Fungus and Food Allergy

Mold allergy is one of the most common airborne allergies seen in Singapore due to its humid tropical weather. Intriguingly, some who suffer from mold allergy may have concurrent food allergies as well. In this article we strive to discuss on mold allergies, the cross-linkage with certain food proteins, and what we can do to mitigate both fungus and food allergies.

Airborne Mold and Fungus

Fungi thrive well in environment which is warm, moist and high in humidity- such as tropical, heavy rainfall weather.  Inhalant fungi are one of the most common causes of allergy seen in tropical country. Fungal spores can be found both indoor and outdoor, commonly on walls, ceilings, air conditioners, plants, vegetation and even soil. Common fungi that are associated with allergic diseases include Alternaria alternata, Aspergillus fumigatus, Cladosporium herbarum, Penicillium spp, Candida spp and etc.

Airborne fungi can cause adverse health reactions via

• Inhalation of the fungi/ spores 
• Direct toxic and infection effect from the fungi
• Invasion of the body system as an opportunistic pathogen in those who has compromised immune system

In the case of allergy, repeated exposure to fungi through inhalation or even direct skin contact can result in sensitization of the body’s immune system and presentation of allergy conditions such as respiratory allergic conditions (rhinitis/sinus disorders, allergic asthma, allergic bronchopulmonary aspergillosis), skin allergic disorders (hives, atopic dermatitis).

The Mechanism of Allergy towards Fungus

The proteins found in the fungal spores and hyphae contribute to allergic reactions. 

One can be exposed to fungal spores and hyphae via breathing, eating, or even direct touching.

Following exposure to the fungal allergen protein, the body immune cells will become sensitized, and they will develop immunoglobulin E (IgE) antibodies and a cascade of immune cell response, resulting in a pro-inflammatory state that is seen as allergy symptoms clinically.

Edible Fungus Allergy: Cross-Reactivity to Airborne Fungi Allergy

Some fungi are edible and have great health benefits. They are rich with micronutrients, have anti-microbial properties to our human body and do not contain cholesterol. These edible fungi include mushroom, agaric, Tuckahoe root, Cordiceps sinensis, mycotoxin etc.

Fungus-food allergy syndrome (FFAS) is a unique allergic condition whereby the body’s immune system mistakenly recognized the similarity of proteins in both fungus and food as allergens and mounts an inflammatory allergic response following consumption of certain edible fungi. The cross-reactive nature of symptoms between airborne fungi and food fungi are due to the similar protein structure found among these 2 fungi.

The affected person has to be firstly exposed and sensitized towards fungi protein allergen (commonly via inhalation), then with secondary exposure to similar fungi protein allergen (via consuming food fungi) leading to FFAS. 

What are the symptoms of Fungus-food allergy syndrome (FFAS)?

The symptoms of FFAS can range from non-specific gut symptoms to full-blown allergy reaction.

	FFAS Symptoms
Oral/ Mouth	Itchy and swelling of lip/ tongue/ mouth/ throat
Gut/Intestine	BloatednessAbdominal crampsNausea and vomitingDiarrhea
Skin	Itchy whealsRed eczematous rash
Respiratory	Snuffly nose, watery eyesCoughShortness of breathwheezing
GeneralizedIn such situation (anaphylaxis) one should seek medical attention immediately as it can be fatal if there is any delay in treatment.	Feeling of impending loomDizzy and faintyDifficulty breathingTightening of airwayFacial swellingWidespread rash throughout the body

What are the common edible fungus or food that can trigger Fungus-Food Allergy Syndrome?

Macro-fungus such as mushroom can trigger FFAS. 

Food that has fermented fungi can also cause FFAS in affected individuals.

Food such as blue cheese, fermented soybeans, miso, tempeh and shoyu contains fermented fungi. Alcohol drink such as beer, cider, wine requires fermented yeast for drink brewing. Cured sausages or dry Catalonian sausage contains fermented fungus as well. 

Interestingly, although spinach or kiwifruits are not a type of fungus, airborne fungus can elicit an allergic response in susceptible individuals who consume these citrus fruits or vegetables.

Certain allergic symptoms may improve with ‘heated or cooked’ edible fungus- such as in the case of baked bread, heated alcohol drink due to inactivation and denaturizing of the allergen proteins under high heat. With the allergen proteins broken down, the immune system will not be triggered even though one is 'exposed' to the culprit food.

How can I diagnose fungus and food allergy?

A good clinical history with known airborne fungi allergy and subsequent inducible allergic symptoms following certain food consumption is suggestive of fungus and food allergy. Nonetheless, a good history is always challenging and often much confusing in real life.

Allergy tests in Singapore can guide both affective individuals and physicians in narrowing down or ruling out the possibility of fungus and food allergy:

• Skin prick test: A quick 20-30 minutes test to evaluate for any skin reaction following direct skin exposure of the allergen (fungi)
• RAST IgE blood test: A detailed report on the antibodies that one develops following exposure and allergic to certain food/airborne allergens (food or airborne fungi)
• Food challenge test: Useful in re-producing allergic symptoms following exposure to culprit food fungi. It may not be widely available and test should be offered cautiously due to risk of allergic reactions.

What is the treatment for fungus and food allergy?

• Identifying and avoiding the culprit allergens are imperative in managing fungi and food allergy.
• Food diary can be useful in monitoring for any common food denominators that trigger the allergy symptoms.
• An individual dietary recommendation may be required for certain food that may cross-react with background airborne fungus allergy.
• Lifestyle advice with keeping living space well ventilated, opening the windows (if possible), using humidifier in close-up region, anti-mold paint/wash can be considered to reduce colonization of fungus in our living environment. 
• Antihistamines, steroid or adrenaline (in the case of anaphylaxis) are common medications used in management of allergic symptoms.

Role of immunotherapy in fungus and food allergy

Allergen specific immunotherapy (AIT) can be used to re-educate and de-sensitize those with airborne fungi allergy. The concept of immunotherapy revolves around repeatedly re-challenging the immune system with daily exposure to the triggering allergen, in hope of down-regulating the immune response and resolution of allergic symptoms.

Current medical evidence remains sparse though there are potential benefits for AIT treatment in FFAS. While current AIT treatment is focusing on air-borne related allergies rather than food allergy per se, interestingly, by managing the airborne allergies, one may notice improved tolerance towards edible fungus.

If you’re experiencing persistent symptoms that may be linked to a fungal infection or food allergy, it’s best to seek professional advice. Our specialists can help identify the cause and guide you towards effective allergy treatment options. Book a consultation today to get started.

References: 

1. Ogidi OI, Oguoma LMO. Allergies and Sensitivities Associated with Edible Mushroom. Springer Nature. 2025 Feb 4; p1-28.
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4. Xing H, Wang J, Sun Y, Wang H. Recent Advances in the Allergic Cross-Reactivity between Fungi and Foods. J Immunol Res. 2022 Oct 7;2022:7583400.
5. Hernandez-Ramirez G, Barber D, Tome-Amat J, Garrido-Arandia M, Diaz-Perales A. Alternaria as an Inducer of Allergic Sensitization. J Fungi (Basel). 2021 Oct 7;7(10):838.
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