“Why in the world would you have to be careful with anchovy products? It’s a fish! Not shellfish/ crustacean!” is an all too common sentiment. BUT, as is the case with many things in this world, it’s a little more complicated than that.Shrimp is a common bycatch with anchovy. I first realized this when I bought dried anchovies. And this was more common the smaller they are. The package always says 100% anchovy but if you look closely you can see small shrimp mixed in among them. It becomes more obvious when you start cooking it as the shrimp would turn red. This I’ve experienced myself.
I have also heard people saying for larger anchovy, if you try gutting them yourself, you sometimes find undigested shrimp in their bellies! if this is true it’s an even bigger problem. Anchovies are pretty much out of the picture unless they are big enough to be gutted or you gut them yourself.
Still from personal experience, I seem to be okay with fish sauce (fermented anchovy), and dried anchovy (roughly inch long and larger without unintended shrimp mixed in).
Most are fine. But there was one case where kelp bought at the source had lots of tiny crustaceans attached to it. Other than that I haven’t had any problems with commercial seaweed products.
The minefield of eating out and other randomness
Fermented shrimp paste or broths made with dried shrimp hides in many Asian foods.
An entirely unexpected case where sweet potato starch noodles (supposedly an upgraded version) had chitosan (from crab) in it. All other clear noodles I’ve tried have been fine as they were 100% sweet potato starch.
I got the notion somewhere that since FPIES is not a classic IgE mediated allergy, the sensitivity threshold is likely to be higher. As in, I don’t need to worry about cross contamination, or cooking fumes, and perhaps could even get away with small quantities. This notion hurt me quite a few times.
I don’t know if there is research on such sensitivity levels generally, but my guess is that it is highly individual. Even some lucky(?) people with IgE mediated allergy can have high thresholds approaching almost a serving of the offending food.
For me, the provocation dose seems low enough that practically speaking I need to avoid my triggers strictly to avoid symptoms. But I can afford to take small risks with cross contamination as trace amounts are unlikely to cause the full blown reaction. It can still make things pretty miserable with multiple trips to the bathroom, etc.
My issue with shrimp perhaps shows an example of the sensitivity level possible with FPIES. If I actually eat a piece of shrimp, pain starts after about a half hour and the most severe symptoms of shock and vomiting occur in about two hours. About a teaspoon of fermented shrimp in soup caused similar reactions that were just a tad milder and delayed and peaking in about four hours. In another incident I had trace amounts of shrimp in broth for dinner and became increasingly uncomfortable during the night with extreme abdominal distension. I could barely sleep and by morning I couldn’t get into my clothes and looked perhaps 6~7 months pregnant. Finally at mid morning diarrhea started and I spent the next hour taking ten plus trips to the restroom. For the next couple of days I had tiny bumps all over my skin. But on the bright side, I didn’t have to fear death with the shock or vomiting.
The pattern I’ve noticed is that the smaller the quantity the more delayed the symptoms. And while they are a tad milder they can still be pretty severe. So it seems for all intents and purposes any and all form of shrimp must be avoided.
I am not sure whether this allergy happened to be newly emerging at the time, as it is quite common for shellfish or other seafood allergies to develop in adulthood. The incidents that made me suspicious were due to small amounts of fermented shrimp paste. It was a strong suspicion before going into allergy testing but when the skin prick test came out negative I made the mistake of eating a few actual plump pieces of shrimp and suffered immensely for it.
Even after this I made a (turns out mistaken) assumption that since this is not an IgE mediated allergy, I might tolerate small amounts of it. If you can tolerate a tiny amount, or a small amount of fermented shrimp, a lot more options open up especially if you are into Asian foods. Alas, it was not to be.
Later incidents informed us that I react badly to even small amounts of fermented shrimp and undetectable levels (at least by eye and taste) of dried shrimp used to make broth.
Delayed tiny bumps all over skin
Skin prick test
Possible connection with dust mite allergy (positive) as a trypomycin cross reactivity issue
With a 75% chance to cross react, I have not taken the risk