Long COVID might be triggered by low iron levels in the blood from the person’s initial infection, a new study claims.

It’s remained a mystery why an estimated three out of 10 people infected with COVID go on to suffer lingering symptoms like fatigue, shortness of breath, muscle aches and “brain fog” problems with memory and concentration.

In this study, researchers tracked outcomes for 214 COVID patients. They found that ongoing inflammation and low iron levels in blood could be seen as early as two weeks post-infection in those who went on to develop Long COVID symptoms months later.

The low blood iron levels contributed to anemia and disrupted production of healthy red blood cells in Long COVID patients, researchers said.

This could explain why symptoms like fatigue — particularly following exercise — are common in Long COVID, researchers said.

Further, this early iron deficiency was detectable in these patients regardless of their age or sex, results show. Even how sick they became when first infected were didn’t matter, as researchers found similar patterns in the blood following both mild and severe bouts with COVID.

“Iron levels, and the way the body regulates iron, were disrupted early on during SARS-CoV-2 infection, and took a very long time to recover, particularly in those people who went on to report Long COVID months later,” said study author Dr. Aimee Hanson, a senior research associate in genetic epidemiology with the University of Bristol. She worked on the study while at the University of Cambridge.

“Although we saw evidence that the body was trying to rectify low iron availability and the resulting anemia by producing more red blood cells, it was not doing a particularly good job of it in the face of ongoing inflammation,” Hanson added in a Cambridge news release.

Iron deficiency is a natural response to infection and a common consequence of inflammation, explained researcher Hal Drakesmith, an associate professor of immunology with the University of Oxford.

“When the body has an infection, it responds by removing iron from the bloodstream,” Drakesmith said. “This protects us from potentially lethal bacteria that capture the iron in the bloodstream and grow rapidly. It’s an evolutionary response that redistributes iron in the body, and the blood plasma becomes an iron desert.”

“However, if this goes on for a long time, there is less iron for red blood cells, so oxygen is transported less efficiently, affecting metabolism and energy production, and for white blood cells, which need iron to work properly,” Drakesmith added. “The protective mechanism ends up becoming a problem.”

These findings, published March 1 in the journal Nature Immunology, point to possible ways to prevent Long COVID, researchers said.

Doctors could try to control the extreme inflammation that comes with COVID before it can impact blood levels of iron, Hanson said.

Doctors also might try giving patients iron supplements, although Hanson warns that might be too simplistic a solution.

“It isn’t necessarily the case that individuals don’t have enough iron in their body, it’s just that it’s trapped in the wrong place,” Hanson said. “What we need is a way to remobilize the iron and pull it back into the bloodstream, where it becomes more useful to the red blood cells.”

More information

The U.S. Centers for Disease Control and Prevention has more about Long COVID.

SOURCE: University of Cambridge, news release, March 4, 2024

Source: HealthDay