Widespread iron deficiency increases the risk of lung infections

Iron deficiency is a global health problem that increases the risk of respiratory infections, anemia, and other serious diseases. Evidence now suggests that iron deficiency in early childhood may prevent immune cells in the lungs from producing key proteins that are essential for fighting viral infections and establishing immune protection. Notably, this effect appears to persist even after the body’s iron stores have been replenished. As a result, children and adolescents who have experienced iron deficiency may remain more vulnerable to viral infections later in life. These findings come from a new US study conducted at Columbia University Irving Medical Center.

Our immune system is highly specialized and designed to combat a wide range of pathogens. The innate immune system with its proteins, macrophages, natural killer (NK) cells, and other white blood cells provides the first line of defense against most infections. It can also recruit support from the adaptive immune system, which develops after birth and consists of T cells, B cells, and antibodies. The different types of T cells play a particularly important role in fighting viral infections and establishing long-term immunity. Memory T cells enable the body to recognize previously encountered viruses and other pathogens, allowing them to be eliminated quickly and efficiently, often without noticeable symptoms.
The immune system depends on adequate supplies of most vitamins and minerals to function optimally. In the new study, which was carried out on two groups of mice, the researchers focused specifically on T cells and iron. To examine this relationship more closely, one group of mice was fed a diet containing sufficient iron, while the other group received an iron-deficient diet. The mice were then exposed to influenza virus infection.
The study showed that the iron-deficient mice exhibited reduced T-cell activity and developed more severe influenza symptoms compared with mice that had adequate iron levels.
Nevertheless, the iron-deficient mice were still able to generate T cells in the lungs that appeared normal. However, subsequent testing revealed that the ability of memory T cells to produce proteins such as interferon gamma and tumor necrosis factor alpha (TNF-α) was impaired, particularly in lung tissue. Under normal circumstances, these proteins help immune cells recognize and combat infections. The researchers also found that these protein defects caused by iron deficiency persisted even after the mice’s iron stores had returned to normal.
According to the researchers, iron deficiency not only makes it more difficult to fight off an infection. Over time, a history of iron deficiency may also lead to weakened immune memory, causing the immune system to respond inadequately to repeat exposure to the same virus and increasing the likelihood of becoming ill again.
The study was published in The Journal of Immunology.
Going forward, the research team plans to study the immune systems of children in relation to iron deficiency to gain deeper insight into how immune responses can be strengthened. They will also examine the effects of iron deficiency in lung tissue to better understand why low iron stores are associated with chronic lung diseases such as asthma.

• Iron is a key component of hemoglobin in red blood cells, which binds oxygen
• Iron is essential for cellular energy metabolism
• Iron also plays a role in immune function, DNA synthesis, and the health of skin, hair, and nails
• Iron deficiency can occur even in the absence of anemia

Widespread iron deficiency in children requires greater attention

Iron is found in meat, organ meats, eggs, fish, dark green vegetables, legumes, beets, and whole-grain products. Iron from animal sources (heme iron) is absorbed more efficiently than iron from plant sources (non-heme iron). Vitamin C enhances the absorption of non-heme iron, while low stomach acid and excessive calcium intake can inhibit iron absorption.
As a result, children and others who follow predominantly plant-based diets or consume large amounts of dairy products and calcium supplements are at greater risk of iron deficiency.
There is also evidence that overweight children and adolescents are more likely to be iron deficient, which may be due to both suboptimal dietary habits and chronic inflammation that interferes with iron absorption.
It is estimated that around 10 percent of children in the United States have iron deficiency, and since similar trends are observed in other countries, iron deficiency is considered one of the most significant global health challenges early in life.
Although blood tests can detect anemia, which is a late-stage consequence of iron deficiency, the authors of the new study emphasize the need for greater focus on preventing iron deficiency in children and adolescents. This is particularly important because children and teenagers grow and develop rapidly, including the maturation of their adaptive immune systems.
For this reason, it is especially important that children and adolescents consume a healthy, well-balanced diet that emphasizes good sources of iron along with other nutrients that support immune function.

References:

Bradley, M. C et al. Dietary iron deficiency impairs effector function of memory T-cells following influenza infection. The Journal of Immunology. 2025

Columbia University Irving Medical Center. Lack of dietary iron weakens immune response in the lungs. News Medical Life Sciences. 2025

Xiaomian Tan et al. Overnutrition is a risk factor for iron, but not for zinc or vitamin A deficiency in children and young people: a systemic review and meta-analysis. BMJ Global health. 2024