Physiological adaptations to space flight.

Over the last 30 years, humans have extended their stays in space from a brief suborbial flight of 15 minutes to an orbital residence of 440+ days. Complex spacecraft now routinely transport humans into an environment more forbidding than any previously encountered. Nutrition can play an important role in counteracting some of the physiological effects of microgravity, and have a profound effect on the quality of life in space. As we embark on extended-duration flights, nutrition becomes a critical issue. This article reviews the physiological adaptations to space flight that affect nutritional requirements.