Disaccharidase deficiency enteropathies: causes

Causes and pathogenesis of disaccharide-deficient enteropathies

In the intestinal mucosa, the following enzymes are produced: disaccharidases:

• isomaltase cleaves isomaltose;
• thermostable maltase II and III - splits maltose;
• invertase - cleaves sucrose;
• trehalase - cleaves trehalose;
• lactase - splits lactose.

These enzymes split disaccharides into monosaccharides (in particular, invertase splits sucrose into fructose and glucose, maltase - maltose into two glucose molecules, lactose - lactose to glucose and galactose).

The most common deficiency is lactase, which causes milk intolerance (it contains lactose), invertases (intolerance to sugar), trehalase (intolerance to fungi).

In connection with the deficiency of disaccharidases disaccharides do not split and under the influence of bacteria break down in the intestine; at the same time carbon dioxide, hydrogen, organic acids are formed. These substances irritate the mucous membrane of the small intestine, cause the development of fermental dyspepsia.

Deficiency of disaccharidases can be primary, congenital (inherited by autosomal recessive type) and secondary (due to various diseases of the gastrointestinal tract and taking certain medications - neomycin, progesterone, etc.). Such diseases as chronic enteritis, ulcerative colitis, Crohn's disease can cause the development of secondary disaccharidase insufficiency. Especially often there is a deficiency of lactase, in addition, the activity of this enzyme decreases with age, even in healthy people.

By splitting disaccharides into monosaccharides (lactase for glucose and galactose, sucrose for glucose and fructose, maltose for two glucose molecules, etc.), disaccharidases create conditions for their absorption. Violation of the production of these enzymes leads to intolerance of disaccharides, which is described for the first time 30 years ago. Thus, lactase insufficiency was ascertained by A. Holzel et al. In 1959, the insufficiency of sugar - NA Weijers et al. In 1960. Publications of recent years indicate a fairly high prevalence of disaccharidase deficiency, and often there is a lack of simultaneous several enzymes that break down the disaccharides. The most common deficiency is lactase (milk intolerance), invertase (intolerance to sucrose), trehalase (intolerance to fungi), cellobiasis (intolerance of foods containing high amounts of fiber). As a result of the lack or inadequate production of disaccharidases, uncleaved disaccharides are not absorbed and serve as a substrate for active bacterial multiplication in the small and large intestine. Under the influence of bacteria, disaccharides decompose to form tricarbon compounds, CO2, hydrogen, organic acids, which irritate the intestinal mucosa, causing a symptomatic complex of fermentative dyspepsia.

A particularly common cause of disaccharidic insufficiency is the deficiency of lactase in the small intestinal mucosa, occurring in 15-20% of adults in Northern and Central Europe and the white population of the USA and 75-100% in the indigenous populations of Africa, America, East and South-East Asia. The results of studies conducted on American blacks, inhabitants of Asia, India, some regions of Africa and other population groups, showed that a fairly large proportion of the indigenous population of a number of countries and continents feel almost healthy. In Finland, lactase deficiency occurs in 17% of the adult population. Russians have a lactase deficiency more often (16.3%) than Finns, Karelians, Vepsians living in the Karelian ASSR (11.0%), and Mordvinians (11.5%). According to the authors, the same frequency of hypolactasia in Finns, Karelians and Mordovians is due to the fact that in ancient times these nationalities were one people and at the same time there arose dairy cattle breeding. The authors emphasize that these data confirm the correctness of the cultural and historical hypothesis, according to which the degree of repression of the lactase gene can serve as a kind of genetic marker.

The results of research by some researchers have led to the conclusion that under certain environmental conditions, the nature of nutrition over a long historical period can lead a person to significant genetic changes. In some situations in the course of evolution, the nature of nutrition can affect the ratio of individuals in populations with different gene pools, causing an increase in the number of people with the most favorable set of genes.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]