digestible

Digestible is an adjective used to describe the extent to which a substance can be broken down by the digestive system and absorbed as nutrients. In nutrition, digestibility refers to the proportion of a nutrient that is absorbed from the diet, as opposed to being excreted. Digestibility can be influenced by food matrix, processing, and health status.

Digestibility is often quantified as apparent digestibility, the ratio of nutrients recovered in feces to intake, or true digestibility, which accounts for endogenous losses. In animal studies, ileal digestibility (measured at the end of the small intestine) is also used, while fecal digestibility is common in humans.

Many factors affect digestibility. Cooking and mechanical processing can increase starch and protein digestibility; fiber, antinutritional compounds, fat content, and processing-induced changes can decrease it. The gut microbiota and overall digestive health also play significant roles.

Common examples: digestible carbohydrates include sugars and most cooked starches; indigestible carbohydrates are dietary fibers that reach the colon. For proteins, digestibility relates to amino acid availability; animal-based proteins generally have higher digestibility than some plant proteins, though processing and combination can improve plant protein digestibility.

In nutrition practice, digestibility informs energy estimates, protein quality, and diet planning for illness or malabsorption. The term is also used metaphorically to describe information, writing, or content that is easy to understand or process. Etymology traces to Latin digestus, from digerere, meaning to separate or arrange.