The longer the time in space, the worse the anemia.
Two million per second. That’s the rate at which a human body on earth destroys and makes red blood cells (RBC). In space, however, the destruction rate is 54% higher: 3 million RBCs are destroyed per second. That’s out of about 20-30 trillion RBCs in the body at equilibrium. Scientists at the University of Ottawa determined these numbers from blood samples from 14 astronauts returning to earth after six months in space.
It’s been known that long tours in space have deleterious effects on astronauts. Despite the happy grins of space travelers enjoying weightlessness, turning somersaults and playing tricks with floating food, each second takes a small toll on the body. Those seconds add up. After lengthy stays in the International Space Station (ISS), astronauts need time to readjust to earth gravity. Videos show astronauts unable to stand to their feet Five of 13 astronauts were clinically anemic when they landed.“Thankfully, having fewer red blood cells in space isn’t a problem when your body is weightless,” said Dr. Trudel. “But when landing on Earth and potentially on other planets or moons, anemia affecting your energy, endurance, and strength can threaten mission objectives. The effects of anemia are only felt once you land, and must deal with gravity again.”
What Happens to the Blood in Weightlessness?
Space anemia has been known for years. Early research on weightlessness suggested it was temporary, and that equilibrium was reached when fluids in the body adjusted to the new environment.
Before this study, space anemia was thought to be a quick adaptation to fluids shifting into the astronaut’s upper body when they first arrived in space. Astronauts lose 10 percent of the liquid in their blood vessels this way. It was thought astronauts rapidly destroyed 10 percent of their red blood cells to restore the balance, and that red blood cell control was back to normal after 10 days in space.
The new research shows that some affects of space anemia are long lasting. The primary effect is an increase in destruction of RBCs. A 54% increase in the destruction rate (measured by amount of carbon monoxide in the blood, created when the heme molecules of RBCs are destroyed) continues throughout the flight. The blood does not recover immediately. In some astronauts the RBC destruction rate was still 30% above normal a year after their flight. The team said, “it’s unclear how long the body can maintain this higher rate of destruction and production of red blood cells.”