2. Mould: the allergy dark horse

The spores and cell fragments of specific species of fungus like Alternaria, Aspergillus, and Cladosporiumhave been shown to produce particularly powerful allergens. However total spore counts from any relevant species can be just as troublesome if someone is sensitised to them. Mould may thus account for a high proportion of allergy problems particularly in climates that are damp (eg Atlantic coasts of the UK and Ireland, regions around the Netherlands, and any tropical zone around the world) where mould spore levels can be far higher than pollen.

Fungal particles are also inherently more potent than pollen in the airways, because as well as stimulating the usual mast cell IgE response, they can provoke inflammatory cytokine release from white blood cells (macrophages), and so directly cause respiratory inflammation, this typically characterized by neutrophil infiltration and mucosal congestion.

The allergenic potential of fungal spores increases after germination, this more so when the fungus is stressed, for example if dried too quickly (when it is prompted to germinate to ensure survival). Exposure to high levels of fungal spores outdoors (for example in stable and farmyard environments) is particularly linked to lower lung damage and increased airway inflammation (eg ‘farmer’s lung’), particularly in individuals with fungal sensitisation or current asthma.

Antibiotics can play a significant role in driving respiratory allergic responses to fungi by disrupting the gut microbiome, leading to fungal overgrowth (eg Candida) and disturbing immune responses across the body. This disruption promotes allergic airway responses through mechanisms involving affected T-cells, increased levels of eosinophils, mast cells, mucus-producing cells, IgE, and inflammatory cytokines (eg interleukin-5 [IL-5], IL-13, and interferon). This effect is largely independent of genetics and type of antigen. On the other hand beneficial microbiome metabolites, short chain fatty acids (SCFAs), have been shown to reduce these damaging effects.

Common symptoms of mould sensitivity include sneezing, runny or stuffy nose, itchy or watery eyes, and skin rashes. Some people may also experience asthma-like symptoms, such as wheezing or difficulty breathing.

To manage mould allergies, consider the following tips:

• Avoid mouldy areas: stay away as far as possible from damp or mouldy environments, such as basements or rooms with water damage.
• Keep indoor humidity low: use a hygrometer to monitor humidity levels and aim to maintain these below 50%. Use dehumidifiers if necessary but avoid sudden drying as this can stress fungi to produce more spores.
• Ventilation: ensure good ventilation in bathrooms and kitchens to reduce moisture and spore levels.
• Clean regularly: wipe surfaces regularly with mould-killing solutions, and fix any water leaks promptly.
• Air filters: Consider HEPA air filters to reduce airborne spores.

Conventional medications aim to relieve symptoms and include antihistamines or nasal corticosteroids.

We will return to natural approaches in the final post in this section. Not surprisingly given the association between fungi and damp that we saw in the previous chapter, traditional concepts of ‘drying’ remedies were often applied to this situation. Briefly these include liberal use of either warming spices or ‘cooling’ bitters depending on the context. It is also becoming clear again that attention to any disrupted or depleted microbiome could be important. Probiotics could modulate immune responses, reducing allergic airway inflammation by restoring gut microbiota balance and enhancing SCFA production.

Further reading

Sheldrake, M (2020) Entangled Life: How fungi make our worlds, change our minds and shape our futures. Penguin Random House UK. ISBN: 9781784708276