[Malnutrition in Inflammatory Bowel Disease].

Inflammatory bowel diseases (IBD), like ulcerative colitis (UC) and Crohn's disease (CD), are a group of conditions with unknown etiology. Their pathogenesis is based on the interaction between environmental, genetic, and immunological factors, as well as alterations in the gut microbiota. Although malnutrition can occur in any type of IBD, its prevalence, which fluctuates among 13.3 and 99.9%, it could be greater in CD due to more extensive involvement of the gastrointestinal tract; it may worsen depending on the activity, duration, and extent of the inflammatory response. The causes associated with malnutrition are mainly related to inadequate intake or absorption of nutrients, as well as a possible increase in energy metabolism triggered by an inflammatory response. Malnutrition has a significant clinical impact in IBD, as it has been associated with an increased risk of hospital admission secondary to infections, venous thromboembolism, non-elective surgery, prolonged hospital stays, and higher mortality rates. Due to its influence, it is mandatory to have validated diagnostic instruments to evaluate in the spectrum of the IBD, from the screening to diagnostic methods, whether to define it in remission to mild activity, and in severe or exacerbation periods.