake or other dairy product. It’s because lactose intolerance does not affect the majority of Central Europeans. To understand this, one has to go back far in history.
1. Once upon a time….
… humans produced the enzyme “lactase” only during infancy so that they could subsist on mother’s milk. Mother Nature envisioned that in adulthood, the production of lactase decreases bit by bit. About 7500 year ago, mankind discovered that the milk of cows and goats not only tastes good but also significantly increases their chances of survival. Thus, over time, a genetic mutation, the so-called “lactase persistence” gave us the ability to break down lactose even as adults.
2. The North-South divide: The influence of sunlight
If you study the graph showing the global prevalence of lactose intolerance, something immediately becomes clear: There are far fewer lactose intolerance people in the North than in the South. The main reason for this is the fact that there is much less sunlight in the North. Sunlight, however, promotes the production of Vitamin D which is, in turn, essential for calcium absorption. Lactose can compensate for this deficiency. It allows the body’s calcium stores to be maintained even in the fall and winter. Thus, in northern latitudes, close to 90 % of the locals can digest lactose. In southern regions, on the other hand, only about 10 to 20 % of the population tolerates lactose; in close proximity to the equator that number diminishes to just 2 %.
3. Lactose intolerance in Germany
In Germany, about 15 to 20 % of the population is lactose intolerant, in other words, about every fifth German. For us, milk and dairy products are a staple of our diets. In Asia, on the other hand, dairy products are not regularly consumed and thus lactose intolerance is not considered much of an issue.