This blog is written by Guest Author, Jennifer Adolphe, PhD, RD, Senior Nutritionist at Petcurean (http://www.petcurean.com/).

There has been a fundamental change in how consumers view their pets with the interest in healthy and natural foods finding a broader, more receptive audience. Flaxseed can play an important role in the formulation of pet products that are of both higher quality and healthier.

Flaxseed provides a unique mix of fatty acids and contains both essential polyunsaturated fatty acids, omega-3 α-linolenic acid (C18:3n-3; ALA) and omega-6 linoleic acid (C18:2n-6; LA). ALA is a precursor for the long-chain omega-3 fatty acids, docosapentaenoic acid (C20:4n-3; DPA) and eicosapentaenoic acid (C20:5n-3; EPA), and to some extent is also converted to docosahexaenoic acid (C22:6n-3; DHA), fatty acids that naturally occur in fish and fish oil. Similarly, LA is converted to long-chain omega-6 fatty acids, in particular arachidonic acid (C20:4n-6; AA), by the same series of enzymes that metabolize ALA.

The National Research Council (NRC),¹ and more recently the Association of American Feed Control Officials (AAFCO),² have established recommendations of omega-3 fatty acids for dogs and cats (Tables 1 and 2). AAFCO is a voluntary membership association of local, state and federal agencies that regulate the sale and distribution of animal feed, including pet food. The AAFCO Official Publication includes minimum, and some maximum, nutrient requirements with which ‘complete and balanced’ pet foods sold in the United States must comply. Thus, changes in the nutrient profiles in the AAFCO Official Publication has a significant impact on pet food formulation. The addition of omega-3 fatty acid requirements to the AAFCO Official Publication for the first time in 2016 means that pet food manufacturers will be reviewing their formulations to ensure compliance, thereby paving the way for increased demand for omega-3 rich ingredients such as flaxseed.

Table 1. National Research Council omega 3 fatty acid requirements for dogs and cats¹

DM, dry matter; ME, metabolizable energy; EPA, eicosapentaenoic acid; DHA, docosapentaenoic acid

^aValues calculated assuming a dietary energy density of 4,000 kcal ME/kg.

^bRequirement for α-linolenic acid varies depending upon linoleic acid content of the diet. The ratio of linoleic acid to α-linolenic acid should be between 2.6 and 26.

^cEPA should not exceed 60% of the total amount.

^d50-60% of the total amount should be EPA, and 40-50% should be DHA.

^eIncludes DHA only. It is advised that EPA is included but not exceed 20% of the total EPA + DHA amount.

Table 2. Association of American Feed Control Officials omega-3 fatty acid requirements for dogs and cats²

DM, dry matter; EPA, eicosapentaenoic acid; DHA, docosapentaenoic acid

^aBased on dietary energy density of 4,000 kcal ME/kg.

The metabolism of omega-3 fatty acids depends on other nutrients, particularly omega-6 fatty acids due to competition for the same conversion enzymes.³ Higher amounts of dietary ALA, as well as decreased LA, result in increased conversion of ALA to EPA, DPA and DHA.^3,4 Eicosanoids are hormone-like substances that affect inflammation. They are produced from both ALA (less inflammatory) and LA (mostly pro-inflammatory). Diets that are high in LA and low in ALA skew eicosanoid production towards a more inflammatory profile. Flaxseed can help to improve dietary omega-6 to omega-3 ratios since it contains more than three times as much omega-3 as omega-6 fatty acids.

Studies have found that DPA is the main ALA metabolite in cell membranes of many animals, and as such it may be an important reservoir for either EPA or DHA synthesis.⁵ Rapid accumulation of EPA, but not DHA, was reported in the serum of dogs when a 3% whole ground flaxseed supplement was added to a moderately high LA-containing diet (7.3% of energy as LA).⁵ In another study, when dogs were fed a diet containing flaxseed providing 10.1% of total fatty acids from ALA, the plasma levels of EPA and DPA increased quickly, achieving a steady state after approximately 28 days, though DHA levels did not change.⁶ However, DPA may be transported to other tissues such as the brain and retina for DHA synthesis for local use within these tissues, especially when dietary sources of DHA are scarce.⁶ In fact, dogs have been shown to be able to convert DPA to DHA in the retina and presumably other nervous system tissues.⁷ Cats also are able to synthesize long-chain omega-3s in the liver and brain when dietary EPA, DPA, and DHA are not provided.⁸

