Lactose Intolerance: Common Misunderstandings

Abstract

Lactose intolerance primarily refers to a syndrome having different symptoms upon the consumption of foods containing lactose. It is one of the most common form of food intolerance and occurs when lactase activity is reduced in the brush border of the small bowel mucosa. Individuals may be lactose intolerant to varying degrees, depending on the severity of these symptoms. When lactose is not digested, it can be fermented by gut microbiota leading to symptoms of lactose intolerance that include abdominal pain, bloating, flatulence, and diarrhea with a considerable intraindividual and interindividual variability in the severity of clinical manifestations. These gastrointestinal symptoms could be similar to cow’s milk allergy and could be wrongly labeled as symptoms of “milk allergy.” There are important differences between lactose intolerance and cow’s milk allergy; therefore, a better knowledge of these differences could limit misunderstandings in the diagnostic approach and in the management of these conditions.

Congruency of Genetic Predisposition to Lactase Persistence and Lactose Breath Test

“…Lactase deficiency, however, may be secondary to acquired conditions including: severe malnutrition, mucosal damage due to celiac disease and inflammatory bowel diseases (IBD), bacterial or viral enteritis (e.g., rotavirus), and parasitic disease (e.g., giardiasis, cryptosporidiosis), actinic enteritis, drugs (kanamycin, neomycin, polymycin, tetracycline, colchicine, and other chemotherapeutic drugs), gastrointestinal surgery, short bowel syndrome, and small bowel bacterial overgrowth (SIBO). All these conditions may lead to either a reduction of absorptive capacity or down-regulation of lactase expression in the small intestine [7,8,9,10].…”

Intolerância a lactose

“…Lactose é um açúcar presente em grande quantidade no leite, quando quebrada por uma enzima a lactose gera a galactose e glicose. Em algumas pessoas há uma deficiência na produção da lactase, enzima que degrada a lactose 2,3 .…”

“…A deficiência em lactase congênita é uma desordem rara que possui apresentação clinica severa, principalmente em neonatos. Essa condição é resultado de mutações no gene da Lactase-Florizina Hidrolase o que causa deficiência na atividade da lactase no intestino 3 .…”

Development and validation of the paediatric Carbohydrate Perception Questionnaire (pCPQ), an instrument for the assessment of carbohydrate‐induced gastrointestinal symptoms in the paediatric population

“…1 Although carbohydrate malabsorption and intolerance are not equivalent, 1,6 the terms 'carbohydrate malabsorption' and 'carbohydrate intolerance' are often confused or used interchangeably. 7 This has led to conflicting results of therapeutic studies of carbohydrate restriction diets. 8 Since it is intolerance that is of clinical relevance rather than malabsorption, the treatment of carbohydrate-related symptoms, for example, by diet or enzyme replacement, should not be primarily aimed at altering malabsorption but rather at improving abdominal symptoms.…”

“…Intolerance after a carbohydrate challenge rather than malabsorption corresponds to a history of clinical symptoms 1 . Although carbohydrate malabsorption and intolerance are not equivalent, 1,6 the terms ‘carbohydrate malabsorption’ and ‘carbohydrate intolerance’ are often confused or used interchangeably 7 . This has led to conflicting results of therapeutic studies of carbohydrate restriction diets 8 .…”