Omega-3 Update: more info, more choices

By Jean Hofve, DVM

The headline read: “Omega-3 Fats Shown to Decrease Risk of Dying from Inflammatory Diseases.”

This study is a big deal, as it involved more than 2,500 human participants tracked over 15 years. Their diet was assessed using a food-frequency questionnaire.

The research, published in the American Journal of Clinical Nutrition, found that: “Women in the highest tertiles of total [omega-3] intake, compared with those in the lowest tertile of intake at baseline, had a 44 percent reduced risk of inflammatory disease mortality….” This particular study found a specific benefit of alpha-linolenic acid, the plant-based form of Omega-3.

Earlier research published in the same journal concluded that “Among the fatty acids, it is the omega-3 polyunsaturated fatty acids (PUFA) which possess the most potent immunomodulatory activities, and among the omega-3 PUFA, those from fish oil — eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) — are more biologically potent than alpha-linolenic acid (ALA).”

So what does this mean for our pets? Virtually all cats and dogs eating commercial pet food are deficient in Omega-3 fatty acids. Quite a few of the better foods are adding Omega-3 sources such as flaxseed meal. Ground flaxseeds are a source of alpha-linolenic acid, which has benefits in its own right. However, claims that it is a good substitute for EPA and DHA are false. Dogs and cats cannot convert more than 1-2% of it to essential EPA, and none to DHA. (See our article on Omega-3s for pets for details on these oils.) Therefore, our pets still need a direct (animal-based) source of those vital fatty acids. Those sources include:

Fish oil – This is the most well-known source of EPA and DHA. In some pet foods, fish meal is used to provide fish oil, but quality is an issue–it turns rancid quickly–and it is not as effective as direct supplementation. The quality and freshness of fish used in pet foods is of great concern. For instance, salmon should be a good source, but nearly all the salmon and salmon oil in today’s market comes from fish raised in “factory farms” where they are overcrowded, heavily parasitized, and loaded with toxins. “Atlantic” and “Norwegian” salmon oils are from farmed salmon. Moreover, salmon (as well as tuna, tilapia, grouper, bass, mackerel, and many others) are predatory (eat other fish), so in polluted waters, environmental toxins become concentrated in their flesh and fat.  However, wild salmon oil from the clean waters of Alaska is still a good source. Additionally, Nordic Naturals draws from sustainable stocks of abundant small non-predatory fish (sardines and anchovies) to create pure fish oil products for pets in both liquid and capsule forms.

Cod liver oil – Some of us “older” folks remember getting a giant spoonful of cod liver oil every day when we were kids. Since I grew up in a first-generation Norwegian family, you can bet I got my share! Nowadays, cod liver oil for people comes in different flavors, from lemon to peach, with added vitamins A and D. However, human products are not suitable for pets due to additives and the excessive A and D, which can lead to toxicity. More deceptively, since cod fishing in the Atlantic has been banned for years due to severe depletion of wild stocks (which have not recovered), the law allows other fish species to be referred to as cod. For cats and dogs, the safest and best quality cod liver oil is made by Nordic Naturals, which are sustainably harvested under strict supervision, and processed right on the dock for absolute freshness.

Krill oil – This product is making waves in the Omega-3 market. Krill are small shrimp-like crustaceans that live in the coldest waters. They are a major food source for whales and other marine mammals. Krill oil has primarily been popularized by Dr. Joseph Mercola of It does contain EPA and DHA comparable to fish oil. There are only two major manufacturers of krill oil capsules (and a couple of minor ones); so the highest-priced product is not significantly different from the cheaper ones. I tried krill oil for a while a few years ago. I liked the smaller capsules and the lack of “fish burps.” Then I found out that “fish burps” are actually a sign of rancidity, and they don’t occur if you use a better quality product in the first place! The environmental concern about krill oil is that it is being harvested in the same areas that whales, fish, seabirds, and other animals feed, without concern for sustainability. Whales are already being affected by this irresponsible harvesting; we cannot recommend krill oil for this reason.

Green-lipped mussel oil – A relative newcomer to the market, these mussels come from New Zealand and are specifically and sustainably grown for food, not taken from the wild, so there is no danger of over-harvesting. These shellfish contain not only EPA and DHA but more than a dozen other long-chain PUFAs (poly-unsaturated fatty acids) that have simply not yet been studied. It will be interesting to see how the research develops. The capsules are very small, so this may be advantageous for some pets, especially cats. At least one product also contains extra antioxidants.

Whatever form of Omega-3 supplementation you choose, you must provide these essential fatty acids to your pet to ensure a long and healthy life!



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16 comments for “Omega-3 Update: more info, more choices

  1. Jean Hofve DVM
    September 6, 2014 at 7:14 am

    Dosage depends on the pet’s weight; you can extrapolate from the dosing charts on the Nordic Naturals products to get the milligram recommendations:

  2. MetteN74
    September 2, 2014 at 7:14 am

    Sorry, one more question:
    Moxxor is not available in Denmark (so far, to my knowledge) and Nordic Naturals only in the human grade version.
    As human grade fish oils vary very much in concentration – is there any guidelines or recommendations on how much EPA and DHA (in mg) a cat should have on a daily basis?

