Learn from scratch: lactose intolerance is most often a threat to residents of Yakutia

Lactose intolerance is most often suffered by residents of Yakutia. This is the conclusion reached by scientists from the National Center for Genetic Research. This condition is also common in people living in Kabardino-Balkaria and Dagestan, and less often in residents of the Vladimir region. About which other regions of the population have problems with milk digestibility, how this condition manifests itself and how dangerous it is, see the Izvestia article.

Who has a predisposition to intolerance

In Russia, the predisposition to lactose intolerance (inability to digest milk sugar) is highest among residents of Yakutia, experts from the National Center for Genetic Research have found (the analysis is available to Izvestia). Scientists have studied mutations in the MCM6 gene (it is responsible for changing the activity of the lactase enzyme), examining samples from more than 40 thousand people from 67 regions of Russia.

"This gene contains regulatory regions of the LCT gene encoding lactase," said Irina Kolesnikova, a leading researcher and chairman of the expert council of the National Center for Genetic Research. — In newborns, the enzyme is secreted at a high level, but after the end of breastfeeding, its activity usually decreases, so adults may have problems with the absorption of lactose and unpleasant symptoms when drinking milk.

Photo: Global Look Press

Residents of Dagestan, Kabardino-Balkaria and North Ossetia are highly likely to not digest milk and products derived from it, the study notes.

The scientists concluded that the prevalence of mutations in the LCT gene in different regions of Russia varies depending on the national composition and is moderately correlated with the proportion of the East Slavic population in them.

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Thus, residents of the Vladimir, Arkhangelsk, Ryazan, Vologda and Kirov regions have good milk tolerance. For example, the national composition of Yakutia is characterized by a relatively small number of Russians (32.6%) and a predominance of the Yakut nationality (55.3%). In Dagestan, Kabardino-Balkaria and North Ossetia, the Russian population also accounts for a small proportion: 19.8% in Kabardino—Balkaria, 3.2% in Dagestan and 18.9% in North Ossetia.

Photo: Global Look Press/Peter Steffen

"The diversity of ethnic groups in Russia and the constant migration of the population make the genetic assessment of the Russian population and its individual parts in different regions very relevant," the authors note.

According to the results of the analysis, the prevalence of lactose intolerance in Russia is 61%. For comparison, in Ireland and Denmark, this figure is 4%, in China — 85%, in Vietnam — 98%, in Yemen — almost 100%.

The overall global prevalence of lactose intolerance is about 68%.

Causes of lactose intolerance

Mutations in the MCM6 gene really increase the risks of lactose intolerance, Alexander Reznik, a geneticist at the Hadassah Medical Moscow Clinic, told Izvestia. He noted that this intolerance is programmed at the genetic level and only about 7.5 thousand years ago, people from Northern Europe developed the ability to digest milk in adulthood.

— This event went hand in hand with the domestication of cattle and affects only a quarter of the world's population. There is often talk of a north-south divide regarding lactose intolerance. In the Scandinavian countries, almost 90% of the population can digest lactose, while in the southern regions of Europe only about 10-30%, and in Asia — about 0-2%, — said the geneticist.

Photo: IZVESTIA/Sergey Lantyukhov

The risk of lactose intolerance can be increased by age, intestinal diseases, previous infections (for example, rotavirus), chemotherapy and radiotherapy, the presence of inflammatory diseases or celiac disease (gluten intolerance), dysbiosis, Irina Kolesnikova noted.

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Diseases may not manifest themselves for years and destroy the body at the same time.

A key preventive measure for the condition is exclusion from the diet or restriction of the consumption of dairy products, said gastroenterologist Andrey Yakushev. Also, according to him, doctors prescribe enzyme preparations or prebiotics and probiotics to people with this syndrome.

"But more often, patients choose not to eat dairy products," he noted.

Photo: Global Look Press/Svetlana Balyn

Late diagnosis of the condition in adults, according to Irina Kolesnikova, can cause psychological discomfort, lead to impaired absorption of nutrients, deficiency of vitamins and minerals, such as calcium or vitamin D.

"Children with undiagnosed lactose deficiency may experience growth retardation, body weight deficiency, and other developmental problems due to impaired nutrient absorption," she added.

For timely diagnosis of the condition in infants, it is important to monitor whether he regurgitates after feeding, in older children and adults — the reaction of the stomach to the intake of dairy products, the expert noted. According to her, the characteristic signs are bloating, flatulence, diarrhea, nausea and vomiting.

If poor digestion of dairy products is suspected, genetic testing, a breath test, and a lactose tolerance test are now available, Irina Kolesnikova concluded.