Carbohydrate-related nutritional and genetic risks of obesity for indigenous northerners

Abstract

By the end of the 2010-s the prevalence of obesity among the indigenous people of the North approached to the all-Russia one and the speed of the spread of other metabolic disorders exceeded the average all-country levels. Aim of this review is to analyze data on the increase in consumption and variety of sugars coupled with a genetic specificity of regulation of saccharidase activity and their possible impact on the matters. Results. It have been shown that the traditional protein-lipid-based northern type diet has substantially changed and now contains a high proportion of carbohydrates. The carbohydrate per capita consumption among the indigenous people of the North has reached the all-Russia average level (40 kg per year) which exceeds the European average of 36.2 kg per year. The variety of food disaccharides has also considerably increased. The daily consumption of sucrose, at the beginning of the 20th century it was the only sugar contained in the store-bought foods, increased from 30 g in the 1930s to 63-65 g in the 1990s. In addition, the proportion of sucrose dropped to 60-70 per cent, while the contribution of other disaccharides (lactose, trehalose) reached 30-40 per cent. Daily starch consumption has also increased and got close to the national average (males 228.5 g, females 157.5 g per day). Such a diet in itself increases the risk of metabolic disorders and obesity. The high prevalence of the genotypes that determine reduced levels or inability to produce sucrase-isomaltase, lactase, trehalase, salivary and pancreatic amylases among northerners becomes a negative cofactor. The evolutionary driven and embodied in genotype reduced ability of the indigenous Arctic people to digest complex carbohydrates is in a conflict with the growing consumption of sugars and starchy foods in modern conditions. The northern people have a high proportion of carriers of the AG deletion in SI gene (3.5-14.3% against 0.05-0.2% among Europeans) which determines malabsorption of sucrose. The CC/LCT genotype (96.6% in northerners, 36-49% in Russians) presumes lactose intolerance and is associated with the risk of childhood obesity. The occurrence of A allele in the rs2276064 locus of TREH gene (trehalose intolerance; 31.3-58.9% in northerners, 1.9% in Europeans) increases the probability of the onset of type 2 diabetes mellitus. According to preliminary estimates, 28-52% of the northerners completely lost AMY gene that precludes or drastically reduces the ability to digest starch. A reduction in the number of copies of AMY gene (the average number of copies AMY2A - 4, in, in northerners it is 1.0-1.4) is associated with overweight and obesity. Conclusion. The analysis shows that, in the case of the modern indigenous northerners, nutritional and genetic risks of metabolic disorders accumulate.