The lactose intolerance occurs because our body stops producing an intestinal lactase enzyme, responsible for “split” lactose into glucose and galactose (easily absorbed). By remaining intact in the intestine, lactose has two effects: on the one hand, the intestinal bacteria ferment it, and this causes flatulence and bloating, and on the other hand, lactose increases intestinal osmolality and attracts water to the lumen producing diarrhea and pain.
Babies are not lactase deficient at birth, so they tolerate breast milk very well. However, by around four years of age, 30-70% of children will no longer secrete the enzyme lactase in sufficient quantities and will suffer from varying degrees of lactose intolerance.
And then why can the rest of the population tolerate lactose? This is because about 7,500 years ago, a genetic mutation allowed to continue synthesizing the lactase enzyme and taking advantage of milk from other mammals to survive, giving an evolutionary advantage among the strongest ever views of adaptation to the environment. Lactase deficiency varies from person to person. Therefore, some people can tolerate yogurt, cheese, or small amounts of milk. In contrast, others cannot handle only small amounts or need to take lactase pills to facilitate dairy products’ digestion.
Three levels have been established, depending on the modest daily amount (in grams) of lactose: low (9 to 12 grams), medium (5 to 8 grams), and high (up to 4 grams). That is, a person with a level of mild intolerance digests lactose better than another with a high degree and, consequently, may consume dairy to a greater or lesser extent, according to the lactose content per 100 g of product.
In general, the population tends to tolerate a couple of dairy products a day, such as a couple of yogurts, since their lactose content is lower because lactic bacteria convert a large part of the lactose into lactic acid. It is important to emphasize that the consumption of low-fat dairy products, such as milk or yogurt or fresh cheese, should be prioritized over those rich in fat such as aged cheeses, cream, or butter since they have a considerable amount of saturated fat and also avoid those that have a content of more than 5-10% sugar.
Dairy products are a source of quality protein, vitamin B12, and calcium, among other nutrients, so an unjustified elimination of them is not recommended. It is advisable to read the labeling of prepared or precooked foods because they may contain lactose, powdered milk, milk, whey, and cream in their composition.