Novel food information: Head-on-Gutted AquAdvantage salmon

On this page

Background

Health Canada has notified AquaBounty Canada Inc. that it has no objection to the food use of the Head-on-Gutted (HOG) form of AquAdvantage salmon (AAS). The Department conducted a comprehensive assessment of HOG AAS according to the Codex Alimentarius Guideline for the Conduct of Food Safety Assessment of Foods Derived from Recombinant-DNA Animals. These guidelines are internationally accepted principles for establishing the safety of foods with novel traits.

The following provides a summary of the notification from AquaBounty Canada Inc. and the evaluation by Heath Canada and contains no confidential business information.

Introduction

AAS are Atlantic salmon (Salmo salar) that have been genetically modified (GM) to grow more rapidly. AAS contains the protein coding domain of a growth hormone (GH) gene from Chinook salmon and the regulatory sequences of an antifreeze protein (AFP) gene from the ocean pout. The integrated GH transgene allows AAS to grow more rapidly during early-life and therefore reach market size sooner. As adults, AAS are not larger than their non-transgenic comparators.

On May 19, 2016, Health Canada informed AquaBounty Canada Inc. that it had "No Objection" to the sale of the fillets comprised of the muscle-skin of AquAdvantage salmon as described in their 2012 novel food notification (NF-263). In November 2022, a novel food notification was received regarding the acceptability for food use of the Head-on-Gutted (HOG) form of AquAdvantage Salmon (AAS) which was not included as part of the previous safety assessment. The substantive change between the fillets comprised of muscle-skin and the current product in Head-on-Gutted form, is the presence of not only muscle and skin, but also bone and brain.

The safety assessment performed by Food Directorate evaluators was conducted according to the Codex Alimentarius Guideline for the Conduct of Food Safety Assessment of Foods Derived from Recombinant-DNA Animals. The assessment and/or the previous assessment considered: how AAS was developed; how the composition and nutritional quality of AAS compares to non-modified salmon; what the potential is for AAS to be toxic or cause allergic reactions; and the health status of AAS. AquaBounty Canada has provided data which demonstrates that AAS are as safe as traditional farmed salmon varieties used as food in Canada.

The Food Directorate has a legislated responsibility for pre-market assessment of novel foods and novel food ingredients as detailed in the Food and Drug Regulations (Division 28). Foods derived from AAS are considered novel foods under the following part of the definition of novel foods: "c) a food that is derived from a plant, animal or microorganism that has been genetically modified such that

  1. the plant, animal or microorganism exhibits characteristics that were not previously observed in that plant, animal or microorganism."

Product development

As part of the previous safety assessment (NF263) on the AAS filet, the petitioner had provided information describing the methods used to develop AAS and data that characterize the genetic modification which results in the rapid growth phenotype. AAS was developed by micro-injection of the opAFP-GHc2 construct into wild-type Atlantic salmon eggs. The transgene is comprised of the protein coding domain of a growth hormone gene (GH) from Chinook salmon (Oncorhynchus tshawytscha) and the regulatory sequences (opAFP) of an antifreeze protein (AFP) gene from ocean pout (Macrozoarces americanus).

There have been no changes to the development of the product. Based on this, Health Canada is of the opinion that the previous assessment (NF-263) still applies and therefore has no safety concerns regarding the head-on-gutted form of AAS from a molecular biology perspective.

Characterization of the modified animal

As stated above there have been no changes to the development of the product, therefore the previous safety assessment is applicable and there was no need to conduct another characterization of the AAS. The decision document for the previous safety assessment can be found here and contains details on the characterization of AAS.

Product information

Once more, there have been no changes to the development of the product, therefore the previous safety assessment is applicable and product information can be found here in the previous decision document.

Dietary exposure

AAS represent an alternative to other farmed Atlantic salmon in the marketplace. Dietary exposure will be relying on existing seafood preferences. The consumption of AAS is expected to represent a small proportion of the Atlantic salmon already being consumed by the Canadian public. AAS is not expected to affect the total consumption of salmon by Canadian consumers.

Nutrition

The petitioner conducted a study to compare the nutritional composition of three genetic groups of fish for human consumption: AAS (triploid), TG (diploid E0-1α carrier) and NTG (diploid) Head-on-Gutted (HOG). A total of 30 fish samples (ten from each group) were analysed for proximates, 38 fatty acids, 18 amino acids, nine minerals and four vitamins.

