Fish Oil: Do’s and Don’ts

Fish Oil: Do's and Don'ts

Fish Oil has been touted as a miracle anti-inflammatory in western and alternative circles for many years and it can have many health benefits if it is pure, fresh and from a good source.

I think people should try to get your omega 3’s from eating wild fish from a great source a couple times a week before considering supplementation. Wild fish have more nutrient density than fish oil alone including important co-factors like selenium, Vitamin D, iron and magnesium.

It is really important to focus on the highest quality when picking a fish or cod liver oil because these oils can do more harm than good if you don’t shop carefully.

Fish Oil: Do’s and Don’ts

Here are tips to remember about fish oil or cod liver oil:


  • Buy one that is cold processed to prevent undoing any anti-inflammatory benefits.
  • Buy in small batches (not like a Costco brand because it will spoil before you finish it).
  • Keep your dose to a reasonable levels of no more that one or two grams per day.
  • With fish oil, check that you are actually getting a good amount of EPA and DHA (about 500 mg of each per day).
  • Always take fat soluble vitamins A and D together because they are synergistic. Make sure the ratio is balanced the way it is in cod liver oil.
  • Look for a manufacture date to help you determine freshness: such as on this cod liver oil.
  • Remember that the Vitamin A in CLO can help protect the polyunsaturates from oxidation.
  • Get a CLO that is fermented because it makes the vitamins more bio-available for the body.
  • Decrease omega-6 in the diet because omega-3 supplementation cannot make up for grain fed meat and industrial seed oil consumption.
  • Do smell your oil and if it smells like a rotten fish it is not fresh. Instead, fish oil capsules should smell like the ocean.
  • Look for a fish oil that has Vitamin K2 which is helpful in blood clotting, heart disease protection, healthy skin, strong bones, proper brain function, proper growth/ development and cancer prevention. Vitamin K2 is available in cod liver oil.


  • Don’t store your fish or cod liver oil in a warm place or outside the fridge.
  • Don’t buy fish oil or Cod liver oil that comes in a clear bottle.
  • Don’t take fish oil or Cod liver oil away from a fatty meal because the fat soluble vitamins A, D and K will be absorbed.
  • Don’t be afraid of taking vitamin A as long as it is in proper balance with Vitamin D like in this CLO
  • Don’t buy farmed fish that have unnatural amounts of contaminants and antibiotics in their food.  Farmed fish are fed gmo corn and soy and will have an unhealthy balance of omega-3/6 that will be passed on to you.
  • Don’t buy a fish oil without a Certificate of Analysis, which screens for levels of contamination of PCB’s and heavy metals.
  • Don’t buy GMO salmon (if approved possibly by Feb 2013) because of unknown changes to our DNA from eating modified food.
  • Don’t convince yourself that taking fish or CLO can make up for a standard American diet.
  • Don’t overlook the other ingredients that are used as fillers such as corn, soy or canola oils that are highly inflammatory.
  • Don’t forget to look for a company that is using sustainable methods of fish harvesting. Approval from the Marine Stewardship Council is a good sign.

Which is one is best?

The only brand of fish oil that I think is properly prepared is the cod liver oil from Green Pastures. It is cold pressed and from wild fish. This CLO is more like a food so it does not have the exact measurements of DHA and EPA on the label. That is because there are so many compounds in food that work together and we do not understand them enough to separate out. That is why it is important to eat whole foods as much as possible. That being said, I am not sure many people would actually eat cod liver if was not made into supplement form.

Order the best cod liver oil on the market, especially if you are not eating fish a few times a week.

Many of my clients have taken this brand and they reported less cold’s, improved energy and better skin. Let me know how it works for you!

Are there any criteria for choosing a good fish oil supplement that I have overlooked?



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lCaitlin Weeks BA, NC, CPT is a full time blogger and author. She has many years of experience as a Certified Nutrition Consultant, C.H.E.K. Holistic Lifestyle Coach, and professional personal trainer in San Francisco, CA. Caitlin has had success conquering obesity after a lifelong struggle with her weight. Since 2009 she has been winning the battle against Hashimoto’s Thyroiditis using a Paleo diet. She truly believes in the mind- body connection for healing and is certified EFT practitioner. She is committed to educating others about the benefits of traditional/ancestral foods and efficient exercise.

DISCLOSURE: Not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations is at the choice and risk of the reader. Grass Fed Girl may receive monetary compensation or other types of remuneration for endorsement, recommendation, testimonial and/or link to any products or services from this website.


  1. says

    Now that the government has passed the law allowing salmon to become frankenfish which will eventually affect all the wild salmon, how will we be able to get Omega 3 without being poisoned?

  2. says

    I appreciate you taking the time to help your readers understand the ins and outs of fish oils. I was heavily involved in the comments on Chris Kresser’s post that you linked to. I understand that the fermented cod liver oil is popular in the paleo world, especially among followers of Weston Price. However, after studying the science of omega-3s for almost a decade, I don’t think the science behind the fermented CLO recommendation stands up to scrutiny. I appreciate the preference for whole foods, and agree that fermentation adds something extra special (I ferment my own foods too). However, thousands of studies demonstrate the importance of EPA and DHA for decreasing inflammation, and it definitely is dose-dependent. So the fact that Green Pastures doesn’t publish the amount of omega-3 suggests to me that the levels are either very inadequate, or very inconsistent across batches. Furthermore, I also have concerns about purity — even wild fish are no longer free from concerns about contamination. If someone wanted to take their omega-3s from a product like that, my suggestion would be to take one of the many omega-3 indexes around to test their blood levels of omega-3. This way, they know exactly if they’re deficient. And if someone is trying to treat a chronic inflammatory condition with omega-3s and aren’t making progress with this cod liver oil, to switch to something that tells them exactly how much omega-3 they’re getting.

  3. says

    P.S. Just noticed your grain-free salmon cakes recipe. I usually use Udi’s bread to make the cakes stick and avoid the use of wheat, but Udi’s has too many ingredients for comfort. Thanks for the coconut flour suggestion!

  4. says

    Great post, we follow you on Facebook and love the content. One thing we also like to mention to customers in our store regarding low quality (Costco, specifically) fish oil is to watch out for anything in the Ethyl Ester form. This is technically NOT fish oil, as fish do not produce ethyl ester. After our own research, and meeting with several companies, we chose Nordic Naturals as the main N3 brand at Everlasting Health Center. We will now be sure to give Green Pastures a look as well. thanks!