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Diet and nitrogen metabolism during spaceflight on the shuttle
T P Stein1, M J Leskiw, M D Schluter
1Department of Surgery, University of Medicine and Dentistry of New Jersey, School of Osteopathic Medicine, Stratford 08084, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|July 1, 1996
Summary
Astronauts experience body protein loss during spaceflight. Studies show metabolic adjustments, including altered energy intake and increased protein turnover, help astronauts adapt to the space environment.
Area of Science:
- Human physiology
- Space medicine
- Metabolic research
Background:
- Human spaceflight leads to significant physiological changes, including muscle and protein loss.
- Understanding these adaptations is crucial for astronaut health and mission success.
Purpose of the Study:
- To investigate changes in body protein metabolism during human spaceflight.
- To analyze dietary intake, nitrogen balance, and protein synthesis rates in astronauts.
Main Methods:
- Measurements of dietary intake, nitrogen balance, and protein synthesis rates (using the 15N-glycine method).
- Data collected preflight, during, and post-flight on two Spacelab Life Sciences (SLS) missions (SLS-1 and SLS-2).
Main Results:
- Astronauts experienced initial weight loss followed by stabilization.
- Energy intake decreased significantly during flight, while nitrogen retention was reduced, indicating lean body mass loss.
- Whole body and fibrinogen protein synthesis rates increased during early flight and recovery.
Conclusions:
- Metabolic accommodation to spaceflight involves rapid adjustments in energy intake and nitrogen retention.
- Increased protein turnover suggests a metabolic stress response is key to astronaut adaptation in space.