There were no statistical differences (P>0.05) between weight, head weight, HOG weight and fillet weight for the three genetic groups. AAS and TG were significantly (7.7%) longer than NTG animals (AAS, P < 0.05; TG, P < 0.001). Gonadal weight (GW) varied significantly among genetic groups, with AAS fish having a significantly lower GW than either TG (P < 0.001) or NTG (P < 0.05) fish. The differences in length and GW were expected and are in line with the modifications.

Genetic group effects on five proximate compositional traits (moisture, crude protein, total fat, total ash and total carbohydrate) both for head (H) and fillet (F) samples showed no statistically significant differences (P>0.05).

Genetic group effects on minerals (calcium, copper, iron, magnesium, manganese, phosphorus, potassium, sodium, and zinc) and vitamins B3 and B12 content showed no statistically significant differences (P>0.05).

The genetic groups AAS and TG exhibited a 30% reduction in vitamin D3 content compared to the NTG salmon (P< 0.05). This decrease in levels could be attributed to age differences between weight-matched transgenic and control fish. It is possible that the relatively younger transgenic fish required higher amounts of calcitriol (the biologically active form of vitamin D) for rapid cellular and skeletal growth, leading to the lower levels of vitamin D3.

In the context of dietary exposure, the total impact on the vitamin D3 would be about 6% lower intake, if it is assumed that AAS was the sole source of salmon consumed by an individual. The calculation is based on the assumption of consuming 150g of salmon per week, which is the average serving size in Canada. This small difference in the intake of fat-soluble vitamin can easily be offset by the consumption of a variety of foods as part of a balanced diet.

There were no statistically significant differences (P>0.05) for amino acids and fatty acids between the three genetic groups.

Based on the review of the provided information, which included new data on head samples, there are no nutritional safety concerns associated with the proposed use of the HOG product form of AAS.

Toxicology

Health Canada evaluated the toxicological safety of HOG AAS, which expresses the novel Chinook salmon growth hormone (GH-1). The primary edible tissue from HOG AAS will be the muscle and skin tissue from the fillet portion that is identical to the AAS fillet evaluated in the previous submission NF-263. The additional substantive portion of HOG AAS that could be consumed is the head-rack and this tissue was the main consideration for the toxicological review of the current submission. Based on data from the 2015 Canadian Community Health Survey (CCHS), the consumption of the salmon head is at minimum 33-fold lower than the consumption of salmon fillet. As such, it is anticipated that the head tissue of HOG AAS will likewise be infrequently consumed among the Canadian population.

The potential toxicological hazards from consumption of HOG AAS, irrespective of the tissue or portion of salmon consumed, relate to dietary exposures to the novel Chinook salmon GH-1, its associated target hormone insulin-like growth factor 1 (IGF-1), and other hormones linked to the somatotropic axis [estradiol, testosterone, 11-ketotestosterone (11-KT), triiodothyronine (T3) and thyroxine (T4)]. These potential toxicological hazards are identical to those identified for AAS fillet (NF-263).

The petitioner conducted a hormonal composition analysis to quantify the concentrations of each hormone in the head tissue from HOG AAS and non-transgenic (NTG) salmon using liquid chromatography with tandem mass spectrometry (LC-MS/MS) methods. However, the hormones were not detected above their respective limits of quantitation (LOQ) and it was not possible to compare hormonal levels between HOG AAS and NTG salmon. This is in contrast to the radioimmunoassay (RIA) method used in the hormonal composition analysis for NF-263, in which quantifiable levels of hormones (except GH) were detected and it was shown that there were no meaningful differences in hormone levels from the fillet of AAS and NTG salmon. As such, the RIA method produced acceptable results to support the previous notification of AAS fillet in NF-263. According to the petitioner, the method was changed (from RIA to LC-MS/MS) as RIA is not widely available through contract labs and that the petitioner also sought a method that could simultaneously quantify allergens.

Given that equivalency in hormonal levels in head tissue of HOG AAS and NTG salmon could not be demonstrated using the LC-MS/MS method for the current submission, the toxicological assessment for HOG AAS relied on: general safety characteristics of these dietary hormones (e.g., history of safe exposure via the diet, digestibility and inactivation of hormones, and poor oral bioavailability); and determination of dietary exposure margins for each hormone under the worst-case assumption (i.e., the hormones will be present in the head tissue of HOG AAS at the LOQ of the LC-MS/MS method) in relation to established Joint FAO/WHO Expert Committee on Food Additives (JECFA) acceptable daily intake (ADI) values and/or endogenous systemic hormone levels in humans.

