Your body is ground zero for a cellular arms race.
Your mitochondria, red blood cells and immune system rely on iron to function; so do invading viruses and bacteria. As your body evolves safeguards for this most critical resource, these safeguards select for invaders that can overcome them.
“Iron is physiologically useful for catalyzing reactions, such as oxygen binding, because it donates and accepts electrons,” explained Katherine Wander, an associate professor of anthropology at Binghamton University and first of a recent paper on the subject.
“Iron nutrition and COVID-19 among Nigerian healthcare workers” published in the journal Evolution, Medicine, and Public Health. Wander’s 34 co-authors come from Nigerian hospitals and universities; Binghamton anthropology doctoral student Meg Gauck and Zifan Huang, who contributed to the curation and analysis of the knowledge; Mei-Hsiu Che, director of Binghamton Statistical Consulting Services; and Associate Professor of African Studies Titilayo Okoror, who assisted in the investment acquisition and project management.
COVID-19 represented an intriguing opportunity for study. As a novel virus, it had less opportunity to adapt to human physiology – and less time in the evolutionary arms race.
The study focused on healthcare workers in four Nigerian hospitals working in coronavirus wards during the pandemic’s Delta wave. Most of them had Astra Zeneca vaccinations at this point, Wander said.
The body uses iron in a variety of ways, from immune functions to catalyzing reactions in the mitochondria, which produce cellular energy in the form of adenosine triphosphate (ATP).
Iron, famously, is what gives red blood cells their color. Red blood cells use a protein called hemoglobin to transport oxygen. Hemoglobin, in turn, is made of smaller proteins known as heme, which contain an iron molecule that binds and transports the oxygen.
“Our pathogens need iron for the same reasons,” Wander explained. “A virus hijacks the cellular machinery to make more virus. Often, viruses increase the cellular uptake of iron.”
Simply put, naturally high levels of iron provide necessary resources for the body’s cells, but they are also available to pathogens, helping them spread. As a result, we have developed overlapping and overlapping mechanisms for ironing, while pathogens continually develop tactics to triumph over those obstacles.
In an evolutionary sense, the pathogens have the advantage.
“Even at the most productive times, our immune formula adapts as temporally as an organism with a 20-minute generation time,” Wander said, referring to iron sequestration mechanisms. “Bacteria and viruses are capable of generating new generations so temporarily that their evolution occurs more quickly. “
In biological anthropology, the optimal iron theory refers to the so-called “sweet spot” that reduces susceptibility to infections, while primarily meeting the body’s iron needs.
The research in Nigeria showed that individuals with plentiful iron in their system did have a higher risk of catching COVID, as well as people who had anemia. But mild or moderate iron deficiency, however, didn’t seem to protect against infection in and of itself.
The COVID-19 case suggests that even in the early stages of the arms race (when an infectious disease emerges and is still very new to humans) trade-offs in iron nutrition are at play.
“Any additional accumulation of iron will provide potential benefits in terms of immune defense or a possible threat from an infectious agent,” Wander said. “The trade-off is still there, but the sweet spot will be replaced depending on the infectious disease environment. “
This trade-off is potentially one reason why iron deficiency is not unusual even in well-nourished populations, especially women.
The framework has a tendency to conserve iron, recovering 80% of the iron contained in senescent blood cells. However, we are not particularly intelligent when it comes to absorbing iron, and nutritional points can interfere with this process.
“Humans appear to be vulnerable to iron deficiency and we are trying to address this challenge by helping other people consume and absorb iron,” Wander said. “It’s hard to do. “