DHA is a critically important omega-3 fatty acid during gestation and growth, particularly for brain and retina development. Dietary pre-formed DHA is recommended for pregnant or lactating dogs and cats as well as for puppies after weaning, though ALA from flaxseed also can help to support adequate DHA levels in puppies.⁹ Newborn puppies have been shown to preferentially synthesize DHA from ALA, suggesting that the enzymes involved in ALA to DHA metabolism are more active early in life when demand for DHA is high.⁹ Flaxseed can be used to increase ALA in mothers’ milk in both dogs and cats in order for this essential fatty acid to be transferred to their offspring.¹⁰

Therapeutic pet diets high in omega-3 fatty acids are available for managing various diseases, particularly those with an inflammatory component, including cancer, skin disorders, cardiovascular disease, renal disease, gastrointestinal disorders and orthopedic disease.¹¹ However, awareness regarding the importance of omega-3 fatty acids to overall pet health has led to higher inclusion levels in many adult maintenance diets as well.

Canine atopic dermatitis is a common skin disease with treatments including drug therapy and fatty acid supplementation.¹² In a study that provided a placebo (mineral oil), an EPA (50-85 mg/kg) plus DHA (35-55 mg/kg) supplement, or flaxseed oil capsules (with ALA of 200-335 mg/kg) to dogs with non-seasonal atopic dermatitis, approximately half of the dogs in the two fatty acid treatment groups improved by more than 50%. Complete remission was achieved in 10-20% of dogs.¹² In cats, flaxseed oil also may be useful in controlling inflammatory responses, including allergic reactions. The inflammatory response of skin cells to histamine was found to decrease by 50% and 20-40% during the initial 45 min post-injection period in cats fed flaxseed oil and in those fed fish oil, respectively, compared to control.¹³

Osteoarthritis involves an inflammatory component that may be influenced by nutritional supplementation, particularly omega-3 fatty acids. In dogs with osteoarthritis fed a test diet containing omega-3 fatty acids, owners reported significantly improved ability of their pets to rise from a resting position and play at 6 weeks, as well as an improved ability to walk at 12 and 24 weeks, compared with control dogs.¹⁹ The control diet consisted of a commercial food. The test diets (dry and canned formulas) contained a 31-fold increase in the amount of total omega-3 fatty acids (ALA, EPA, DHA) and a 34-fold decrease in the omega-6 to omega-3 ratio compared with the control food.¹⁴ The dry and canned test foods contained flaxseed, flaxseed oil and/or fish oil, providing 2.84% and 2.23% ALA, respectively.¹⁴

Pets are living longer and subsequently developing age-related problems similar to their human owners. Consistent with their own ways of staying healthier by eating better, pet owners are looking for similar ingredients to promote health and wellness in their animals. Flaxseed offers a sustainable, plant-based omega-3 fatty acid option for pet foods.

References

1. National Research Council. Nutrient Requirements of Dogs and Cats. Washington, D.C.: The National Academies Press, 2006.
2. Association of American Feed Control Officials. 2016 Official Publication. Oxford, IN: Association of American Food Control Officials Inc., 2016.
3. Brenna JT, et al. Prostaglandins Leukot Essent Fatty Acids 2009;80:85-91.
4. Goyens PL, et al. Am J Clin Nutr 2006;84:44-53.
5. Dunbar BL, et al. Lipids 2010;45:1-10.
6. Bauer JE, et al. J Nutr 1998;128:2641s-2644s.
7. Alvarez RA, et al. Invest Ophthalmol Vis Sci 1994;35:402-408.
8. Pawlosky R, et al. J Lipid Res 1994;35:2032-2040.
9. Heinemann KM, et al. J Nutr 2005;135:1960-1966.
10. Bauer JE, et al. J Nutr 2004;134:2035s-2038s.
11. Lenox CE, et al. J Vet Intern Med 2013;27:217-226.
12. Mueller RS, et al. J Small Anim Pract 2004;45:293-297.
13. Park HJ, et al. Vet Immunol Immunopathol 2011;141:301-306.
14. Roush JK, et al. J Am Vet Med Assoc 2010;236:59-66.

Dr. Jennifer Adolphe graduated with her Ph.D. in companion animal nutrition from the University of Saskatchewan. She previously completed a master’s degree in human nutrition and is a registered dietitian with the College of Dietitians of British Columbia. Her Ph.D. research examined the effect of carbohydrates on metabolic and cardiovascular health in lean and obese dogs. Adolphe is the recipient of more than 20 awards and scholarships for her academic work. Her work in the pet food industry has focused on product development and ingredient procurement. She is currently the senior nutritionist at Petcurean Pet Nutrition, a Canadian, family-owned company committed to offering superior quality pet foods.