Fats: Including the Right Balance.

When I decided that I was adopting a greyhound I dove straight into the world of raw feeding. Personally, having celiac disease meant most kibble brands were off the table, and I didn’t want to try lots of grain-free foods when I have the time to make a raw-fed meal plan.

Other greyhound owners report several skin issues like coarse hair, baldness, and dandruff, so I focused my attention on getting Mr. Crowley’s fat intake balanced. By maintaining a near 1:1 ratio of omega-3 to omega-6 fatty acids in his diet, Crowley has a very soft coat that leaves many people leaving their hands on him – not that he minds.

Jt’s Mr. Crowley – March 2020. Look at the shine on this brindle boy! (Picture by K. Villalta)

Fat has many purposes in our diet and metabolism. It serves as an energy source that is easily stored and digested in comparison to protein and carbohydrates1. They are also considered part of the large macromolecule family of lipids. Lipids are found high concentration in many specialized tissues compared to protein, such as the myelin sheath of a nerve, and assist in retaining moisture throughout the body like skin and hair2. They are a fundamental component in all multicellular organism cells down to the cellular membrane. 

Figure 1A: A basic Fluid Mosaic Model, from Khan Academy (2016)
Figure 1B: Anatomy of the Phospholipid, from Khan Academy (2016)

Our cells are surrounded by a cellular membrane known as the phospholipid bilayer, and it contains lipids, proteins, and carbohydrates to maintain the fluidity and shape of each individual cell as shown in Fig. 1A3. This bilayer also allows for the passing of molecules through the cell. Furthermore, phospholipids are a single polar phosphate group head that is attracted to water (hydrophilic), and two or three fatty acids (FAs) attached to the head that doesn’t like water (hydrophobic) like in Fig. 1B3. This polarity in the lipid forces the polar head out and the FA tail inwards with other lipids to create a watertight barrier.

The FAs in lipids may be a straight chain with all single bonds between carbons, known as a saturated fatty acid4. The addition of a double or triple bond between carbons in the chain, however, changes a saturated FA into a kinked unsaturated FA like in Fig. 2. below4. The kink that’s made from the multiple-bond in all unsaturated FAs forces residing lipids over to create more space between, and therefore increases the flexibility of the overall cellular membrane. Both types are essential to include in diets and play different roles in the structural integrity of cellular membranes and organ tissues. Excellent examples of raw lipid sources of both saturated and unsaturated FAs include pork tongue, chicken thigh, and turkey. 

Figure 2: Difference between saturated and unsaturated fatty acids, from Khan Academy (2016).

Polyunsaturated (more than one multiple-bond) FAs (PUFAs) are essential FAs in your pet’s lipid metabolism, and the exact location of the first multiple-bond plays a large role in how your pet metabolizes them2. To address a dry coat and skin conditions, the unsaturated PUFAs to focus on are omega-3, 6, and 9. Omega-3’s are named for having the first double bond at the 3rd carbon in sequence, and omega-6’s are named for having a bond start at the 6th carbon4. Specialized tissues, like eye and brain tissue, require varying concentrations of omega-3s or omega-6s (such as kidneys) in their cellular membranes to perform their tasks, but most tissues simply work with the PUFAs that are digested2. Different animal fat sources are therefore added to a raw diet to provide a complete spectrum of PUFAs. 

The only PUFA that can’t be synthesized in a dog’s metabolism is one of the most abundant in mammalian cellular membranes – the omega-6 Linoleic Acid4. It is the precursor to the intermediate FAs omega-3 alpha-linolenic (ALA) and omega-6 gamma-linolenic acid (GLA)4. Olive and soy oils are abundant in linoleic acid, but for a raw diet chicken and pork are both sources of linoleic and gamma-linoleic acid1. The AAFCO recommends 2.8g of linoleic acid per 1000kcal fed for dog maintenance, and as regular ground pork contains 1.67g of linoleic acid per 100g meeting the minimum requirement is simple. Without proper supplementation of linoleic acid your pet may experience nerve damage and coordination loss. 

Grocery store meat, including steak, is often high in omega-6 fatty acids. Picture from Victor Haneck (2020).

The meat found in grocery stores (beef, chicken, and pork) is usually much higher in omega-6s to omega-3s, and many diets would benefit from supplementation for the omega-3s ALA, EPA, and DHA requirements. As the majority of kibble is based on chicken or pork protein, the amount of omega-6 in popular pet food brands is also higher than omega-3. While one study5 noted by the National Research Council suggests no ill-effects on dogs fed a 5:1 ratio of omega-6 to omega-3, further studies show that there is a reason to balance these PUFAs close to 1.

