Iron Physiology and Its Impact on Atopic Diseases: An EAACI Taskforce Report

Area of Science:

• Immunology
• Nutritional Science
• Allergy Research

Background:

• Iron is vital for oxygen transport, metabolism, and immune function.
• Iron deficiency is a widespread global health issue, affecting nearly 25% of the population.
• Nutritional immunity, a defense mechanism involving iron redistribution, can be triggered by iron deficiency, leading to increased illness.

Purpose of the Study:

• To review normal iron physiology, absorption, and distribution.
• To examine the impact of iron deficiency on various body compartments, particularly type 2-driven diseases.
• To explore the link between iron status and allergic conditions.

Main Methods:

• Literature review of iron physiology and deficiency consequences.
• Analysis of epidemiological data on iron deficiency and allergies.
• Examination of clinical evidence on iron repletion in allergic individuals.

Main Results:

• Iron deficiency disrupts immune homeostasis, promoting type 2 inflammation, elevated IgE, and mast cell/eosinophil activation.
• Regulatory macrophages adopt an inflammatory, iron-sequestering state, exacerbating malabsorption.
• Epidemiological studies link higher iron deficiency risk to allergic individuals, with early-life iron deficiency predisposing to eczema, wheeze, and asthma.
• Restoring iron status through diet, supplementation, or fortification has been shown to lower IgE, improve lung function, and reduce allergic symptoms.

Conclusions:

• Iron deficiency significantly impacts immune regulation and is closely associated with the development and severity of allergic diseases.
• Restoring iron status presents a potentially modifiable factor in managing type 2 allergic conditions.
• Integrating iron assessment and nutritional care into allergy management strategies may decrease disease burden and progression.