The balance of n-6 and n-3 fatty acids in canine, feline, and equine nutrition: exploring sources and the significance of alpha-linolenic acid

Abstract

Both n-6 and n-3 fatty acids (FA) have numerous significant physiological roles for mammals. The interplay between these families of FA is of interest in companion animal nutrition due to the influence of the n-6:n-3 FA ratio on the modulation of the inflammatory response in disease management and treatment. As both human and animal diets have shifted to greater consumption of vegetable oils rich in n-6 FA, the supplementation of n-3 FA to canine, feline, and equine diets has been advocated for. Although fish oils are commonly added to supply the long-chain n-3 FA eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), a heavy reliance on this ingredient by the human, pet food, and equine supplement industries is not environmentally sustainable. Instead, sustainable sourcing of plant-based oils rich in n-3 α-linolenic acid (ALA), such as flaxseed and camelina oils, emerges as a viable option to support an optimal n-6:n-3 FA ratio. Moreover, ALA may offer health benefits that extend beyond its role as a precursor for endogenous EPA and DHA production. The following review underlines the metabolism and recommendations of n-6 and n-3 FA for dogs, cats, and horses and the ratio between them in promoting optimal health and inflammation management. Additionally, insights into both marine and plant-based n-3 FA sources will be discussed, along with the commercial practicality of using plant oils rich in ALA for the provision of n-3 FA to companion animals. Lay Summary In the realm of companion animal nutrition, the balance between the n-6 and n-3 fatty acids (FA) is important. The shared metabolic pathway of these two FA families and the respective signaling molecules produced have implications for the well-being of companion animals such as dogs, cats, and even horses. The n-6:n-3 FA ratio of the diet can directly influence inflammatory responses, disease management, and overall health. Given the prevalent use of n-6 FA-rich vegetable oils in both human and animal diets, there is a growing need to supplement these animals’ diets with n-3 FA. While fish oils containing the long-chain n-3 FA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been the conventional choice, their overreliance is environmentally unsustainable. Plant-based oils abundant in the n-3 FA α-linolenic acid (ALA) such as flaxseed and camelina oils should be considered, especially given the health benefits of ALA that extend beyond its role as a precursor to EPA and DHA. This review examines the importance of n-3 FA and the n-6:n-3 FA ratio in companion animal diets on animal health while discussing environmentally sustainable alternatives to fish oil to supplement n-3 FA.