Lactase Deficiency and Lactose Intolerance: Current Understanding and Future Directions

Introduction and purpose: Lactose, the primary carbohydrate in milk, requires the enzyme lactase for digestion. Deficiency in lactase activity leads to lactose intolerance, causing gastrointestinal symptoms. Understanding the genetic and environmental factors influencing lactase expression and activity is crucial. Moreover, accurate diagnostic methods and effective treatments are needed to manage lactose intolerance. This review aims to explore the current knowledge on lactase deficiency, lactose intolerance, diagnostic methods, and treatment options. State of knowledge:  Lactase deficiency encompasses congenital, primary, and secondary forms, each with distinct etiologies. Although often used interchangeably, lactase deficiency and lactose intolerance differ. However, the association between lactase deficiency and lactose intolerance is complex, influenced by various factors including dietary habits, gut microbiota, and gastrointestinal motility. Diagnostic methods are limited, and treatment strategies primarily involve dietary modifications, lactase supplementation, and probiotics.  Conclusion: Lactose intolerance presents significant clinical challenges, often underrecognized and misdiagnosed. Despite diagnostic advancements further research is needed to refine diagnostic accuracy. Treatment focuses on dietary adjustments, enzyme supplementation, and probiotics. Balancing symptom relief with nutritional adequacy is essential. Future studies should explore the role of gut microbiome modulation in lactose intolerance management through clinical trials.