Lactose Intolerance—Old and New Knowledge on Pathophysiological Mechanisms, Diagnosis, and Treatment

Lactose intolerance is a pathology frequently encountered today. It occurs when the activity of lactase in the intestine is reduced or absent, with consequent failure to digest lactose. The global prevalence of this clinical condition is estimated of about 57% with instrumental methods, while the real prevalence exceeds 65%. The absence of lactase determines both the excessive osmotic load in the small intestine and the fermentation of lactose by the bacterial flora with consequent production of short-chain fatty acids and gas. This latter process is responsible for the onset of symptoms associated with lactose intolerance (abdominal pain, bloating, flatulence, etc.) which arise after the intake of lactose. Several studies have shown an increased risk of developing various pathologies for lactose-intolerant subjects (some types of cancer, osteoporosis, etc.). Therefore, it is essential to diagnose and properly treat this pathology. Various options exist for diagnosing lactose intolerance: Hydrogen Breath Test, genetic test, Quick Lactose Intolerant Test, Lactose Tolerance Test, Gaxilose Test. Like diagnostic methods, there are several options for treating intolerance. In addition to a food restriction, the use of exogenous enzymes and/or probiotic and the selection of milk containing specific types of beta-caseins less correlated to the appearance of gastrointestinal symptoms are very useful. The aim of this review is to illustrate the main and most modern diagnostic and therapeutic choices for lactose intolerance currently available.