• Search

  • Omega 3 And 6 Essential Fatty Acids – The Good, The Bad And The Harmful

    Omega 3 And 6 Essential Fatty Acids – The Good, The Bad And The Harmful

    Just like with humans, some natural supplements are beneficial to our pets and can boost the immune system, reduce the occurrence and impact of disease, and help keep your pet in optimum health. Omega 3 and 6 are two of the most common supplements given to dogs and cats, with the benefits of omega 3 being well recognised and demonstrated through a plethora of scientific studies. 

    Omega 3 and 6 are essential fatty acids, with some omega 3 oils containing two important polyunsaturated acids: Eicosapentaenoic Acid (EPA); and Docosahexaenoic Acid (DHA). Omega 3 is found in fish and plant-based materials, whereas omega 6 is found in plant material, eggs and meat. The type of omega 3 that you feed your pet is important. Omega 3 from fish oil contains the important polyunsaturated acids EPA and DPA, whereas omega 3 from plant-based materials, such as flaxseed oil, contains a different polyunsaturated acid known as Alpha-Linolenic Acid (ALA). ALA does not offer the same health benefits as EPA and DHA. Some species, including humans, have the ability to convert ALA to EPA and DHA. Cats, however, are one of the species that cannot convert ALA to EPA and DHA1, and dogs cannot efficiently convert ALA to EPA and DHA2. Accordingly, as discussed below, omega 3 from plant materials is of no benefit to cats and is of limited benefit to dogs.

    Further, whilst omega 6 is regularly added to commercial pet food and is of benefit to dogs and cats, studies have shown that omega 6 can have a pro-inflammatory response in dogs and cats with certain conditions, such as renal failure, or, inflammatory bowel disease3. Accordingly, omega 6 in any significant quantity could have a detrimental effect on the health of animals with these conditions.

    Whilst some pet foods contain omega oils, these might not be in sufficient quantities, or, quality, to pass on any real health benefit to your dog or cat. So a good quality supplement is advisable. In this article, we’ve explained what you need to know about omega 3 and omega 6.

    The Good

    Evidence suggests that omega 3 has a positive effect on the immune system, especially in older animals, and helps to lessen the symptoms of inflammatory diseases such as arthritis4. Other health benefits have been noted across several studies and it has led to the conclusion that omega 3 containing EPA and DHA can also aid in the management of renal diseases, hypertrophic cardiomyopathy, gastrointestinal disorders, high blood pressure, autoimmune disorders, skin disorders and behavioural issues such as excessive licking and pacing5. A lack of essential omega 3 and 6 in your pet’s diet can affect the quality of their coat and cause dull and greasy fur, itchy skin, and dandruff. Used as a general supplement omega 3 containing EPA and DHA is also believed to aid in organ health, bone development, help develop cognitive function, and help prevent the onset of diabetes and some cancers6.

    There are several types of omega 3 oils currently available for pets. The majority of these are marine oils. It’s important, however, to get the right marine oils. Omega 3 supplements containing fish oils from sardine oil, anchovy oil or farmed Atlantic salmon oil are excellent sources of omega 3 and come from sustainable fish stocks.

    The National Research Council published book, Nutrient Requirements of Dogs and Cats, states that the safe upper limit of omega fatty acids DHA and EPA in dogs is 2800 mg/1000 kcal of diet or 370 mg/kg0.75. For a dog weighing 10 kg, the safe upper limit would therefore be 2080 mg of omega oils7. Currently there is no confirmed safe upper limit for cats8. Accordingly, you should always read the manufacturers recommendation on dosage and if in any doubt you should consult your vet.

    The Bad

    As explained above, for dogs and especially cats, marine-based omega 3 oils are a healthier and more beneficial alternative to those that are derived from plant-based materials. An example of a plant-based omega 3 oil commonly used in pet foods and supplements is flaxseed oil.  As it only contains ALA its benefits are limited for dogs and non-existent for cats. Cats do not have the desaturase enzyme required to undergo the process of converting ALA to EPA and DHA and cannot derive any benefit from it. The reason cats lack this important enzyme links back to cats being obligate carnivores and not needing the ability to digest and utilise plant matter, the ALA having been converted to EPA and DHA by their prey.9 So little benefit is gained by feeding a cat omega 3 containing ALA, the only omega 3 oil found in plant-based materials such as flaxseed oil.

