Omega 3 – part 1

Essential nutrients are chemicals that need to be provided in the diet, as body cannot synthetize them from other, simpler molecules.

Essential fatty acids are required for normal function of the organisms, i.e. their role far exceeds the plain function of fat as a source of energy. Their effect starts at a cellular level, and so impacts on many systems and organ function, including inflammation, cell growth, nervous system and many more.

Polyunsaturated fatty acids (PUFAs) – are fatty acids that contain more than one double bond between oxygen and carbon in their chemical constitution.

Omega 3, 6 and 9 – are a sub-group of PUFAs (there are a couple more groups ), differentiated by the location of their first double-bond, counted from the end. So, Omega 3 has it closest to the end of the molecule, 6 has it a bit further in the molecule and 9 yet further.

EPA and DHA – docosahexaenic acid (DHA) are long (20 and 22 carbon molecules in the chain, for EPA and DHA respectively) Omega 3 PUFAs (5 double bonds for EPA, 6 for DHA), contained in fish oil. Particularly beneficial for maintaining healthy body systems.

In the strict division, there are only two truly essential acids: Omega 6 linoleic acid (LA) and Omega 3 linolenic acid (ALA). They can be converted to other fatty acids but in reality, conversion rates for most are quite limited, hence a need for provision of these acids in diet (and why in some non-scientific publications, other fatty acids are also termed as essential). Conversion rates in humans have been estimated at <10% [1], in dogs the conversion from LA (Omega6) and ALA (Omega3) has been detected for EPA but not for DHA [2].

Both Omega3 and Omega6 are needed in the normal functioning of the organism, but, they actually compete with each other in certain physiological processes. As both have important roles, the ratio of Omega 3 to Omega 6 (for both, total amounts provided in diet and synthesized de novo) should be approximately equal (ratio 1:1), unfortunately, modern diets have much higher ratios, e.g. 15:1 in humans [3]. This high ratio is supposedly associated with an increase in inflammatory and autoimmune diseases, cancer and cardiovascular disease [3]. I don’t think there is a study evaluating Omega 6:3 ratio in modern dog diets, but as most of the meat produced worldwide nowadays is intensively bred (i.e. housed and fed on concentrates, rather than fresh grass, or even silage) and there is research showing a depletion of Omega 3’s in meat from animals raised in such systems [4–6], it follows that the same shift towards Omega 6 will be observed.

While the ratio has been historically quite a common way to determine the fatty acid profile of a diet, nowadays it is not as attractive [7]. We know now, that actual content of EPA, DHA and ALA is very important, arguably more important than the overall content of Omega 3. Diets with the same Omega 6:3 ratio can have vastly different fatty acid profiles, and different function, caused by different health benefits of EPA/DHA, far outweighing the benefits of ALA. I will prepare another blog which will list the health benefits of EPA/DHA, together with dosages recommended with supplementation.

For now, let’s concentrate on the daily requirements for those two Omega fatty acids in a normal, healthy dog.

FEDIAF (European Pet Food Industry) has no minimum or maximum recommended dose for adult dogs, but does list a minimum of 0.13g per 1000kcal ME for growth and reproduction stages. NRC lists the recommended allowance of 0.11g per 1000kcal ME, with a safe upper dosage of combined EPA+DHA at 2,800mg/1,000kcal, or 370mg per (kg od body weight)0.75[8].

Given its biological function, it does seem a little weird that there are no minimum requirements for those two components… But we can calculate it ourselves!

As discussed in the previous blog on basic terms in energy requirements, we can approximate the minimum amount from the recommended allowance and the RER.

Table below shows the recommended EPA+DHA for a RER level as the minimum, and the maximum both from the energy and body weight.

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  • BW – body weight in kg
  • RER – resting energy requirement
  • kcal – energy requirement in calories, calculated assuming moderate activity
  • min EPA+DHA = (RER*0.11)/1000
  • max EPA+DHA from kcal = (kcal/moderate activity *2.8)/1000
  • max EPA+DHA from MW = (MW*0.37)

In the above table, I calculated the minimum and maximum dosages of EPA+DHA in grams. There is a slight difference between the maximum amounts calculated using kcal and MW – presumably this is because I have used a moderate activity level. Calculating it for active, growing or nursing animals with higher energy requirements would result in a considerably higher number.

Next time, I will list the contents of various fatty acids in different meat products. Following this, I will list the known benefits of supplementing with EPA+DHA and compare dosages used to the above, “safe” doses.

 

 

 

  1. Brenna JT, Salem N, Sinclair AJ, Cunnane SC, International Society for the Study of Fatty Acids and Lipids, ISSFAL. alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins Leukot Essent Fatty Acids. 2009;80:85–91.
  2. Bauer JE, Dunbar BL, Bigley KE. Dietary Flaxseed in Dogs Results in Differential Transport and Metabolism of (n-3) Polyunsaturated Fatty Acids. J Nutr. 1998;128:2641S-2644S.
  3. Simopoulos AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother Biomedecine Pharmacother. 2002;56:365–79.
  4. Daley CA, Abbott A, Doyle PS, Nader GA, Larson S. A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutr J. 2010;9:10.
  5. Moreau M, Troncy E, Castillo JRE del, Bédard C, Gauvin D, Lussier B. Effects of feeding a high omega-3 fatty acids diet in dogs with naturally occurring osteoarthritis. J Anim Physiol Anim Nutr. 2013;97:830–7.
  6. Ponnampalam E, Mann N, Sinclair A. Effect of feeding systems on omega-3 fatty acids, conjugated linoleic acid and trans fatty acids in Australian beef cuts: potential impact on humnan health. Asia Pac J Clin Nutr. 2006;15:21–9.
  7. Harris WS. The omega-6/omega-3 ratio and cardiovascular disease risk: Uses and abuses. Curr Atheroscler Rep. 2006;8:453–9.
  8. National Research Council, Division on Earth and Life Studies, Board on Agriculture and Natural Resources, Committee on Animal Nutrition, Subcommittee on Dog and Cat Nutrition. Nutrient Requirements of Dogs and Cats. National Academies Press; 2006.