Nutrition and Liver Health.

Good clinical practice is based on a secure and accurate diagnosis. Poor nutrition is frequently associated with disorders of the liver, and a specific nutrition diagnosis is needed for providing best care and experiencing successful outcome. There is opportunity for better-structured approaches to making secure and consistent nutritional diagnoses in patients with liver disease. Nutrition is the set of integrated processes by which cells, tissues, organs and the whole body acquire the energy and nutrients to retain normal structure and perform the required functions. At the level of the whole body, this is achieved through dietary supply and the capacity of the body to transform the substrates and cofactors necessary for metabolism. All of these domains (diet, metabolic capacity, activity of the microbiome, body composition and the level of demand for energy and nutrients) are influenced by levels of physical activity and can vary according to physiological and pathological disease states. The liver plays a central role in establishing and maintaining these regulated processes. Its capacity to achieve and maintain these functional capabilities is established during one's early life. When these capabilities are exceeded and the ability to maintain the milieu interieur is compromised, ill-health supervenes. Stress tests that assess flow through gateway pathways can be used to determine the maximal capacity and functional reserve for critical functions. The inability of the liver to reliably integrate body lipid metabolism and the accumulation of abnormal lipid are obvious manifestations of impaired regulation both in situations of weight loss, for example, the fatty liver of severe malnutrition, and in situations of energy excess, as in non-alcoholic fatty liver disease. The use of stable isotopic probes and the more recent definition of the variability in the metabolome in different nutritional and pathological states indicate the great potential for clinical tools that would enable a more precise nutritional diagnosis, but these require systematic investigation and application. For the present, approaches that place emphasis on being able to control the metabolic state without exposing the liver to unnecessary metabolic stress remain the basis for successful nutritional support.