Fish and Shellfish Allergens in Alaska Seaweed: a play
Setting
Seaweed grows in the sea.
In the course of it’s life, it may naturally become habitat for creatures — namely fish, crustacean, and molluscan — that find themselves interacting with the seaweed through their typical aquatic activities. Unfortunately(!), this presents a risk of contamination of the seaweed with two of the eight (or 9) major allergens: fish and shellfish. We are set in the sea.
Stage
Undeclared allergens are bad.
“Allergens” are specific types of protein commonly found in the high risk food groups. It’s a major part of Quality, and a reason why we must ‘sanitize’ (which denatures the protein). Does seaweed, with its proximity to fish and shellfish, present a risk of allergens?! We find ourselves in a trial.
Cast
Three characters: Samples, Testing, and Analysis
Samples is a collection of seaweeds from the 2025 Alaska Seaweed Tissue Analysis project. This includes many species of wild and cultivated seaweed that was collected, immediately frozen, mailed to another facility (Kodiak Seafood and Marine Science Center), meticulously dried and homogenized (I watched a very competent Belgium man do this), partitioned (3 replicates), and mailed to an ISO 17025:2017 laboratory for testing (Foodmetrics). In total, 61 samples were collected, 366 data points.
Testing is the measurement of specific allergens. The standard method of quantification uses ELISA targeted at indicator allergen molecules. This study measured fish (parvalbumin) and shellfish (tropomyosin) levels in all the samples. The results were reported as ppm (or ppb) of the allergen within the material. Analysis will determine the allergen risk of Samples.
Analysis is a critical examination of Samples and Testing. This requires some numbers and targets. A very fun report (Mildenberger and Rebours’ banger: Marine allergens in farmed seaweed: considerations for precautionary labelling) provides some insight. They describe how the “Voluntary Incidental Trace Allergen Labelling” (VITAL) program proposes a threshold of 25 mg for crustacean protein and 1.3 mg for fish protein as the point where 1% of the allergic population would react with objective allergic symptom, AKA where the most allergic people have an allergic reaction. We have a target for Testing and Samples to try and acheive.
Scene
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Testing measures Samples using two ELISA methods at an accredited lab. The results are captured in an encrypted Certificate of Analysis, stored in an archive (cloud-based, obviously), and digitized for Analysis. All data is available from the on-line open-access data server: SeaweedDatabase.org
“I suppose you think these look pretty good,” Testing remarks. Breath thick from a night of data collection, Testing looks weary and exhausted.
“Let me ask you question,” Samples replies as 183 dried seaweed replicates in unison. “Would you agree 5 grams is a suitable serving size for seaweed?” (5 g dry equivalent ~50 g fresh… a healthy serving for many applications).
“I suppose that is a reasonable value,” Testing agrees. Testing is by no means unreasonable. “The FDA GRAS notification GRN 000123 estimates daily consumption of kelp (as Laminaria japonica) in Japan as 3.6 grams per day.”
“A conservative threshold dose for shellfish and fish allergen are 150 ppm and 1000 ppm, respectively, if 5 dry grams are to be consumed,” Analysis booms authoritatively. Imagine that scene in the Wizard of Oz where they first meet the Wizard.
“If you look at all wild and farmed Samples collected,” Samples begins, having taken sort of centre stage in our sea-trial. “Crustacean allergen was below 150 parts per billion in all samples and fish below 25 ppm. These values are well below that threshold limit!” Everyone cheers.
“Well this certainly is a convincing data point,” Testing admits. Samples has made a compelling case. [End Scene]
Conclusion
Our actors have certainly revealed some information about wild and cultivated seaweed. Our admittedly simple experiment (Sample) and lax scientific rigour (Testing) must not be discounted, but the data suggested low levels of allergens in all samples. If a typical amount of this seaweed is consumed, there is no reason to expect an undesired allergenic outcome (for fish/shellfish sensitive individuals). Of course, there are many process steps with risk of undeclared allergenic exposure, but for seaweed, Analysis showed it can be effectively controlled from the on-set (perhaps with raw material handling and receiving practices).
Epilogue — Can we ever be truly Allergen-free?
I have spoken (and/or emailed) with a handful of representatives from various “allergen-free” designation services.
Allergen-free can be an important claim and fit within many trendy categories that could benefit from minimally processed seaweed ingredients. I have a common adage: “any is too many.” This seems to be the practice of the certifiers I spoke with. Despite how low the results indicate the allergen load is on seaweed, any is to many for allergen-free.
Companies use the “May Contain” statement, also known as precautionary labelling. This study suggests seaweed can be handled to fish and crustacean allergen levels below those of risk to allergenic individuals. One must consider the amount of people who have reported an adverse fish or crustacean allergic reactions. To my knowledge that number is zero.
So, while not allergen-free, pretty manageable allergen risk. I would consider periodic Testing of representative Samples combined with detailed Analysis as a suitable practice, a framework described here.
