The Effect of a Diet Based on Low Sodium and Slowly Absorbed Carbohydrates on the Incidence of Refeeding Syndrome in Patients With Head and Neck Cancer

Overview

The study is based on a master thesis which showed that 72% of patients with head and neck cancer admitted to a Danish hospital (Rigshospitalet, Copenhagen) developed refeeding syndrome after admission. Refeeding syndrome is characterized by a decrease in plasma phosphate levels, which develops after the reintroduction of an adequate food intake after a longer period of starvation or semi-starvation. This normally happens within 7 days after reintroduction of food. The aim of this study is to minimize the incidence of refeeding syndrome in this group of patients by reintroducing food slowly and by providing a diet low in sodium and high in slowly absorbed carbohydrates as a prevention diet (i.e. given before a potential decrease in plasma phosphate levels appear). Both patients that eat normally, patients with eating tubes and patients with central vein catheters are included in the study, but the data will be evaluated both together and separately.

A large weight loss as a result of a longer period (\>30 days) of starvation or semi-starvation will result in a metabolic adaptation to the decreased food intake. To prevent the degradation of muscle mass into gluco- and ketogenic amino acids to be used for energy production, a shift from gluconeogenesis to lipolysis occurs. Lipids therefore become the primary energy fuel, and the body adapts to use ketone bodies instead of glucose. The reduction in glucose metabolism results in a decreased need for amino acids for use in gluconeogenesis. This means that less amino acids are needed for gluconeogenesis and therefore important muscle mass is preserved. At the same time as the lipid stores are degraded, an intracellular depletion of phosphate, potassium and magnesium occurs. The serum levels of these electrolytes stay within the normal range as long as the body is in the adaptive starvation state. A too quick reintroduction of food to the body will result in a major glucose-induced increase in insulin secretion that will stimulate the transport of glucose, phosphate, potassium and magnesium from plasma into the cells. Because the extracellular blood volume is much smaller than the intracellular, an influx of these electrolytes to the intracellular space will result in a quick and large decrease in the plasma levels. Likewise, an influx of glucose means that it again can enter the glucolysis, and the need for phosphate and the co-factor thiamine, for the production of ATP, will increase. The increased production of adenosine triphosphate (ATP) will activate membrane pumps and reestablish the membrane potential. This means that sodium will be transported from the large intracellular space to the small extracellular, with subsequent fluid retention and edema formation. Therefore a slowly introduced diet low in sodium and high in slowly absorbed carbohydrates might prevent the development of refeeding syndrome.