Carbohydrate malabsorption. Interpretation of the breath test.

Carbohydrate malabsorption, especially of lactose and fructose, is a common condition in clinical practice. Accurate diagnosis is essential to avoid unnecessary dietary restrictions that could compromise bone and cardiovascular health. The breath test with hydrogen (H₂) and methane (CH₄) determination is becoming the preferred technique due to its non-invasive nature and high sensitivity. In this review, we will focus on lactose and fructose malabsorption, as these are the most frequent types.