Chinook salmon is a commonly consumed species of salmon in North America and incidental exposure to GH-1 from Chinook salmon has occurred in fish consumers without reports of toxicity. Likewise, all other hormones mentioned above are also naturally present in salmon, meats, dairy, and other animal-based foods that are commonly consumed in North America, suggesting that these hormones have a history of safe consumption.

The scientific literatureFootnote 1 indicates that protein hormones such as GH and IGF-1 from various animal species have very poor oral bioavailability in mammals (i.e., ingested GH or IGF-1 would likely be digested and not be absorbed as an intact peptide in the gastrointestinal tract). Additionally, foods prepared from HOG AAS, particularly those involving fish head, are cooked at temperatures that are sufficient to denature GHs and IGF-1.Footnote 2 The denaturation of these protein hormones will render them non-functional and greatly diminish their ability to activate target receptors in order to induce a physiological effect.

The dietary exposures to total GH (including the transgenic Chinook salmon GH-1) and IGF-1 from consumption of the head tissue from HOG AAS are anticipated to be only a minor fraction of the total endogenous amounts of each hormone produced daily in humans. Assuming the worst-case scenario (i.e., the hormones will be present at the LOQ of the LC-MS/MS method), the dietary exposures to total GH and IGF-1 from the head tissue from HOG AAS were estimated to be ≥2400-fold and ≥125-fold below the endogenous levels of GH and IGF-1, respectively, in the subpopulation potentially most sensitive to perturbations of the GH/IGF-1 axis (i.e., teenage boys).

Various cross-species receptor binding studiesFootnote 3 show that non-primate GH peptides are unable to bind to human GH receptors with sufficient affinity to initiate a cellular response. As such, due to this species specificity, any minute amounts of Chinook salmon GH-1 that could be absorbed following oral ingestion are not expected to elicit a somatotropic response.

Steroid hormones such as estradiol and testosterone are susceptible to inactivation in the gastrointestinal tract and liver. According to published studiesFootnote 4 in the scientific literature, 90% of ingested steroid hormones are inactivated by the first-pass effect of the liver and the oral bioavailability of estradiol and testosterone is ≤5%.

In 2000, JECFA assessed the safety of estradiol and testosterone for use as veterinary drugs administered to food-producing animals. The Committee established ADIs of 50 ng/kg bw per day for estradiol and 2000 ng/kg bw per day for testosterone based on human epidemiological data. Assuming that both estradiol and testosterone are present at their respective LOQ levels in the head tissue of HOG AAS, the dietary exposures to estradiol or testosterone are not expected to be greater than 0.51% and 0.013% of the ADI of estradiol and testosterone, respectively, in the 95th percentile of fish consumers.

No specific information related to the oral bioavailability of 11-KT, T3, or T4 hormones was identified. However, assuming that all three hormones are present at their respective LOQ levels in the head tissue of HOG AAS, the dietary exposures to these hormones will be comparable to or lower than that from the more commonly consumed fillet meat evaluated previously in NF-263, considering the substantially lower consumption of salmon heads than the fillet. Additionally, in the 95th percentile of fish consumers, the anticipated dietary exposures to the thyroid hormones T3 and T4 from HOG AAS head were determined to be ≥75-fold below human systemic levels, while 11-KT was ≥98-fold below human systemic levels, suggesting human endogenous hormone levels far exceed those that could potentially be ingested from consumption of HOG AAS

Based on available data, the overall weight-of-evidence suggests that HOG AAS is not expected to pose any additional toxicological safety concerns for consumers compared to conventional salmon.

Allergenicity

Health Canada assessed the potential allergenicity of HOG AAS, including the novel Chinook salmon GH-1 protein expressed by the genetically modified salmon. In support of the allergenic safety of HOG AAS, the petitioner provided results of an in silico allergen sequence homology search of the Chinook salmon GH-1 protein and a compositional analysis of major salmon allergens in the head and fillet tissues of HOG AAS and NTG salmon. Additional information consisting of a radioallergosorbent test (RAST)-inhibition (RI) assay to measure allergen potency was available from the previous submission NF-263, and was considered relevant to further support the allergenic safety of HOG AAS.

