Letzte Aktualisierung am 6. September 2024 von Dr. Michael Zechmann-Khreis
Stone Age people with lactose intolerance
Around 7,500 years ago, northern European humans developed the ability to digest milk, or lactose, even in adulthood. This adaptation took place around the same time as the start of livestock farming and agriculture. In northern Europe, people who could digest lactose obviously had survival advantages. As a result, this genetic variation spread more and more. This also means that lactose intolerance is not a disease, but actually a normal human variation that has become increasingly rare in Europe. The global distribution of lactose intolerance is an exciting topic, with still little data.
Ethnic view of primary lactose intolerance
The production of the enzyme lactase is genetically controlled. In the course of their evolution, northern European humans have acquired the ability to continue producing the enzyme lactase in adulthood.
This development went hand in hand with the domestication of cattle and affects only 1/4 (other sources 1/3) of the world’s population.
There is often talk of a north-south divide with regard to lactose intolerance.
In Nordic countries, almost 90% of the population can digest lactose, whereas in southern regions of Europe only about 10-30% and near the equator and in Asia only about 0-2% can digest lactose. The figures on this vary widely and are sometimes very imprecise.
Lactose intolerance in men and women
Some studies have looked for a difference between the sexes. However, no clear evidence has ever been found, i.e. lactose intolerance occurs equally frequently in men and women.
Scarce data
Many people who actually come from lactose-intolerant peoples but grow up in milk-drinking cultures no longer show lactose intolerance symptoms or claim to have no symptoms. This is an indication that lactose intolerance is often culturally determined. Presumably, the mixing of primary and secondary forms (loss of lactase production due to a lactose-free diet) is often found here. According to some authors, the African tribes Tuareg and Maasai, as well as a tribe in the south of Sudan, are also out of line, as they actually live in southern regions but consume milk. Only about 20-40% of them are lactose intolerant. This is due to the fact that they practise intensive livestock farming and therefore consume fresh and fermented dairy products relatively frequently. Other studies say something different. For example, around 60% of the Masai are already lactose intolerant as children.
In South America, 50% of the population is lactose intolerant; in North America (USA), a study has shown that 15% of white Americans, 53% of Mexican-Americans and 80% of African-Americans are lactose intolerant. Other studies say that around 80% of Mexicans are lactose intolerant.
In Thailand, the values of alleged lactose intolerants in various studies range from 50% to 100%, with a tendency towards 80%.
The data on the global distribution of lactose intolerance is therefore not clear, but it is certain that Asians and Africans – and the cultures descended from them – have little lactase activity, and all Northern Europeans – and cultures descended from them – still produce lactase (to varying degrees) even in old age.
We have collected some data on this in recent years and created the following map. It shows the worldwide distribution of lactose intolerance in the recent – i.e. currently living – population. This means that an average of the total population of all ethnic groups is shown. This is clearly visible in South Africa. The black population is said to be about 90% lactose intolerant, European immigrants and some other immigrant groups about 10% lactose intolerant. Converted to the recent total population (corresponding to the composition of the population according to the CIA World Factbook), this results in an average of around 76% lactose intolerance.
However, the map only shows the distribution schematically! As I said, the data situation is sometimes very weak and we had to extrapolate values from time to time. For example, there is no data available for Madagascar (22 million people). Due to the highly mixed population (Arabs, Creoles, Europeans, Asians, … ), there could well be less lactose intolerance (%-100%).
Sources
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