Can all adults tolerate milk?
Most people can't stand milk
Babies naturally tolerate the components of breast milk, but if the suckling stops, the majority of the world population can no longer tolerate milk.
The problem is the lactose content in milk, a small, energy-rich sugar molecule. The intestines do not absorb the lactose. In order to extract the energy, lactose to glucose, among other things, must be broken down by the enzyme lactase.
If that does not happen, lactose will disrupt the intestines, resulting in diarrhea and ultimately malnutrition.
Northern Europeans in particular tolerate milk
Almost all people have the gene that forms lactase, but normally the gene becomes inactive when a baby no longer drinks breast milk. However, in a third of the world's population, especially from Northern Europe, the lactase gene remains active for a lifetime, thanks to a genetic mutation.
One in three adults drinks milk
The gene through which babies can tolerate milk usually becomes inactive after lactation. However, in approximately one third of the world's population, the gene is not switched off.