Is Fish Oil Healthy for My Dog or Cat?

Fish oil is often recommended for dogs and cats for the omega 3 fatty acids it contains. Omega 3 fatty acids possess anti-inflammatory properties that can be useful for inflammatory conditions like allergies, arthritis and heart disease. However, there is more to this story than just ‘fish oil = healthy, anti-inflammatory qualities’, and our discussion on this topic will help to educate you and support our evolving, less than enthusiastic position on fish oil for general use as a supplement.

The Health Benefits of Fish Oil

The health benefits of fish oil that receive the most attention include its ability to aid in the treatment of various heart diseases, lower high cholesterol, reduce inflammation associated with  arthritis, allergies, skin issues and inflammatory intestinal conditions, treat depression, help remedy eye disorders and help to prevent neurodegenerative diseases such as MS, Parkinson’s Alzheimer’s disease.

Most of the health benefits of fish oil can be attributed to the presence of the omega 3 fatty acids Docosahexaenoic acid (DHA) that provides nutrients important for proper fetal development including the eyes, brain and nervous system and Eicosapentaenoic acid (EPA) that provides the primary anti-inflammatory, immune system boosting and platelet aggregation inhibiting properties.

Contaminants in Fish Oil

Fish oils can contain numerous different contaminants, however the ones most focused on include PCB’s, mercury and dioxin. These are generally the result of industrial pollutants that are directly discharged into waterways or washed into our oceans due to rainfall via runoff or by cleaning the air from this particulate pollution as it rains.

A recent study provided some good news when it found that the majority of fish oil products tested contained only very low levels of mercury, ranging from one to six parts per billion per serving. That range is far below the upper safety limit of 100 parts per billion set by the Global Organization for EPA and DHA Omega-3s, or GOED, an industry trade group.

What this means is that taking a fish oil supplement can be safer than eating the fish itself as companies use techniques such as molecular distillation to cleanse fish oil of impurities. However, this “cleansing” of fish oil can have its own drawbacks. That is because the EPA and DHA in fish oil are delicate, polyunsaturated oils that go rancid very quickly creating potentially harmful free-radicals when exposed to heat, light or oxygen. This is why  it is so important that fish oil contains antioxidants like vitamin E or rosemary extract. Because of this potential for rancidity you should check something called the “peroxide value” on the fish oil’s Certificate of Analysis. This is a measure of rancidity reactions in the oil that have occurred during processing and/or storage and should be less than 5 meq/kg.

Due to distillation you should also make sure that the fish oil you purchase is in its natural triglyceride form because that is how it is found in nature. This issue occurs because during the distillation process, in order to to purify the oil, it is necessary to add ethanol (an industrial alcohol) to form a synthetic substrate. In a vacuum, the mix is then distilled and the result is a concentrated omega-3 ethyl ester solution. The benefit is a pure fish oil, and the ability to concentrate the healthy omega-3’s like DHA and EPA. This is why almost all of the “highly concentrated” fish oils are in the ester form. Unfortunately, research is now showing that although this form of fish oil can yield higher concentrations of omega-3s, it is not absorbed nearly as well as natural fish oil. Manufacturers can in fact convert the omega-3 concentrated ester form back into the healthy triglyceride form, but most manufacturers do NOT do this because the costs are significantly higher.

Why Do Contaminants Accumulate in Fish?

The consumption of fish is by far the most significant source of ingestion-related mercury exposure in humans and animals. Mercury is present in only very small concentrations in seawater. However, it is absorbed, usually as methyl mercury, by algae at the start of the food chain. This algae is then eaten by fish and other organisms higher in the food chain. Fish efficiently absorb methyl mercury, but only very slowly excrete it so mercury will accumulate in tissue, which is called bioaccumulation.

The older that such fish become, the more mercury they may have absorbed. Anything that eats these fish also consumes the higher level of mercury that the fish have accumulated. This process explains why predatory fish such as swordfish and birds like ospreys and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone.

Species on the food chain can amass body concentrations of mercury up to ten times higher than the species they consume. This process is called biomagnification. For example, herring contains mercury levels at about 0.1 parts per million, while shark contains mercury levels greater than 1 part per million. That is why in the past we have always recommended fish oils from smaller fish like sardine and anchovies that are closer to the beginning of the food chain.

