Can those with fish allergies take fish supplements?

This is a question I often get from clients and this answer is slightly longer than planned but I hope it answers some of your questions.

Are fish oil supplements safe for people with fish allergies?

That is a difficult question to answer. I can find only one paper published on this topic. In 2008, the Allergy Team from Missouri skin prick tested (SPT) 6 fish allergic individuals with 2 different fish oil supplements and the participant then underwent an oral food challenge (OFC). None of the participants showed a positive SPT or OFC – when meant that they all safely tolerated the fish oil supplements. Both of these carried a warning “not suitable for fish allergics”.

In contrast to this, a team from Canada reported on a case where a crab allergic individual showed recurrent episodes of anaphylaxis to a fish oil supplement. This is slightly difficult to interpret as the major allergens in fish (parvalbumin) and shell fish (tropomyosin) are different. No cross-reaction between these two allergens is seen, despite the fact that fish and shellfish allergies often co-exisit.

Why do most fish oil supplements carry a warning for fish allergy?

I contacted a number of fish oil manufacturers, none of which were willing to state that their fish oil supplements are safe for fish allergic individuals or that their krill oil supplement is safe for shellfish allergic individuals. Some of the manufacturers stated the product was not safe for anyone with seafood allergies.

I then contacted my resident expert on allergens to help out (tweet as @ad_rogers).

He stated that oil matrices can be difficult to analyze but the product could still be tested for total protein content. Most immune-assays will only detect (cod) parvalbumin in fish and tropomysin in shellfish. Detection of the parvalbumin becomes more difficult in fatty fish, and these two proteins (parvalbumin and tropomyosin) do not cover all the allergens in seafood. It therefore seems that at this point in time, it may not be possible to declare that fish oil supplements are safe for fish allergic individuals and krill oil supplements for shellfish allergic individuals.

Another point to take into account that the techniques used to measure the protein content of food for nutritional purposes, differ from detecting allergenic proteins. Just because a product indicates 0 grams of protein, does not mean traces amounts of allergenic proteins are not present.

If you are fish allergic only and want to take a krill oil supplement or shellfish allergic only and want to take a fish oil supplement, I suggest you discuss this with your physician or registered dietititan (RD).

Is there an alternative?

Algal oils contains* both EPA and DHA and are therefore a suitable alternative to fish/krill oil. Some, however, contain only DHA and it is therefore important to choose a supplement that contains both. REMEMBER: Always check the label and ask the manufacturer if the product is safe for fish and shellfish allergy suffers.

 I recommend that you discuss the use of supplements with your physician. A registered dietitian (RD) is a great resource to help you find a supplement that suits your nutritional (and allergen) needs. 

Want to know more about why we need fish oil/omega-3 supplements and how much? My next question deal with this; covering international guidance.

Please feel free to comment in you are in fact taking a fish/krill oil supplement despite being allergic to these. Please let us know if you know of a supplement that is guaranteed to be safe by the manufacturer.

Carina Venter PhD RD

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