    Thank you again – so much great information on this site!

  3. Jean Hofve DVM
    August 24, 2014 at 9:28 am

    High quality, very pure fish oil has been processed in such a way as to remove all proteins. Since allergies are nearly always to proteins, this makes fish oil safe for fish-allergic cats. However, poor quality and inexpensive fish oils may still contain proteins and may cause an allergic reaction. That is why we recommend only MOXXOR green-lipped mussel oil and Nordic Naturals fish oils for pets; we are confident that these products are the safest and best quality products available today.

  4. MetteN74
    August 22, 2014 at 5:42 am

    If fish is a potential allergen to cats, is it safe to give them fish oil?
    And if my cat is allergic (which I’m trying to find out), can I still give him fish oil for the fatty acids?

  5. steph
    April 24, 2013 at 9:02 pm

    Thank you for the information!
    This oil does sound like a good fit for my cats. I had never heard of it.

  6. jhofve77
    April 24, 2013 at 12:55 pm

    Nordic makes liquid products in smaller bottles, if you want a liquid. But frankly, once the bottle is opened and air gets inside, oxidation will occur regardless of how many times it is opened. My favorite supplement for cats is Moxxor, which comes from New Zealand greenlip mussels; it’s very small capsule that’s easy to give (unlike the gigantic fish oil ones!). It has not been artificially concentrated, so it’s not a “high dose” supplement, but it is completely bioavailable and contains several Omega-3s beyond EPA and DHA that may be even more powerful. See:

  7. steph
    April 23, 2013 at 9:26 am

    My veterinarian has advised me to use fish oil in gel caps rather than the liquid form in a bottle because the repeated opening of the bottle will allow the oil to become oxidized. He also recommended a much higher dose of fish oil for my cat’s arthritis. I’d like to use Nordic Naturals, but their instructions for cats are a much lower dose. I am thinking of using the bottle labeled for dogs so I can deliver the higher dose.
    Any thoughts? (Especially regarding the gel caps vs the liquid).
    Thank you very much

  8. Elaine Alfaro
    January 22, 2012 at 3:49 pm

    Thank you, Dr. Hovre,
    I ordered the Moxxor product and have been giving 1 capsule to Izzy every 3 days. Luckily, he takes it in a Pill Pocket and I don’t need to bother with mixing it in his food.
    (I’m not crazy about the ingredients in the pill pockets, but they work so well with
    him, and there’s just no way I could pill him). I’m just glad to be giving him a quality source of EFA’s because they seem to help in so many different ways in the body.
    Izzy has hypertrophic cardiomyopathy (he’s a Maine Coon mix probably.. not sure as I adopted him 1 1/2 years ago at the age of 6). Hopefully, this will help his heart as well as his greasy fur/dandruff that showed up on his back a couple of months ago.
    I know you can’t prescribe/diagnose anything over the internet, but I was wondering
    about increasing the Moxxor to every other day. According to Imelda at Celestial Pets she says that one a day is fine, and sometimes more is recommended. However, the human maintenance dosage is 2 caps per day, so 1 per day does seem way too much, as you suggested.
    Is there a way to know if I’m giving him too much EFA’s? Any symptoms, perhaps?
    Thank you

  9. jhofve77
    December 22, 2011 at 10:13 am

    Green-lipped mussels are still raised in the ocean so they are slightly fishy-smelling but nothing like fish oil. They are so small I just pill my cats with them. They’re pretty potent so need not be given daily. Haven’t heard about calamari oil; what will they think of next? EPA is more important than DHA for adult animals, so best to look for a supplement that has a higher EPA level.

  10. Elaine Alfaro
    December 21, 2011 at 1:13 pm

    My cat, Izzy, doesn’t like the taste of fish oil unless it’s mixed into a fish flavored food,
    and I try to avoid fish except for occasional treats. I’m curious about the green lipped
    mussels; are they very fishy or strong flavored? Do most cats accept it in their food?
    And how much would one use on a daily basis for a cat? I’m trying emu oil right now with Izzy, but I can tell by his coat quality that it’s not as rich in EFA’s as fish oil. I’ve also heard that calamari (squid) oil is a rich source of EFA’s, especially DHA. Do you have any experience with this oil? I’m trying to find something that will benefit Izzy and he will also tolerate.

    p.s. Dr. Hofve, I love this website and use it as a resource quite often. Thank you for helping all of us cat lovers keep our companions healthy and happy!

  11. jhofve77
    September 21, 2011 at 10:16 pm

    There is no whale anything in Nordic Naturals; and the fish are not farmed. Farming (especially salmon) is terrible for the fish and the environment! Here’s a link to a short video about how they produce their cod liver oil, I think it’s kinda fun to watch. Norway sets strict limits on the catch to protect the fish, and the cod are processed right on the dock where the fishing boats come in. Nordic’s fish oil is from wild sardines and anchovies from the South Pacific. None of the species used for Nordic products are endangered. If you’re still getting “fish burps” then I’d recommend calling them directly about it (800.662.2544 x3), because they are so careful about quality and freshness. All their products are independently tested, and I know they would want to hear about any problems.

