Astronauts destroy 54% more red blood cells in space

A study claimed to be the first of its kind has shed new light on the dangers posed by spaceflight and the impacts on red blood cell counts for astronauts on long-duration missions. The research deepens our knowledge of a condition known as “space anemia” and has important implications for the future of space exploration.

“Space anemia has always been reported when astronauts have returned to Earth since the first space missions, but we didn’t know why,” said lead author Dr. Guy Trudel of the University of Ottawa. “Our study shows that when arriving in space, more red blood cells are destroyed, and this throughout the duration of the astronaut’s mission.”

Space anemia was thought to be a transient, short-term condition resulting from the body’s adaptation to the space environment, with fluids moving up the astronaut’s body upon arrival due to the lack of gravity . This causes them to lose 10% of the fluid in their blood vessels and it had been assumed that their body quickly destroyed 10% of red blood cells to keep things under control, with blood cells replenished to normal levels after 10 days in space.

What Trudel and his team discovered is that the effects last much longer and that the destruction of red blood cells is not the result of moving fluids, but simply of being in space. Scientists directly measured the destruction of red blood cells in 14 astronauts participating in six-month space missions, by analyzing their breath. Specifically, they measured the amounts of carbon monoxide in the breath samples, because a molecule of carbon monoxide is produced each time a molecule of heme, a component of red blood cells, is broken down.

This revealed that the astronauts were destroying three million red blood cells every second during their six-month stay on the International Space Station. That’s 54% more than the two million our bodies destroy and replace every second on Earth, with the effects seen in both male and female astronauts. Although direct measurements of red blood cell production were not taken, the team assumes that the lost cells were quickly replaced, otherwise the astronauts would have developed severe anemia.

Nevertheless, five out of 13 astronauts were clinically anemic when they landed on land, while one did not have a blood test. Red blood cell levels were found to gradually return to normal levels three to four months later, but interestingly measurements taken a year after the astronauts returned showed destruction was still 30% greater. higher than usual.

“This is the best description we have of red blood cell control in space and after returning to Earth,” Trudel said. “These results are spectacular, given that these measurements had never been done before and we didn’t know if we were going to find anything.”

According to the scientists, the results suggest that astronauts or space tourists should be screened for conditions that might be affected by anemia, and diets might need to be adjusted to account for the additional loss of red blood cells. Crucially, it’s also unclear how long the body can sustain this higher rate of destruction and production of red blood cells, and scientists have yet to determine the exact biological mechanisms behind it.

“If we can find out exactly what’s causing this anemia, then it’s possible to treat or prevent it, both for astronauts and for patients here on Earth,” Trudel said.

The research was published in the journal Natural medicine.

Source: University of Ottawa

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