Being in space causes the human body to destroy approximately 54% more red blood cells, leading to a potentially dangerous condition known as anemia. According to a new study, the effects persist even after astronauts return to Earth.
The researchers from the Ottawa Hospital and the University of Ottawa in Ontario, Canada, analyzed breath and blood samples from 14 astronauts before, during, and after their six-month missions aboard the International Space Station. The astronauts’ bodies destroyed approximately 54% more red blood cells than they would on Earth, according to the researchers.
This phenomenon, known as space anemia, was already known to scientists, but they expected it to resolve over time as astronauts’ bodies adapted to the space environment. For the first time, the new study revealed that this is not the case, a finding that could have serious implications for long-term space travel.
“Our study shows that upon arriving in space, more red blood cells are destroyed, and this continues for the entire duration of the astronaut’s mission,” Guy Trudel, a professor of medicine, surgery and biochemistry at the University of Ottawa and lead author of the study said in a statement.
Every second on Earth, the human body creates and destroys 2 million red blood cells. But on the International Space Station, the astronauts’ bodies were destroying closer to 3 million blood cells every second. The results were the same for both male and female astronauts.
Five of the 13 astronauts involved in the study were clinically anemic after their return to Earth; the levels of red blood cells in their blood, as well as the oxygen-carrying component hemoglobin, had dropped so low that other tissues in their bodies were not receiving enough oxygen. Anemia is known to cause fatigue, physical weakness, and dizziness, all of which could be dangerous for astronauts who frequently perform difficult tasks that require concentration, precision, and physical fitness.
Subsequent monitoring revealed that the studied astronauts’ red blood cell levels returned to normal after three or four months on Earth. Even after that time, their bodies were destroying about 30% more red blood cells than before they went to space, indicating that space travel causes long-term changes.
Fortunately, none of the astronauts in the study experienced any obvious health effects from anemia while in space. As a result, the researchers believe that the astronauts’ bodies continued to produce new blood cells during their missions. However, increased red blood cell production necessitates specific nutrients, so future astronauts should take diets that account for this, the researchers said.
This would be especially important on long-duration missions, which, according to a previous study, can result in more severe anemia.
In addition to helping astronauts in staying healthy in space, research on space anemia may one day help people who develop anemia after being bedridden due to an injury or a long illness. Scientists do not fully understand why being bedridden causes the body to destroy red blood cells, as they do with space anemia.
“If we can find out exactly what’s causing this anemia, then there is a potential to treat it or prevent it, both for astronauts and for patients here on Earth,” Trudel said.
The study is the first research published as part of the Canadian Space Agency’s MARROW project, which is examining the effects that being in space have on human bone marrow and blood cells.
The study was published on Friday (Jan. 14) in the journal Nature Medicine.
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