  12. Aurora daniels
    September 21, 2011 at 3:06 pm

    I still get fish burps from Nordic naturals so if it is the case that high quality is vetted then I’m unsure that Nordic naturals are they way, although they certainly have the price tag. I have been told that fish oils from Norway contain whale oil and I am against whaling so now I am concerned about Nordic naturals. I was told though that the fish they use for Nordic naturals come from clean water and that the fish are farmed so you should be getting toxins nor harming wild fish supplies. Does anyone know if any of this I’d true please? Thank you

  13. jhofve77
    May 31, 2011 at 12:34 pm

    There’s a mixture of myth and fact here, so let me try to sort it out.

    First, salmon are carnivorous; they don’t eat algae. I agree that farm-raised salmon are an unhealthy choice, but not because of Omega-3s. Farmed salmon are fed fish meal (which, depending on the species and source, may contain heavy metals, PCBs and other toxins), corn (likely GMO), soy (almost certainly GMO), fungicides, antibiotics, and other drugs; not to mention the environmental devastation created by highly polluted pens containing millions of diseased and parasite-ridden fish sitting all along the whole north Atlantic coastline. The last time I checked, farmed salmon contained about the same amount of Omega-3s as wild salmon, but far more Omega-6s due to the unnatural corn and soy in their diet.

    Algae are primarily a source of DHA, but from what I can tell none of Udo’s oils contain any significant amount of EPA. DHA is primarily needed during fetal development, although it is also used in adult animals in the eyes and brain. EPA is more important in adult animals, and more of it is needed. Udo’s oils contain large amounts of Omega-6, which our cats don’t need; Omega-9, which is not essential; and plant-based Omega-3 (e.g. flaxseed oil) that cats can’t convert to either EPA or DHA.

    Udo’s “DHA blend” contains 100 mg of DHA but only 3 mg of EPA per tablespoon (a truly beneficial dose is more in the range of 100-200 mg EPA). It takes more than 14 capsules (1000 mg each) to make a tablespoon of oil; so splitting 1/14th of 3 mg is giving your cats no EPA at all, and not very much DHA. I didn’t see any EPA or DHA in their other products. Even Udo’s DHA oil is not “pure” algae oil; in fact, algae is listed 5th, after flax seed oil, sunflower seed oil, sesame seed oil, and evening primrose oil. Flaxseed oil is about 53% alpha-linolenic acid; the other three are mostly Omega-6.

    As far as sensitivity (by which I presume you mean allergenic potential), fish oil can be purified to contain no fish proteins; this is always done by the more reputable companies, such as Nordic Naturals. Studies won’t be done until there is profit to be made from them…I am not holding my breath!

    I would love to find a non-animal source of Omega-3s (for vegetarians and vegans, as well as reasons of renewable resources and animal welfare and cruelty), although I suspect that cats will always do better with an animal-based oil because of their purely carnivorous physiology. I used to recommend flaxseed oil, until research clearly showed that the conversion rate of alpha-linolenic acid to either EPA or DHA, even in humans, is less than 2%. I can’t recommend krill oil because indiscriminate harvesting is adversely impacting whales, birds, and other marine animals. The product I’ve found that does meet my criteria is Moxxor, which is made from New Zealand greenlip mussels. See for more information.

  14. Penelope Gordon
    May 28, 2011 at 3:47 pm

    Algae oil is a non-fish, lower on the food chain, more sustainable source of DHA for cats and vegetarians alike. Algae is the source of Omega-3 for salmon – hence the reason why farm-raised salmon is generally not a good source of Omega-3. I’ve only found the pure algae oil in capsule form; Udo’s Choice is the brand that I buy. Every evening I puncture the end of one capsule, squirt the contents over the (raw) food in three food dishes, and drop the empty capsule into the third dish. Personally I can’t stand the taste of algae oil – I’m a vegetarian and the algae oil is, well, really fishy tasting – but my three guys gobble up their food regardless of whether it’s been topped with algae oil.

    I assume that cats that are sensitive to fish are not also sensitive to algae oil, but I’d sure like to see a study.

  15. jhofve77
    May 27, 2011 at 7:29 am

    Good quality fish oils, such as Nordic Naturals, are highly purified, and do not contain fish proteins that could trigger an allergy. Please also see my article at Only Natural Pet Store, which discusses how to prevent food allergies.

    An excellent non-fish source of Omega-3 oils is New Zealand greenlip mussels; the product I recommend is called Moxxor. See

  16. Diana Crandall
    May 27, 2011 at 12:48 am

    I am looking into diets for my cats that don’t contain the most common sources of allergens. And, after reading some of the information on omega fatty acids, I want to make sure they will be included in their diets. The only problem is that fish is on the list of foods that are most likely to cause senstivity in cats and dogs, but all of the forms of omega fatty acids besides flax, is fish based. How do I deal with that contradiction? Sorry, that sounded a bit snide, and that is not my intention. I’m just hoping for a suggestion on what non-fish based source I can use. Just frustrated because I want to do what’s best for my wonderful pets.

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