Answers: Flaxseed Oil for Kitty?

Updated: Friday, May 10, 2019 02:18 PM

Published: Saturday, March 21, 2015 12:47 PM

Written by Margaret Gates

I know cats need omega-3 fatty acids, as we humans do. I take flaxseed oil supplements myself for the fatty acids they contain. Can I give flaxseed oil to my cats?

The quick answer is yes, but it's not a good idea. EFAs are one of the most common supplements given to cats and dogs. Omega-3 fatty acids tend to reduce inflammation, while omega-6 fatty acids tend to increase inflammation.¹ There are also omega-7 and omega-9, but they are not considered essential, at least for humans.

EFAs are abundant in the oil from fish, but are also found in many plant sources such as the oil from flax and soybeans. Some nuts and green vegetables also contain omega fatty acids, such as walnuts, Brussel sprouts, kale, spinach and some salad greens. But, the forms they take is the crucial difference when it comes to cats.

Fish oil contains two types: eicosapentaenoic acid and docosahexaenoic acid. Vegetable sources contain another type of EFA, alpha-linolenic acid. Humans, along with many other animals, can convert some ALA to EPA and DHA in the body, so we can use ALA as a fatty acid source.² Cats, on the other hand, can't do this. They must have a pre-formed source. Adding any of these plant-sourced FAs to a cat's diet just doesn't work.

As obligate carnivores, cats evolved eating prey diets rich in animal fat, which contained omega-3 and omega-6 fatty acids in the pre-formed state. The prey animals had already converted plant-sourced ALA into EPA and DHA for them, so cats lost the ability – and the need – to convert it themselves. This is why plant-based FAs don't work for cats; you are skipping the intermediate step the prey animal provided.

Fish oils are typically used as a good source for omega fatty acids, but other animal fat sources also contain them, although in smaller amounts. Poultry, eggs, pork, beef and other meats all contain a range of omega fatty acids, so fish is not absolutely required in a cat's diet. But, fish and fish oil are some of the best sources, as they are high in omega-3 compared to omega-6.

Since most of the meat we feed our companion cats is likely to be from modern farms and thus would have a much higher omega-6 content, adding a good source of omega-3 is important to try to bring the ratio of omega-6 to omega-3 closer to the ideal. The ratios are expressed like this: 1:1, with the first number being omega-6 and the second omega-3. The ratio of these two EFAs in a cat's diet should be about 6:1 to 2:1, based on the ratios found in wild meats.³ Animals that are farmed typically are fed diets very different from what they would eat in the wild. This affects the fatty acid ratio rather dramatically, making the amount of omega-6 much higher. Fish oil has an approximate ratio of 1:8.

You can also feed oily fish directly to your cats. Up to three times a week, you can feed fish such as salmon, sardines, mackerel or anchovies. If using canned fish, be sure it is water-packed. You can also increase the omega-3 that your cat gets by using omega-3 eggs or feeding pasture-raised poultry or grass-fed beef. Omega-3 eggs are from hens fed a diet that increases the omega-3 content of their eggs to levels closer to those found in wild birds. Pasture-raised and grass-fed animals are eating a diet that is more natural for them. Their meat has a much better ratio than grain-fed animals. Grain-fed beef can have an 18:1 ratio while grass-fed beef has about a 3:1 ratio.⁴ Similar ratios can be found for poultry and other meats when comparing conventionally-farmed versus pasture-raised.⁵

You can add fish oils to homemade cat food or when you add other supplements to purchased ground raw cat food that is unsupplemented. Or, you can open a capsule and dribble it directly onto your cat's food. Salmon oil is a common fish oil fed to cats. Small fish oil, made from sardines, herring, anchovies and/or mackerel, is also a good choice, especially if you have a cat that doesn't like the taste of salmon oil. Small fish oil is made from fish that are low on the food chain and usually sustainably harvested.

Note: Feline Nutrition provides feline health and nutrition information as a public service. Diagnosis and treatment of specific conditions should always be in consultation with your own veterinarian. Feline Nutrition disclaims all warranties and liability related to the veterinary advice and information provided on this site.

Margaret Gates is the founder of the Feline Nutrition Foundation.

1. PC Calder, "n3 Polyunsaturated Fatty Acids, Inflammation, and Inflammatory Diseases,"The American Journal of Clinical Nutrition83, no. 6, June 2006, 1505-1519.

2. H Gerster, "Can Adults Adequately Convert Alpha-linolenic Acid (18:3n-3) to Eicosapentaenoic Acid (20:5n-3) and Docosahexaenoic Acid (22:6n-3)?" International Journal of Vitamin and Nutrition Research 68, no. 3, 1998, 159-173.

3. Steve Brown, "Care to Compare? Wild vs. Domesticated Prey."

4. Ponnampalam EN1, Mann NJ, Sinclair AJ.EN Ponnampalam, NJ Mann and SJ Sinclair, "Effect of Feeding Systems on Omega-3 Fatty Acids, Conjugated Linoleic Acid and Trans Fatty Acids in Australian Beef Cuts," Asia Pacific Journal of Clinical Nutrition 15, no. 1, 2006, 21-29.

5. "Nutritional Benefits of Higher Welfare Animal Products," Compassion in World Farming Report, July 2012.