Lactose intolerance in infants

Lactose intolerance in infants: What it really means

The diagnosis "lactose intolerance" is heard by parents very often, especially when it comes to colic, bloating or gas in the baby. However, it is important to understand that true, congenital lactose intolerance is an extremely rare genetic disorder. In the overwhelming majority of cases in infants, we are dealing with temporary, functional lactase deficiency, which is a normal stage of digestive system development.

What are lactose and lactase?

Lactose is the main carbohydrate, or "milk sugar", found in breast milk and infant formulas. It is a key source of energy for the infant. For the body to absorb lactose, it must be broken down into two simpler sugars — glucose and galactose. This process is carried out by a specific enzyme — lactase, which is produced in the small intestine.

Lactase deficiency is a condition in which the body produces insufficient lactase enzyme. As a result, undigested lactose reaches the large intestine, where it becomes "food" for bacteria. This fermentation process leads to the production of large amounts of gas (hydrogen) and water, causing the characteristic symptoms.

Temporary lactase deficiency: Why it is normal?

The infant's digestive system is immature, and its enzymatic activity is still being established. Often a situation occurs where the amount of lactose ingested (especially from so‑called "foremilk") is greater than the amount that the existing lactase can digest. This does not mean the enzyme is absent, it is simply temporarily insufficient. This is a physiological condition that usually resolves on its own by 3–4 months, when the intestine matures.

Symptoms of temporary lactase deficiency:

• Foamy, watery, often greenish stool with a sour smell.
• Severe abdominal bloating, rumbling.
• Distress and crying during or immediately after feeding.
• Frequent diarrhea.

It is important not to confuse this condition with true cow's milk protein allergy, which is an immune reaction and has other manifestations such as rash or blood streaks in the stool.