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What to Look for in a Good Quality Fish Oil

woman taking a fish oil supplement

One of the most frequent questions I get as a certified nutritionist is, “what is a good fish oil to buy?” Don’t feel bad if you are also wondering what and how to figure this out. The nutritional supplement world is confusing even to healthcare professionals!

Let’s dig into the details of what fish oil is, why you should take it, and mostly – how the heck to choose a good one!

What Does Fish Oil Do?

Fish oil is basically the fatty oil taken from fish and purified to remove everything except the beneficial Omega 3 fats found in fish. Studies show that consuming adequate amounts of Omega 3s may help fight depression and anxiety, improve eye health, promote brain health and growth in pregnancy and early childhood, improve risk factors for heart disease, reduce symptoms of ADHD in children, fight inflammation, improve mental disorders, and so much more. (See all the supporting studies linked to these benefits here).

Omega 3 fatty acids found in fish and other marine and land animals are considered essential fatty acids, which means that we cannot manufacture them ourselves, we need to obtain them in our diets. This is incredibly important for brain development in utero and young children. Research has repeatedly linked low levels of the omega-3 fatty acid DHA to neurodevelopmental disorders including autism and ADHD. This is why most Obstetricians are recommending that pregnant women take DHA supplements. Ideally, a couple would be taking Omega 3 supplements preconception.

What are the Benefits of Fish Oil?

Can’t I just take plant based Omega 3s?

Well, no. Plant sources DO contain Omega 3s, but they are in the form ALA. The human body is incredibly inefficient at converting ALA into DHA and EPA, which are the forms that the body can use.

Why do I need EPA + DHA?

Omega 3 fats in the EPA and DHA forms are needed by the body to use as cell membrane components. These super flexible essential fats act as gatekeepers to each cell membrane, regulating nutrients and waste product entry and exit.

If the body doesn’t have sufficient intake of these specific Omega 3 fats, it will use other fats like trans fats and saturated fats. Unfortunately, saturated fats, trans fats, and other non-Omega-3 fats are more stiff in nature and can’t act as good gatekeepers to the cell.

Cell membranes with poor levels of Omega 3 fats are less responsive to hormones, including insulin sensitivity, and can’t shuttle nutrients in and out as effectively. Think of it like this: Imagine if your cell membranes were like a house, and the windows and doors were the way in and out of the cell. If you have a poor diet low in Omega 3s and high in other fats then your “house” will have doors and windows that are barred shut.

Does Fish Oil Help Concussions?

Katie recently wrote about her experience when her son suffered a concussion. She learned that not only are Omega 3’s essential in healing the brain they can help you strengthen your overall brain health which in turn could prevent concussions.

Can I Just Eat Fish?

Yes! If you are consuming roughly 2-3 servings of fatty fish per week (as recommended by The American Heart Association) like salmon, mackerel, herring, sardines, and tuna you may not need to supplement. However, I find most people are not eating this much fish and they are consuming far too many Omega 6 fats from vegetable oils thus making their body skewed towards a pro-inflammatory state. Therefore, fish oil can supplement a low-fish diet and rebalance a person’s Omega 3 to Omega 6 ratio.

RELATED: Finding Sustainable Seafood.

Holding a fish oil pill.

How to Buy a “Good” Fish Oil Supplement

Avoid contaminants in Fish Oil

Many fish species are known to contain contaminants like mercury, PCBs, and dioxins. However, when you eat fish you are also consuming nutrients like selenium that bond to heavy metals like mercury and make it unavailable for absorption into your tissues.

When you buy fish oil, protective nutrients like selenium have been removed. So, you need to make sure that the other contaminants have either been mostly or completely removed as well.

How do you know this? Read on…

Look for quality assurance from trusted 3rd party testing

USP Mark

Governmental fish oil quality standards do not exist in the United States, but all dietary supplements are regulated by the FDA through the DSHEA act of 1994 and The United States Pharmacopeia (USP). For products carrying the USP Verified MarkUSP has tested and verified ingredients, potency, and manufacturing processes.