For example, ALA is an essential omega-3 that is often supplemented in your pet’s diet due to it’s poor conversion from linoleic acid, and it is necessary to produce EPA in small quantities3. Cats are not able to convert ALA to EPA at all, so additional EPA supplementation is needed for them2. Dogs and cats are very poor convertors of ALA to DHA, and therefore it is another omega-3 fatty acid that must be supplemented in the diet3. Fish like mackerel and salmon, or marine algae, are excellent sources of DHA and the other omega-3s4

Fresh salmon fillet is a great source of ALA, EPA, and DHA omega-3 fatty acids. Picture from Viktor Haneck (2020).

The benefits of adding omega-3s are found in your pet’s hair, skin, and even their immune system can be seen in several concurring studies. A study submitted in 2013 to the Veterinary Journal of Medicine by S. Cerrato, et al, describes distinct thickening of epithelial layers of cells provided excess omega-3 FAs in comparison with the control. The authors also found that the addition of omega-3 oil supported healthier epithelial layers and cell proliferation, increasing the amount of water the skin retained8. The addition of omega-3 allows for better water retention in the skin, and you can visibly see this effect with the extra shine found on your animal’s fur and softness of their skin. 

Adding omega-3s may also help aid in fighting cancer through a modified inflammatory response. A mammary cancer study performed in 2019 by Costa-Santos, K., et al, didn’t show a prolonged life expectancy for dogs with mammary cancer after omega-3 supplementation was added, but it did highlight the growing evidence of anti-inflammatory properties the FAs may possess. The dogs fed a pressed omega-3 oil supplement in their diet over a 90-day trial experienced a decrease in the specific pro-inflammatory marker VLDL-C (very low-density lipoprotein type C) – supporting a theory that omega-3s reduce inflammation through metabolism9. The Nutrient Requirements of Dogs and Cats (2006) by the National Research Council also supports inflammatory reduction with earlier studies showing anti-inflammatory markers present in test subjects given omega-3 supplementation for arthritis.

Even if you believe your pet’s coat doesn’t need extra shine or a softer coat there are other beneficial reasons to add some omega-3 to your pet’s diet such as better nerve, cognitive function and reducing inflammation. Adding an additional source of omega-3 for your pet supports overall cellular functions and is clinically proven to reduce inflammation.

I hope I’ve shed a bit of light on the importance of fat overall in a diet down to the cellular level and an understanding of the different types of polyunsaturated fatty acids you and your pet’s body needs to perform its daily functions.

Next post will be on how to incorporate fat into your pet’s diet, specifically omega-3 supplementation!


References
  1. Case, L. P., et al. (2010). Canine and Feline Nutrition – E-Book: A Resource for Companion Animal Professionals, Elsevier Health Sciences: USA. ISBN: 9780323071475
  2. Washabau, R. J., and Day, M. J. (2012). Canine and Feline Gastroenterology – E-Book, Elsevier Health Sciences: USA. ISBN: 9781437703023.
  3. Borrell, J.H., et al. (2016). Membrane Protein – Lipid Interactions: Physics and Chemistry in the Bilayer, Springer: New York. ISBN: 9783319302775.
  4. Ahmad, M. U. (2017). Fatty Acids: Chemistry, Synthesis, and Applications, Elsevir: USA. ISBN: 9780128095447.
  5. NRC, et al. (2006). Nutrient Requirements of Dogs and Cats, National Academies Press: USA. ISBN: 9780309086288
  6. AAFCO. (2014). AAFCO Dog and Cat Food Nutrient Profiles: AAFCO METHODS FOR SUBSTANTIATING NUTRITIONAL ADEQUACY OF DOG AND CAT FOODS. Web. Retrieved March 29th 2020 from https://www.aafco.org/Portals/0/SiteContent/Regulatory/Committees/Pet-Food/Reports/Pet_Food_Report_2013_Midyear-Proposed_Revisions_to_AAFCO_Nutrient_Profiles.pdf
  7. SR Legacy. (2019). Pork, fresh, ground, raw. USDA FoodData Central. Web. Retreived from https://fdc.nal.usda.gov/fdc-app.html#/food-details/167902/nutrients
  8. Cerrato, S., et al. (2013). Effects of Essential Oils and Polyunsaturated Fatty Acids on Canine Skin Equivalents: Skin Lipid Assessment and Morphological Evaluation, Journal of Veterinary Medicine. Volume 2013. http://dx.doi.org/10.1155/2013/231526
  9. Costa, S., et al. (2019). Lipid and metabolic profiles in female dogs with mammary carcinoma receiving dietary fish oil supplementation. BMC Veterinary Research, 15(401). https://doi.org/10.1186/s12917-019-2151-y

One Comment on “Fats: Including the Right Balance.

  1. Pingback: Incorporating Omega-3s in Your Pet’s Diet – In It for the Long Dog

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