Nutritional concerns and possible countermeasures to nutritional issues related to space flight.

The experience obtained in astronauts until now has revealed many nutritional problems during both short- and long-term missions that are still under investigation. When the manned space program evolves to the point where it involves a considerable number of people operating at great distances from the Earth for long periods of time, continuous provision of food as well as physiopathological modifications partly related to nutrition will remain a challenge. Human space missions have outlined the importance of the diet on the quality of an astronaut's life, not only because an appropriate nutritional status can be maintained only through an adequate nutrient intake, but also because food plays an important socio-psychological role.A great amount of research has been done both by the Russian and American teams in order to identify the nutritional requirements for humans during space flights. Crew members should be provided with nutritional adequate diets characterized by many different food items carefully selected according to technological techniques aimed to ensure long shelf-life periods, health, safety, satisfaction and convenience. An astronaut's nutritional status is greatly influenced by important weightlessness, environmental physiological adaptations.Changes in muscle and bone mass, modifications of gastro-intestinal functions and immune alterations may be partly limited by adequate planned dietary countermeasures.