Above and beyond the USP Mark

Just because a fish oil bottle doesn’t show the USP Verified Mark doesn’t mean it’s bad! Many reputable fish oil companies will go above and beyond the USP mark and abide by more stringent and voluntary standards. These standards also guarantee quality products by setting maximum allowances on peroxides, heavy metals, dioxins, and PCBs, and are often far lower than the limits set by USP.

List of 3rd party certifications to look for:

(This is not all-inclusive but lists the most common certifiers.)

bag of fish oil supplements

It is interesting to note that The International Fish Oil Standards (IFOS) Program is the only third-party testing and certification program for fish oils. IFOS sets the world’s highest standards for purity, potency, and freshness. Since 2015, they’ve even started testing for radiation levels after the Fukushima disaster. They don’t make fish oil, they only test it and publish the results free to the public. You can see if your fish oil passes the stringent testing here.

Certificate of Analysis for Fish Oil

As I mentioned before, there is no quality standard in the USA for fish oil. That’s why if you are questioning the legitimacy of a nutrition label and the contents of the supplement, it is essential that you ask for something called a Certificate of Analysis (COA) from the manufacturer before you buy their product. A COA is an analysis performed by an independent lab to measure the ingredients of a product and confirm whether it lives up to the claims made by the manufacturer. Most companies are happy to provide this when asked.

For example, when I looked up the COA for Nordic Naturals, it is clearly provided right here so the consumer can simply enter the lot number and get the results.

Interestingly, when I called Kirkland to get a COA for their fish oil they said they don’t give that out. I was referred to their website where it declares the “purity levels for PCBs, dioxins, furans, and mercury are below .09 ppm, 2ppt WHO TEQs and 0.1 ppm respectively.” Umm, great but consumers have a right to know EXACTLY how much mercury is in their fish oil, even if it is parts per gazillion.

It’s a red flag when a supplement company is withholding of information. It’s always best to stick with open and upfront companies who are happy to provide full transparency.

Do you see how confusing it can all be? To ease any fish oil quality concerns, a powerful combination of quality 3rd party testing and a COA can help assure the potency and purity of a fish oil product. In my opinion, getting an IFOS 5-star review is enough assurance!


Fish oil supplements should be made and packaged only in facilities that have been certified in Current Good Manufacturing Practices (or CGMPs), which are strictly monitored for safety.

Can I Test Purity by Freezing Fish Oil Capsules?

No, this is a myth seemingly propagated by certain supplement companies. Good quality fish oil supplements can look cloudy when frozen.


Try to buy fish oil that is certified by the MSC, the Environmental Defense Fund or a similar organization. Small fish with short lifespans tend to be more sustainable.

Shelf life of Fish Oil – shorter is better

2 years or less is best.

Is Liquid Fish Oil Better than FishOil Capsules or Vice Versa?

Not really. If you are buying a good quality fish oil, then it is more a matter of personal preference.

The advantage to taking liquid is that you can get a higher dose of Omega 3s without having to swallow too many capsules. The cons to liquid fish oil are that some people have issues with the smell, taste or consistency. An open bottle can also oxidize (go rancid) faster so make sure you use it consistently and in a timely manner.

The advantage of taking the capsules is no smell or taste. Some capsules are even enteric coated to help keep the capsule from being dissolved until it reaches the small intestines. This is common in fish oil capsules, as it often prevents fish burps. However, it can also mask the foul smell of rancid fish oil. If you take omega-3 capsules, it may be a good idea to open one from time to time and smell it in order to make sure it hasn’t gone rancid. The disadvantage of capsules is usually a higher cost per serving.

Potency & Dose of Fish Oil

A standard daily dose of EPA + DHA is around 1,000-2,000 mg. A therapeutic dose is usually around 2,000 mg of EPA + DHA or more.

How to read the label – potency matters

As you can see in the infographic below, it’s important to read the label on the back of the bottle because the front can be deceiving.

basket of fish oil supplements

Front Label – Says 1000 mg fish oil. You think, great! 1-2 capsules per day for a standard dose. WRONG!

