Lactose intolerance: misbelief and reality

Abstract

Introduction. Nowadays a common misrepresentation of lactose intolerance, perpetuated by advertising of lactose-free diets, low-lactose products, the increased popularity of veganism has led to the exclusion of lactose containing foods.Aim of the study. The aim of this review was to evaluate the current information regarding lactose intolerance in order to establish whether the prevalent misconception has scientific grounds. Materials and methods. An extensive English search was undertaken of the PubMed database for the terms “lactose intolerance”, “self-reported lactose intolerance”, and relevant articles from 2010-2020 were examined. Results. Lactose intolerance is associated with gastrointestinal symptoms with intra- and interindividual variability after ingestion of lactose-containing foods, this relation being influenced by: the expression of lactase, dose of lactose, intestinal flora, gut transit time, ingestion of other dietary components, the sensitivity of the gastrointestinal tract and the genetically programmed decrease in lactase synthesis. While lactose is the main factor considered, other maldigested carbohydrates, dairy related nutrients (some fats or casein proteins) and some gastrointestinal diseases may be taken in account. A nocebo effect has also been considered to contribute to the exaggerated understanding of lactose intolerance, individuals erroneously attributing their symptoms to lactose consumption. Inappropriate avoidance of dairy products can lead to nutritional inadequacy, increasing the risk of osteoporosis, bone fractures, hypertension. Conclusions. The common wrong understanding of lactose intolerance has led to the increasing misleading self-diagnosis, a decision that results in a series of consequences associated with diet restrictions.