The petitioner conducted an amino acid sequence search using the AllergenOnline databaseFootnote 5 to identify potential sequence homology between Chinook salmon GH-1 protein and known allergens. Searches included a full FASTA alignment, a sliding window of 80 amino acid stretches, and a search for 8 contiguous amino acids. No matches were identified in any of the alignment or homology searches. The results of bioinformatics analysis suggest that the Chinook salmon GH-1 is not expected to be cross reactive with known food allergens.

Chinook salmon GH-1 is likely to be readily digested following consumption and it is not expected to be present intact in the body to elicit an allergenic reaction. Routine consumption of GH-1 from Chinook salmon has not been associated with any allergenicity.

Health Canada recognizes seafood, including finfish such as salmon, as a priority food allergen. The petitioner conducted a compositional analysis study to quantify the levels of the following three major salmon allergens in the head and fillet tissues of HOG AAS and NTG salmon: aldolase, enolase, and β-parvalbumin. None of these allergens were expressed at elevated levels in HOG AAS compared to NTG salmon.

In the previous submission for NF-263, a RI assay to measure allergen potency using allergic human blood sera did not identify any biologically or clinically significant allergenic response between AAS and NTG control.

The information provided by the petitioner was reviewed and does not have any concerns related to potential allergenicity. While the product does contain proteins that could trigger allergic reactions in consumers who are allergic to salmon, these proteins are present at levels similar or lower than the levels found in NTG fish. Consumers with allergy to salmon are expected to avoid consuming this product.

Based on available data, the overall weight-of-evidence suggests that HOG AAS is not expected to pose any additional allergenic safety concerns for consumers compared to conventional salmon.

Animal health

As stated above there have been no changes to the development of the product, therefore the previous animal health assessment is applicable and there was no need to conduct another animal health assessment of AAS. The decision document for the previous safety assessment can be found here and contains details on the animal health of AAS.

Conclusion

Health Canada's review of the information presented in support of the food use of HOG AAS does not raise concerns related to food safety. Health Canada is of the opinion that the HOG form of AAS are as safe and nutritious as farmed Atlantic salmon currently available on the market.

Health Canada's opinion deals only with the food use of HOG AAS.

This Novel Food Information document has been prepared to summarize the opinion regarding the subject product provided by the Food Directorate, Health Products and Food Branch, Health Canada. This opinion is based upon the comprehensive review of information submitted by the petitioner according to the Guidelines for the Safety Assessment of Novel Foods.

For further information, please contact:

Novel Foods Section
Food and Nutrition Directorate
Health Products and Food Branch
Health Canada, PL2204A1
251 Frederick Banting Driveway
Ottawa, Ontario K1A 0K9
bmh-bdm@hc-sc.gc.ca

References:

Footnote 1

Forsberg G, et al. (1990) Biochem J.; 271`(2):357-63.
Kimura T et al. (1997). J Pharmacol Exp Ther.; 283(2):611-8.
Xian CJ et al. (1995). J Endocrinol.;146(2):215-25.
JECFA. 2000. Porcine somatotropin (WHO Food Additives Series 43). 52nd Meeting.
Parmentier J, et al. (2014). J Pharm Sci.;103(12):3985-93.

Return to footnote 1 referrer

Footnote 2

Collier RJ et al. (1991). J Dairy Sci.;74(9):2905-11.
Le Breton MH et al. (2010). Anal Chim Acta.; 5;672(1-2):45-9.

Return to footnote 2 referrer

Footnote 3

Juskevich JC (1990). Science; 249(4971):875-84.
Souza SC et al. (1995). Proc Natl Acad Sci USA; 92(4):959-63.
Liu JC et al. (2001). Mol Biol Evol.; 18(6):945-53.

Return to footnote 3 referrer

Footnote 4

Hartmann S, (1998). Food Chemistry; 62(1):7-20.
JECFA. 2000. Estradiol-17ß, Progesterone, and Testosterone (WHO Food Additives Series 43). 52nd Meeting.

Return to footnote 4 referrer

Footnote 5

http://www.allergenonline.org/ (Version 21; February 2021).

Return to footnote 5 referrer

Page details

Date modified: