Dogs | Health & Nutrition | October 20, 2016

Krill: Superfood of the Sea

Dr. Jennifer Adolphe
By: Dr. Jennifer Adolphe
krill

Krill (Euphausia superba) are shrimp-like marine crustaceans. The term krill is from the Norwegian word for whale food.(1) Antarctic krill is a key food source for many ocean predators and has recently become popular as a source of vital nutrients for both humans and pets.

Health & nutrition benefits of krill

Antarctic krill is a ‘superfood of the sea’ due to its rich content of long-chain omega-3 fatty acids and astaxanthin. In addition to its nutrient content, another important health benefit of krill is that it is low down on the food chain and eats algae as its food source, so krill is virtually free of pollutants and heavy metals.

Krill oil has become a popular dietary supplement for humans as an alternative source of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Krill meal is the form that has recently received regulatory approval for use in adult dog diets. It is produced from whole krill that has been dried and ground. Krill meal may mistakenly be considered a rendered pet food ingredient. The term meal is often associated with rendering because of the rendered meat meals that are a common ingredient in pet foods. However, meal simply refers to the grinding of an ingredient, not the rendering process. Krill meal is not produced by rendering as it is cooked for a much shorter time period and at a lower temperature than rendering.

Omega-3 fatty acids

The oil in krill is a particularly rich source of the omega-3 fatty acids EPA and DHA. Most fats and oils are higher in omega-6 than omega-3 fatty acids, but it is important for pets to receive a balance of both, which can be achieved with the inclusion of krill in dog diets. EPA and DHA are metabolized in the body into substances that affect inflammation, with omega-3s considered less inflammatory than omega-6s. The National Research Council (NRC) recommends a ratio of 2.6:1 to 26:1 omega-6 to omega-3.(2) The Association of American Feed Control Officials have set a maximum omega-6 to omega-3 ratio of 30:1.3 For comparison, the recommended intake for humans is 5:1 to 10:1 omega-6 to omega-3.(4)

Phospholipids are the building blocks of cell membranes. The omega-3 fatty acids in krill oil are unique because they are in the form of phospholipids, rather than the triglyceride form that is found in fish oil. The phospholipid form may enhance the delivery of EPA and DHA to tissues, particularly in the heart, liver and brain.(5)

Astaxanthin

Astaxanthin is a naturally-occurring pinkish-orange coloured carotenoid in krill that possesses antioxidant and anti-inflammatory properties. In humans, astaxanthin has been shown to improve liver, heart, eye, joint and prostate health.(6) In addition, the omega-3 fatty acids and astaxanthin in krill may work synergistically to prevent loss of cognitive function.(6) Astaxanthin also acts as a natural preservative to maintain the freshness and quality of krill meal.

Krill sustainability

Concerns about the sustainability of wild fish stocks have resulted in the need to find alternative dietary sources of marine omega-3 fatty acids. The krill fishery in Antarctica is managed by the international Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). This organization follows an ecosystem-based management approach that permits krill harvesting as long as it is carried out in a sustainable manner and considers the effects on the broader ecosystem. Currently, the annual krill harvest produces about 300,000 tonnes, the precautionary catch limit is set at 5.6 million tonnes, and the total estimated krill biomass is 60.3 million tonnes( 1). There has been no observed impact of the krill fishery on the ocean ecosystem around Antarctica due to the small annual harvest compared to the large biomass and the management regime set by CCAMLR (1).

Obtaining Marine Stewardship Council (MSC) certification is a further step that krill fisheries can take to demonstrate their commitment to sustainable krill harvesting. MSC is a certification program that requires fisheries and manufacturers to have independent third-party audits performed to guarantee seafood is harvested using sustainable methods and is traceable throughout the supply chain. Using an advanced harvesting method that prevents the capture of unwanted species prevents negative impacts on the surrounding ecosystem. In addition, sophisticated equipment on the fishing vessel allows for full traceability of every batch, right down to the harvest date, time and GPS coordinates.

Summary

Krill is a healthy, sustainable ingredient for dog foods. The key nutrients found in krill are the omega-3 fatty acids EPA, DHA as well as the antioxidant astaxanthin. Fortunately, due to an international commission that protects the krill biomass in Antarctica and responsible krill fisheries that obtain MSC certification, krill will be around for many future generations of both people and pets to receive its health benefits.

References

1. Siegal V, ed. Biology and ecology of Antarctic Krill. Switzerland: Springer International Publishing; 2016. Advances in Polar Ecology; No. 1.
2. National Research Council. Nutrient Requirements of Dogs and Cats. Washington, D.C.: The National Academies Press; 2006.
3. Association of American Feed Control Officials. 2016 Official Publication. Oxford, IN: Association of American Food Control Officials Inc.; 2016.
4. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, D.C.: National Academy Press; 2005.
5. Burri L, Johnsen L. Krill products: an overview of animal studies. Nutrients. 2015;7(5):3300-3321.
6. Barros MP, Poppe SC, Bondan EF. Neuroprotective properties of the marine carotenoid astaxanthin and omega-3 fatty acids, and perspectives for the natural combination of both in krill oil. Nutrients. 2014;6(3):1293-1317.