Background: Microgravity is associated with an increased of peroxidative. The effect is more pronounced after long duration space flight and can even last for several weeks after landing. Objective: To determine the influence of a simulated microgravity on antioxidant status of the body, 10 healthy volunteers were studied in condition before, during, and just after the simulated microgravity of -6 head -down -tilt (HDT) bed rest for 120 days. We measured the salivary and serum 8-hydroxydeoxyguanosine before, during and recovery of HDT. Results and conclusions: The 8-hydroxydeoxyguanosine showed significant increase in simulating microgravity. The data provides evidence that oxidative stress is among critical nutritional concerns for long duration space travellers.

Key words: Microgravity, 8-hydroxydeoxyguanosine, head -down -tilt