We often hear about lactose intolerance or lactose-free products, but what does it mean?
First, it is necessary to understand what lactose is.
Lactose is the sugar naturally present in milk of animal origin and, therefore, also in its derivatives; in order to be absorbed by our body, it is necessary that an enzyme, present in the intestine, called lactase capable of breaking down this sugar into its two main components: glucose and galactose, intervenes.
This enzyme appears as early as during pregnancy and reaches its maximum level at birth and during lactation, so that the infant can properly absorb breast milk. Later, with growth there is a progressive decrease, the rate of which varies from individual to individual.


Lactose intolerance is the inability of our bodies to break down lactose into its main components. This causes fermentation by intestinal bacteria, leading to bloating, flatulence and diarrhea. In this case, there is no reaction from the immune system, so this is why we speak of intolerance and not allergy, as is the case with milk proteins.
Lactose intolerance can arise mainly due to three causes:

  • By a lack from birth of the enzyme lactase. In this case, the body is unable to produce it and intolerance occurs from the first intake of breast milk.
  • For a progressive reduction of the enzyme during growth until it disappears completely. This is the most common cause.
  • Finally, an intolerance secondary to acute (bacterial or viral intestinal infections) or chronic disease (celiac disease, Crohn’s disease, irritable bowel…).


The typical symptoms of sufferers occur 30 minutes to 2 hours after ingestion of products containing lactose, which is meanwhile fermented by the intestinal flora and transformed into hydrogen and organic acids. These compounds cause abdominal bloating and pain (cramp-like), fatigue, nausea, meteorism, flatulence, and diarrhea. The extent of symptoms varies from patient to patient, depending on tolerance and degree of lactase production.


One of the most widely used methods to diagnose lactose intolerance is the H2-Breath Test. This test evaluates the presence of hydrogen in the patient’s breath in at least 6 air samples obtained over a 3-hour period. The test is positive if an excessive amount of hydrogen is present, as this fermentation product is absorbed from the circulation and eliminated through the breath.
There are, in addition, genetic tests used primarily to diagnose early lactose intolerance.


The only possible therapy is the total exclusion of lactose-containing foods from the diet. In fact, if it is secondary intolerance (i.e., due to progressive deficiency or pathology), it is not necessary to eliminate it altogether but to find one’s tolerance threshold. On the other hand, for those with a primary intolerance (the enzyme is not produced), lactose must be totally eliminated.
Unfortunately, totally eliminating or reducing lactose is not that simple because it is often used as a preservative or thickener, so it is necessary to learn to read food labels carefully. In addition, it is often used as an excipient in various drugs or supplements.
On the other hand, however, there are delactose products on the market such as milk, some fresh cheeses, and lactose-free products. In addition, it should be remembered that not all cheeses need to be eliminated from the diet since those that are more mature are low or even lactose-free and, therefore, can be safely consumed even by those suffering from this disorder.

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