Low Iron and Immunity: Does Iron Deficiency Affect Your Immune System?

The role of iron in immune function

Low iron (iron deficiency) is commonly linked to fatigue and is one of the most common nutrient deficiencies, particularly in plant-based diets (see: Vegan Diet Deficiencies: Common Nutritional Gaps and How to Prevent Them). The relationship between low iron and immunity is increasingly recognised, with emerging research suggesting it may affect immune function by impairing the body’s response to infection and disrupting inflammation regulation.

Iron plays a key role in immune cell activity and pathogen defence. When levels are too low or become disrupted, this can impair how effectively the body responds to infection and maintains immune balance (Nairz et al., 2014; Camaschella et al., 2020).

It may also influence gut immunity – an area increasingly recognised as important for overall immune health.

Does low iron affect the immune system?

Yes – iron is essential for normal immune function.

Low iron levels can:

• reduce immune cell activity
• weaken the body’s response to infection
• disrupt the regulation of inflammation

Low iron levels can impair these processes, potentially increasing susceptibility to infection and affecting how the immune system responds (Drakesmith et al., 2021).

How iron deficiency may affect immunity (simplified)

• Iron deficiency → reduced immune cell activity → impaired pathogen response → increased infection risk
• Iron imbalance → altered gut microbiota → disrupted gut barrier → increased immune activation
• Disrupted iron regulation → altered inflammatory signalling → difficulty resolving inflammation

Low iron levels are also associated with:

• Reduced gut barrier integrity – allowing unwanted substances to trigger immune responses
• Altered immune regulation – under- or over-active immune responses
• Changes in gut microbiota – shifts that influence immune function

Why does the body lower iron during infection?

During infection, the body actively reduces the amount of circulating iron.

This process is known as nutritional immunity – a protective response that limits iron availability to bacteria and pathogens that rely on it to grow (Nairz et al., 2014).

While helpful in the short term, this response may also create trade-offs by temporarily restricting iron needed for optimal immune function.

What is nutritional immunity?

Nutritional immunity is the process by which the body reduces circulating iron during infection to limit the growth of bacteria and pathogens (Nairz et al., 2014).

Deeper mechanisms: how iron influences immune function

Beyond its role in basic immune function, emerging research suggests that iron may influence the immune system at a deeper level – including gut immunity, cellular signalling, and inflammatory control.

1. Iron and gut immune function

Iron plays a role in regulating immune cells in the gut, including those involved in maintaining the intestinal barrier and regulating immune responses (Ribeiro et al., 2021).

These cells help:

• maintain the integrity of the gut barrier
• distinguish between harmful pathogens and harmless substances

A well-functioning gut barrier is essential for preventing unnecessary immune activation.

Disruptions in iron levels are linked to:

• Reduced barrier integrity – allowing substances to pass through more easily (Camaschella et al., 2020)
• Altered immune responses – under- or over-activation of immune pathways (Nairz et al., 2014)
• Changes in the gut environment – shifts in gut microbiota that influence immune function (Abbas et al., 2022)

In simple terms: iron helps maintain gut stability and prevent inappropriate immune activation.

2. Iron and immune signalling

Iron is involved in key cellular signalling pathways that regulate how immune cells behave (Li et al., 2020).

These pathways control:

• communication between immune cells
• activation in response to threats
• resolution of inflammation

Disrupted iron levels are associated with:

• delayed or weaker immune responses
• excessive inflammatory activity
• difficulty resolving inflammation

In simple terms: iron helps fine-tune how strongly and how long the immune system responds.

3. Iron and immune balance

The immune system requires balance – activating when needed and calming down afterwards.

Iron plays a role in maintaining this balance (Camaschella et al., 2020).

Disruptions in iron metabolism have been linked to:

• chronic inflammation (Weiß & Ganz, 2014)
• immune dysregulation
• impaired immune tolerance

In simple terms: iron may help stabilise immune responses and prevent overreaction.

Can low iron make you get sick more often?

Research shows that low iron levels are associated with increased susceptibility to infection (Abuga et al., 2023).

However, this relationship is complex and depends on multiple factors, including overall health, diet, and immune status.

What this means in practice

While iron deficiency is often overlooked in immune health, its role in regulating inflammation and gut-immune interactions suggests it may have broader implications than traditionally recognised.

Low iron levels may influence:

• how often you get sick
• how quickly you recover
• how balanced your immune response is

However, iron is just one part of a much larger system that includes:

• diet
• sleep
• stress
• gut health

Emerging evidence suggests that disruptions in iron status and gut-immune interactions may contribute to immune imbalance. While not a direct cause of autoimmune disease, this may, in susceptible individuals, help create conditions in which autoimmune processes can be triggered (Weiß & Ganz, 2014; Abbas et al., 2022).

Supporting healthy iron levels

Maintaining healthy iron levels is likely beneficial for overall health and immune function.

For those following a plant-based diet, particular attention may be needed, as plant sources of iron are less easily absorbed (Hallberg & Hulthén, 2007).

Strategies include:

• including iron-rich foods such as lentils, beans, tofu, and leafy greens (see: Vegan Iron-Rich Foods: Top Plant Sources Ranked by Iron Content)
• combining iron-rich foods with vitamin C to enhance absorption
• avoiding tea or coffee with meals

What to take from this

Iron plays a more complex role in the immune system than previously understood.

While research is still emerging, it is becoming clear that iron may influence:

• gut immune function
• immune signalling
• inflammatory balance

Maintaining healthy iron levels may therefore support not just energy – but overall immune resilience.

Summary: Does low iron affect the immune system?

Yes. Iron deficiency can impair immune cell function, weaken the body’s response to infection, and affect inflammation and gut health. While the relationship is complex, maintaining adequate iron levels is important for overall immune resilience.

FAQs

References

Nairz M et al. (2014). Iron at the interface of immunity and infection. Frontiers in Pharmacology. https://doi.org/10.3389/fphar.2014.00152

Camaschella C et al. (2020). Iron metabolism and iron disorders revisited in the hepcidin era. Haematologica. https://doi.org/10.3324/haematol.2019.232124

Drakesmith H et al. (2021). Vaccine efficacy and iron deficiency: an intertwined pair? The Lancet Haematology. https://doi.org/10.1016/S2352-3026(21)00201-5

Ribeiro M et al. (2021). Oral iron supplementation in patients with chronic kidney disease: Can it be harmful to the gut microbiota? Nutrition in Clinical Practice. https://doi.org/10.1002/ncp.10662

Abbas M et al. (2022). Effects of iron deficiency and iron supplementation at the host-microbiota interface: Could a piglet model unravel complexities of the underlying mechanisms? Frontiers in Nutrition. https://doi.org/10.3389/fnut.2022.927754

Li Y et al. (2020). Regulation of iron homeostasis and related diseases. Mediators of Inflammation. https://doi.org/10.1155/2020/6062094

Weiß G & Ganz T (2014). Iron and inflammation: a delicate balance. Nature Reviews Immunology. https://doi.org/10.1038/nri3681

Abuga K et al. (2023). Severe anaemia, iron deficiency, and susceptibility to invasive bacterial infections. Wellcome Open Research. https://doi.org/10.12688/wellcomeopenres.18829.1

Hallberg, L., & Hulthén, L. (2007). Biological factors involved in iron absorption. International Journal for Vitamin and Nutrition Research, 77(4–5), 293–298.