Back label – Here is where we see the truth. If you stopped reading at the front label you would never know that the back label says you are only getting 500 mg of Omega 3s in TWO capsules. That is only 25% of what you thought you were getting (a 2,000 mg dose). To get 1,000-2,000 mg of EPA + DHA you would have to take 4-8 capsules per day. I know, not likely to happen.

How to read a fish oil label


When buying any supplement, but especially fish oil, ask yourself these questions in order to ensure that you are buying a good quality nutritional supplement:

  • Has an independent scientific authority verified product purity and quality, providing a third-party seal of approval on the package?
  • Has it been tested for the absence of harmful levels of known, potential contaminants?
  • Was it produced at a facility that meets or exceeds government and industry standards for good manufacturing practices (GMPs)?
  • Does the label make claims that seem too good to be true?

If you can answer ‘yes’ to the first 3 questions and ‘no’ to the last one, then you are probably getting good quality stuff.

A quick reference

A short list of fish oil companies that are commonly found, meet all the requirements and standards to be considered “good quality”, AND provide a decent potency of fish oil/capsule.

Keep in mind, this is not an all-inclusive list! In fact, it’s very short and I’m sure there are other great fish oil supplements that are not listed here. Once again, do your own research to be sure!

Disclaimer: Before starting any new diet and exercise program please check with your doctor and clear any exercise and/or diet changes with them. I am not a doctor or registered dietitian. The information presented herein is not presented with the intention of diagnosing or treating any disease or condition. This information is for educational purposes only. No responsibility is assumed by the author nor anyone connected with this website for the use of this information and no guarantees of any kind are made for the performance or effectiveness of the recommendations provided.

Unless otherwise credited, photos are owned by the author or used with a license from Canva or Deposit Photos.

14 thoughts on “What to Look for in a Good Quality Fish Oil”

    1. Carolyn @ Kitchen Stewardship

      There’s a list of recommendations at the bottom of this post. Which is best for you will depend on your needs and budget. 🙂

  1. Please help! Fish oil or Cod Liver oil? Which is better?
    Also, the links in the article all led me to capsules. Are the same companies’ liquids also good/safe?

    1. Victor Cozzetto

      I would only use FCLO from Green Pasture. I am very surprised by this article, as I would disagree with the viability of any fish oil supplements. FCLO is the only one that will resist oxidation (rancidity) long-term. In fact, the ability of FCLO to avoid oxidation is quite remarkable. Testing will show that other CLO and fish oil products will go rancid quite quickly, losing their omega 3 value, along with other nutrients. Not to mention that consuming rancid oils is not good for you. Search for the scientific testing and you will see what I am talking about.

  2. I’ve wanted to start fish oils for years but I’ve tested positive for Salmon and Tuna allergies so I’ve never known if I can take the supplements. I have never been a fish fan and since my dad and his dad are both allergic the doctor testing believes it’s an inherited allergy not an over exposure. They told me to avoid all fish in that family. I didn’t think to ask them years ago when I was tested. Can a person with salmon allergies take fish oil?

    1. I would assume that you may have a reaction as it’s from the same thing. However, I suggest searching for a B. I. E. Practitioner in your area. (bio intolerance elimination) My family and friends have had help and elimination of food allergies and it has been safe. One was a severe shellfish allergy. You aren’t exposed to any harmful substances.

  3. I wanted to mention Rosita’s as another high quality fish oil. They offer both capsules and liquid and I’ve found the liquid to be very mild tasting. It’s expensive but the quality is there and the health benefits are top notch!

  4. Kirkland brands are made by outside vendors and are kept confidential. NatureMade does a majority of their health supplements. They may do the fish oil as well. Try calling them.

  5. This is so helpful and informative – and so important to make sure we know what we’re investing in and what we’re wctuslly getting. Shaklee is our fish out of choice for purity, potency, and efficacy 🙂


    I take Nutrilite Heart Health Omega. I have found that Nutrilite is the largest vitamin and supplement company in the world and that they have the most scientific research and the best quality control of any other company. This product has 30 IU of vitamin E, 1200 mg of EPA and 600 mg of DHA.

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