NUTRITION AND HUMAN PHYSIOLOGICAL ADAPTATIONS TO SPACE-FLIGHT

Space flight provides a model for the study of healthy individuals und ergoing unique stresses. This review focuses on how physiological adap tations to weightlessness may affect nutrient and food requirements in space. These adaptations include reductions in body water and plasma volume, which affect the renal and cardiovascular systems and thereby fluid and electrolyte requirements. Changes in muscle mass and functio n may affect requirements for energy, protein, and amino acids. Change s in bone mass lead to increased urinary calcium concentrations, which may increase the risk of forming renal stones. Space motion sickness may influence putative changes in gastrointestinal-hepatic function; n eurosensory alterations may affect smell and taste. Some or all of the se effects may be ameliorated through the use of specially designed di etary countermeasures.