Is Fish Oil Necessary for my Dog or Cat’s Diet?

When people typically talk about fish oil they are referring to the content of the omega 3 fatty acids EPA and DHA. So the answer to the above question would be no, a healthy dog or cat does not require supplementation with fish oil.

DHA is important for proper brain, nervous system and eye development. Fortunately, nature take cares are of this by increasing DHA production in the mother that is transferred to puppies and kittens during pregnancy and lactation. As I mentioned previously DHA supplementation is not necessary, however it can be beneficial for pregnant females and also to help maintain the health of the eyes, brain and nervous system to treat various imbalances or weaknesses in this tissue.

As far as EPA goes, this fatty acid has anti-inflammatory benefits that will be helpful for issues like arthritis, autoimmune conditions, allergies and so on. This does not need to be supplemented in healthy animals because they can derive what they need from a healthy diet that includes grass fed meats, free-range eggs, organ meats, organic greens and some fish. You may notice that I specifically said a “healthy” diet. That is because if you feed a typical pet food that uses factory farmed meat that is finished on feed lots, low-quality farm-raised fish, flours and grains, factory farmed eggs (well you get the picture), you will be feeding your canine or feline a diet that has an unhealthy, or pro-inflammatory, ratio of omega 6 to omega 3. In this case you can change the diet over to healthier foods or include fish oil supplementation in your pet’s diet.

Are There Alternatives to Fish Oil?

Since dogs and cats do not convert the essential omega 3 fatty acid alpha linolenic acid to EPA and DHA efficiently, supplementing your dog with oils like flax seed, hemp seed, chia seed and other similar oils will not do the trick. Even though those other oils do have various health benefits, fish oil has been the primary provider of the beneficial omega 3 fatty acids EPA and DHA up until recently.

We have always been a proponent of algae for all their important nutrients, but they have suffered from the same problems as fish oil and that is pollutants. That was until we found BioPreparation, which is a balanced blend of four algae that is grown in indoor bioreactors where the environment can be isolated from outdoor pollutants. While these algae are a great source of fatty acids they are not a concentrated source. Fortunately, with all the issues related to sustainability and pollution, algae has started to be grown indoors for the purpose of providing a cleaner, more sustainable source of the omega 3 fatty acids EPA and DHA. This is wonderful news and makes algae oil the only real alternative to fish oil that is both less polluted and highly sustainable.

In Conclusion

Well, is fish oil good for your dog or cat? From what we discussed above, it really depends. It can be in the case of various disorders that can benefit from the addition of EPA and DHA, the omega 3 fatty acids found in fish oil. However, it depends strongly on the quality of the fish oil you decide to use in your supplement regimen. If you choose the cheapest fish oil, without doing further research on that brand, you may be doing more harm than good.

For healthy dogs and cats fish oil is really not necessary, especially when you are feeding healthier grass fed foods naturally higher in omega 3 fatty acids. Though, as mentioned previously, if you feed a typical store bought brand of kibble pet food, your canine or feline could benefit from the increase in omega 3 fatty acids from fish oil. However, the issues of quality and sustainability will be spurring us to make the transition to obtaining our EPA and DHA from algae oil for ourselves and our customers in the future.


Health benefits of fish oil. Retrieved from

What are fish oils? What are the benefits of fish oils? Retrieved from

Mercury in fish. Retrieved from

Sisskind, S. The truth about fish oil. Retrieved from

Kresser, C. The definitive fish oil buyers guide. Retrieved from

Whole Food vs Synthetic Vitamins

We are whole food proponents and have been for quite some time… but weren’t always. For a period of time, like most people, our supplement regimen consisted of a popular multivitamin supplement along with a variety of additional supplements that were “in the news”. I was quite happy with that regimen until I started to educate myself and realize that those educational articles in the monthly “health” magazine were not truly educational articles written for my benefit, but instead primarily advertisements.

My epiphany was not overnight, but instead a journey combining education, common sense and personal experience that I applied to the health of not only myself and my wife but to our animals as well. Quite simply, I came to understand that animal biology has never evolved to accept synthetic vitamins no matter how much vitamin and food manufactures try to convince us otherwise. That is why The Pet Health and Nutrition Center supplements and remedies focus on organic, whole foods and always will. The success we have with both people and animals is quite rewarding, yet even we are sometimes pleasantly surprised with the simplicity in which chronic conditions are alleviated.

