Introduction 

A disaccharide is a type of carbohydrate that is formed when two monosaccharides condense, losing a molecule of water in the process. Some of the most well-known disaccharides are sucrose (table sugar) and lactose (milk sugar), which is composed of glucose and galactose. Lactose, the disaccharide present in milk, is made up of two monosaccharides: glucose and galactose.

Lactose = Glucose + Galactose.

Lactose Metabolism

Enzymatic hydrolysis is the digestive process that breaks down macromolecules like lactose. This process requires the addition of water and the action of specific enzymes. Lactase, which is primarily found in the cells of the small intestine of newborns and some adults, is the enzyme responsible for breaking down lactose. Its absence leads to symptoms of lactose intolerance in those who consume dairy products.

After the nursing period, lactase levels decrease in most mammals, including humans. This enzymatic reduction hinders the proper digestion of lactose, causing discomfort in adults who consume milk.

Persistence of Lactase in Adulthood

Despite the widespread decrease of lactase, some individuals maintain the active enzyme throughout their lives. This phenomenon is due to genetic mutations that allow the persistence of lactase, thus enabling the consumption of milk without negative effects.

The development of lactase persistence is linked to evolutionary history, particularly to the agricultural revolution, pasturing, and the consumption of dairy products. In regions like Northern Europe, persistent lactase provided an evolutionary advantage, as lactose helped in the absorption of calcium, crucial for bone health in areas of low solar radiation.

Genetic Variants Associated with Lactase Persistence

Genetic polymorphisms (SNPs) have been identified that determine the phenotype of Lactase Persistence (LP) or Lactase Non-Persistence (LNP). These SNPs are located in the MCM6 gene, which regulates the expression of the lactase gene (LCT). The polymorphism C/T_13910 (rs4988235) is the main responsible factor for lactase persistence in Europe and some African populations.

Clinical Implications

The CC genotype in the C/T_13910 SNP indicates a high genetic predisposition to lactose intolerance, while the C/T or T/T genotypes indicate lactase persistence and therefore a lower predisposition to this intolerance. Knowing this information allows for the personalization of dietary guidelines and treatments in professional consultation.

With tools like N·GENE, it is possible to discover genetic predispositions and personalize dietary advice more precisely. Take your practice to another level and improve the patient experience with an approach that considers genetics.