Astronauts Sunita Williams and Butch Wilmore, who have arrived at the International Space Station, may face a number of health problems due to their long stay there, which will not end until February 2025.

One of these health problems is space anemia.

What is space anemia?

Space anemia is a condition in which astronauts experience a decrease in red blood cells while in space.

This phenomenon occurs because the body destroys red blood cells faster than it can produce them when exposed to the microgravity environment of space.

On Earth, our body creates and destroys 2 million red blood cells every second. The findings of a study published in Nature Medicine showed that during a six-month space mission, astronauts’ bodies were destroying 3 million cells per second, 54% more than the normal rate before flight.

NASA explained in its report that this phenomenon begins immediately after the astronaut enters space. The body adjusts to the reduced need for oxygen in microgravity by destroying red blood cells.

However, the body also struggles to maintain balance, leading to a decrease in the total number of red blood cells. This can cause symptoms such as fatigue, weakness, and decreased physical performance due to a condition called anemia (few red blood cells). It can also lead to decreased mental and heart function.

Researchers initially thought the loss of red blood cells in space was due to fluid displacement that occurs when astronauts first arrive in space, causing a temporary drop in blood volume.

But it turned out that the destruction of red blood cells continues not only at the beginning, but throughout the entire space mission.

This destruction, called hemolysis, occurs throughout the duration of the mission and continues to affect astronauts even after they return to Earth, said Guy Trudel of the University of Ottawa, one of the study authors.

The consistently high levels of red blood cells mean that astronauts may need additional nutrition to stay healthy.

These findings suggest that changes in red blood cell control in space could have lasting effects on the health of astronauts.

The discovery of space-induced hemolysis has generated a need for better monitoring and nutritional strategies for astronauts.

It also has an impact on people on Earth suffering from long-term health problems, such as heart patients.

While the body can adapt to some degree over time, space anemia becomes more pronounced upon return to Earth’s gravity. Re-entry into gravity can cause a temporary increase in the destruction of red blood cells, making the condition even worse.

Dr Rahul Bhargava, Principal Director & Chief BMT, Fortis Memorial Research Institute, Gurugram, said the health risks faced by Sunita Williams include bone loss, muscle wasting, cardiac and vision changes.

“The lack of gravity in space can lead to faster bone loss. This is because in microgravity the body does not need as many bones to bear its weight,” Dr Bhargava said.

Without the constant pull of gravity, muscles can weaken and shrink, making it difficult to walk and function when you return to Earth, he said.

As the heart and blood vessels adapt to the microgravity environment, this can cause changes in blood pressure and heart rate, which could increase the risk of cardiovascular problems upon return to Earth.

Some astronauts have complained of vision changes, such as blurriness and nearsightedness, after long stays in space. “The exact cause of these changes is still being studied,” the expert said.

Recovery can take weeks or even months, depending on the length of the space mission.

However, research on space anemia continues to better understand its long-term effects on astronauts’ health. NASA is trying to develop strategies to reduce its impact during extended space missions, such as to Mars or other deep space destinations.