How the Body Utilizes Nutrients

Whole foods go through three kinds of processing in the body. First there is digestion, during which food is transformed into substances that can be utilized by cells for energy. Next, these digested substances are absorbed by the body when food moves from the intestines into the blood. Lastly, metabolism occurs when food substances are used as energy sources or building blocks for other purposes needed by the body.

Bodily processes are quite complex, yet extremely efficient, and you can’t help but see the majesty of this creation, our body, that we take so much for granted on a daily basis. However, as great as our capacity to utilize natural nutrients from food is, organisms lack the capacity to properly utilize synthetic nutrients derived from chemical processing.

A body experiences difficulty trying to regulate the absorption of synthetic vitamins and optimize their levels and this inability to reach homeostasis, or balance, so easily accomplished with whole foods, can have very serious short and long term consequences. In reality, synthetic vitamins are received by the body similarly to pharmaceutical drugs, and like all drugs they can potentially disrupt normal metabolic functions often with devastating side effects.

To get all of the healthy, disease-fighting benefits from what we eat, or feed to our dogs and cats, it’s best to obtain nutrients from whole foods rather than from synthetic substitutes. After this recent decades long vitamin craze, more and more studies indicate that an animal’s body utilizes nutrients from whole foods better and that the desire by manufacturers to replace real nutrients with cheaper synthetic ones in their processed human and pet foods is not living up to the hype. For instance, a recent study from Oregon State University found that an important phytochemical in broccoli and other similar veggies is poorly absorbed and much less beneficial when isolated and taken in supplement form and this study is far from alone in its conclusion.

“The whole nutrient complex is greater than the sum of its parts.”
-Dr. Royal Lee

Yellow Urine, Excesses and Toxins

It is really weird, but when I was younger and utilized synthetic vitamin supplements I remember somehow feeling like I was doing a good thing when my urine turned bright yellow within a very short time of taking a supplement. I viewed it like “wow, this thing must really be working!”. Of course now I realize that I was just peeing out the majority of what I paid for. Did you ever notice the bright color of your urine or your pet’s urine after taking a synthetic vitamin supplement or just from all those synthetic vitamins found in commercial pet foods?

Urine should be clear to straw colored, never yellow. Yellow urine is a sign of dehydration, the body attempting to rid itself of excesses or potentially a more serious medical condition. What is amazing is that I can take a tablespoon of bee pollen, loaded with bright yellow plant pigments and B vitamins and my urine will never turn yellow nor will that of my dogs. Yet, one tiny little commercial multivitamin and there it is – bright yellow urine that is the consequence of my liver and kidneys working overtime to remove excess synthetic chemicals.

All foods nowadays can contain some potentially toxic substances since there are many present in our environment. Yet, these toxins are often negated by the presence of natural compounds found in healthy, whole foods. For example, the nitrates found in carrots can be toxic at high doses. However, nitrates are not concentrated in carrots and they are neutralized by the vitamin C also found in carrots – the benefits of the synergy of whole foods. This can not be said about synthetic substances which are typically isolated away from other synergistic substances they would be found alongside in nature.

This talk of toxins brings up a funny story (but not really funny). Recently, in the news there was a story concerning a large, popular vitamin retailer whose multivitamins were independently tested. This testing indicated rather high levels of lead, far in excess of what are considered acceptable levels. I thought to myself how sorry I felt for those people happily taking their synthetic multivitamin supplement and consuming large amounts of lead at the same time, all the while thinking that they are doing the right thing for their health. I was feeling quite above the fray until I remembered that years ago I took the same multivitamin supplement and gave one to my wife as well.

Lots of Money to be Made in Supplements

Problems usually begin to arise when money comes into play and the supplement industry is no exception. You see, there isn’t much money in an apple per se, but there is tremendous amounts of money if you can convince people that the most talked about nutrients found in apples are found in this great new supplement and it is so much better than eating an apple…

Just think of the advantages – mass produced synthetic substances (pennies), shelf life (years), transportation costs (a fraction of shipping fresh, whole foods) and all too often you can take up most of a bottle with cheap fillers. This all leads to HUGE profits for large supplement manufacturers who can then afford to take out full page advertisements lauding the latest new fad and telling you it is the same, or better, than eating the real thing or feeding your dog or cat a whole food diet.