    Unlike cats, dogs can convert ALA to EPA and DHA, but not efficiently. Studies compiled by Lenox and Bauer have demonstrated that the conversion rate of ALA to EPA and DHA is very limited10, and in one study, investigators conducted a double-blinded, placebo-controlled, randomized trial with 29 dogs over a 10-week period, all of which were suffering from an inflammatory skin disorder. Some of the dogs were treated with flaxseed oil and some with omega 3 fish oils. The study confirmed that it took 2.3 times as much flaxseed oil as marine omega 3 oil to achieve similar improvements in their condition11. Accordingly, by ensuring that the omega oils contained in your pet’s food or supplements are sourced from marine animals containing EPA and DHA, you are providing your cat or dog with a more efficient supplement, which should provide them with better healthcare benefits.

    Further, whilst omega 6 oil may be of benefit to a healthy pet, it has been proven in studies to cause a pro-inflammatory response (as opposed to omega 3 which causes an anti-inflammatory response).12 Accordingly, if your cat or dog suffers from conditions such as inflammatory bowel disease or renal failure, foods and supplements containing high levels of omega 6 are not advisable. A good quality omega 3 fish oil supplement, however, has been demonstrated to be beneficial with these conditions13.

    As explained above a number of omega 3 fish oils are beneficial to your pet’s health. One that might not be advisable, however, is cod liver oil. All fish oils contain a level of vitamin A and vitamin D. Salmon oil and small fish oils such as anchovies and sardines have low to moderate amounts of vitamin A and D. Cod liver oil has high levels of vitamin A and can have high levels of vitamin D, both of which can be toxic if given to your pets in large quantities.14 

    If you are feeding your pet a prepared food that includes omega oils, it is best to be aware of what oils are stated on the label as well as the quantity of the omega oils contained in the food.  It is not mandatory for any pet food to include values of their omega 3 content15, and a product advertising itself as containing omega oils does not necessarily contain fish oils and could be limited to flaxseed, or, other ALA fatty acids. In some cases packaging will include a ratio of omega 6 to omega 3 (n-6:n-3), however, these ratios are often not a true representation of omega oils, as they are calculated including ALA and do not state the amounts of EPA and DHA16.  

    The Harmful 

    In 2002 the total world production of oils and fats was around 99 million metric tons, and 1.88% of this was sourced from “fish, fish liver, and other byproducts”17. Due to this substantial amount of fish being consumed annually, it is important to consider the sustainability of the product you are purchasing.  The production of fish oil is partially dependent on wild fish populations as well as farmed18, so it is important to ensure that the fish species used are not currently endangered and are from areas with a healthy and stable population. The Marine Conservation Society rate fish for consumption based on the sustainability of where they are fished from19

    Salmon oil derived from wild Atlantic salmon is best avoided, as their populations are not sustainably harvested. However farmed Atlantic salmon is readily available from sustainable sources, as are other species of salmon.

    Krill oil comes from Antarctic krill, a crustacean that contains above-average levels of protein as well as omega fatty acids20. The population of krill has been reported to be declining due to a combination of environmental issues such as global warming, and an increase in fishing. There are also concerns over the impact overfishing could have on the surrounding marine life that feeds off of these animals21. Currently, there are fishing quotas in place to help prevent the over-harvesting of krill and conservation research is taking place22.

    In addition to this the level of flame resistant chemicals polluting our seas, could mean that in the future we will have to review the impact this is having on these beneficial fatty acids such as marine-based omega 3 oils, and even now it is important to consider where a product is being sourced from.


    Multiple studies have shown the benefit of providing dogs and cats with omega 3 fish oil supplements. These supplements are palatable to dogs and cats and are easy to add to their food. Here at Thoughtful Pets we only stock omega oil supplements that are marine sourced which state the exact percentage of EPA and DHA, and we only stock omega oil supplements which have been produced from sustainable fish stocks.