If you have allergies : beware of coffee !

At the hospital for a consultation on my teenage daughter's polyallergies and their relation to her eosinophilic esophagitis (EoE, yes, she's spoiled), we had a discussion with her allergologist about completely stopping allergens and inflammatory foods (rich in histamine, for example) to achieve remission. This disease is like internal eczema; it's a lifelong condition with phases of remission and exacerbation, but it can have immediate consequences such as choking or near-complete closure of the esophagus.

I was playing Sherlock Holmes with anything that could be inflammatory. I joked that she should also stop drinking coffee, which she loves and occasionally dinks, or eats in cakes (not great for ADHD either!). Our allergologist told us that we should probably stop anyway, given everything found in coffee. She then cited the case of one of her patients who was allergic to coffee... but not actually to coffee. You'll understand.

Coffee Allergy

True allergy to coffee proteins is rare and mainly affects workers who handle coffee daily. In this case, coffee dust maximizes the inhalation of the allergen (like some bakers allergic to flour), with mostly skin and respiratory symptoms. There is also a rare and severe case of combined anaphylaxis involving coffee beans coated with arabic gum, consumed whole. So, what's the deal with my daughter?

Cross-Contamination with Coffee

Could it be cross-contamination? When ordering coffee, the machine may be used for various preparations. These can leave residues if the machines are not carefully cleaned.

There's the issue of coffee mixed with cereals (allergies to wheat, rye, buckwheat). Also, milk frothers used to heat milk or prepare cappuccinos with nut milks (almond, hazelnut), soy milk, or oat milk. This is also a problem if you're allergic to cow's milk.

Therefore, it's important to be vigilant when you have allergies—and this applies to children drinking hot chocolates prepared with machines using these different "milks" or drinks. However, while problematic, these allergies are sporadic and related to visiting public places. So, what could be problematic at home and daily?

Coffee Contaminants and Their Allergenic Effect

Yes, there might be something worse. If you are allergic and/or asthmatic and/or have eczema, i.e., atopic, you have a 20-30% chance of being allergic to cockroaches, which is 5% of the general population. But wait, you might ask. What does this have to do with my morning coffee? The one I prepare at home, carefully chosen, maybe even organic and responsibly sourced? I'm getting to that, and it's not pretty.

Would you like some more cockroach in your morning ground coffee?

On average, 10% of green coffee beans are contaminated with cockroaches (according to this study), even organic coffees. This means these will be ground with your coffee powder. You might say, after the initial disgust, that the cockroach is cooked during roasting and that it adds protein (after all, there's talk of eradicating world hunger with insect flours).

But... if you're allergic to cockroaches, you're allergic to their proteins!

Oops. This might explain certain symptoms, such as rhinitis, asthma, stomach aches, or more severe reactions after drinking my cockroach infusion... I mean, my coffee.

Be cautious if you are allergic to certain foods or creatures. Cross-allergies between dust mites and cockroaches are due to a common protein called tropomyosin. This protein is present in dust mites, cockroaches, other insects, and certain shellfish like shrimp, crabs, and mollusks such as snails and oysters.

This means that people allergic to dust mites and these foods may also react to cockroaches and vice versa, due to the similarity of the allergens... so, to our ground coffee!

And that's not all...

Contaminants found in coffee mainly include pesticides used during cultivation and storage, mycotoxins like ochratoxin A (OTA) that develop due to unfavorable environmental conditions, and polycyclic aromatic hydrocarbons (PAHs) formed during drying and roasting processes (the same ones that are toxic in very toasted bread, fries, etc., due to the famous Maillard reaction above 120°C).

Biological residues can include molds and bacteria, notably toxic fungal species like Aspergillus and Penicillium, which can contaminate coffee beans and processing facilities, and whose spores can cause respiratory symptoms. Yum.

So, can you do without coffee? If it's difficult, at least opt for whole bean coffee that you grind yourself, or even rinse, with limited roasting (Arabica) and, if possible, keep your equipment to yourself to avoid cross-contamination.

From there, carrying your own covered mug, American-style (this is rare in Europe!), is just a small step. Or completely switch to tea!