Toxicity Side Effects of Excess Fat Soluble Vitamins

For years we have all been aware of one story or another indicating the dangers of certain vitamins. I remember 15 or 20 years ago when the stories about the harmful effects of beta-carotene began to come out in relation to lung cancer. At the time I wasn’t sure if that meant I shouldn’t eat so many carrots or other foods that contained beta-carotene. Of course, in time I began to make the distinction between synthetic beta-carotene and that found in whole foods.

I have recently become alarmed at the increasing usage of vitamin D in large doses. Research has been showing that the body does not utilize the vitamin D obtained through supplements as it does that obtained from whole foods or sunshine. More recently I read a study that indicated that supplementing with higher doses of vitamin D is now being associated with damage to the heart. Below are some more potential dangers related to supplementing with synthetic vitamins:

Vitamin A: abdominal pain, vomiting, headache, lethargy, eczema, patchy hair loss, edema, anemia, respiratory tract infection, chronic liver disease

Vitamin E: allergic reaction, breathing impairments, swelling of the tongue, fatigue, headache, nausea, blurred vision, excessive bleeding (anticoagulation due to inhibition of vitamin K), increased oxidative stress, increased hypertension, decreased life span

Vitamin K: supplementation with a synthetic form of vitamin K Menadione has been associated with liver damage. Some reports indicate a significant association between high intramuscular levels of vitamin K and cancer.

Vitamin D: even though vitamin D poisoning is rare, toxicity can occur under certain medical conditions such as primary hyperparathyroidism, tuberculosis and lymphoma. Note that vitamin D is completely safe when produced by the body itself through UV sunlight exposure.

As for the water soluble vitamins, these have been generally considered safe simply because water soluble vitamins are not stored by the body. Since any excess of water soluble vitamins is excreted in the urine, they presumably can’t accumulate in toxic levels and therefore are regarded as safe. However, an article in the American Journal of Clinical Nutrition (Vol. 87, No. 1, 142-149, January 2008) examining the effect of vitamin C on training efficiency in animals and humans, reveals that supplementation with vitamin C ascorbate devastates muscle, causing impairment in mitochondrial function, loss of endurance, and inhibition of the body’s own antioxidant enzymes superoxide dimutase (SOD) and glutathione peroxide. In other words, synthetic vitamin C at certain levels promotes oxidative damage in the body instead of performing as an antioxidant as promoted.

In addition to toxicity issues discussed above, there is another danger of excess with synthetic vitamins. When too much of any particular vitamin is taken, it tends to upset the balance of natural vitamin metabolism and can lead to a deficiency of other vitamins. This has been clearly demonstrated in the case of the various members of vitamin B complex.

For example, an excess of certain B factors, such as thiamine [vitamin B1], has been found to produce compensatory deficiency of other factors, such as pyroxidine [vitamin B6]. This shows why it is much better to use the entire vitamin B complex, as provided by natural, whole food sources of the vitamin.

In Conclusion

Synthetic supplements are often processed at high temperatures, contain residual petroleum derived chemical solvents (such as benzene – a potent carcinogen) and tablets are often coated with methylene chloride another carcinogenic material. According to Dr. Zoltan P. Rona, M.D., “Although most healthy people will have no obvious side effects from ingesting small amounts of toxins found in cheap vitamins, the long term consequences of continuous, daily intake are potentially dangerous. Over 7% of the population displays sensitivity to these chemicals.”

Could the above pertain to you or your dog or cat? Could the processed food you feed your family or pets fortified with synthetic vitamins to make up for its lack of nutrition be affecting your family’s health? There is a reason that we highly recommend whole food diets and natural, whole food supplementation – they are safer and much healthier for your family!


Pitchford, P. (2002). Healing with whole foods: Asian traditions and modern nutrition (3rd ed.). Berkeley, CA: North Atlantic Books.

Thibodeau, G.A., & Patton, K.T. (2008). Structure & function of the body. St. Louis, MO: Mosby.

Vitamin poisoning: are we destroying our health with hi-potency synthetic vitamins? Retrieved from

Natural vitamins vs synthetic vitamins – beware of studies. Retrieved from

Lee, R. The truth about vitamins. Retrieved from