Review of Kirkland Fish Oil

bottle of Kirkland fish oils Super Concentrate Omega-3 1150 mg

Is Costco’s Kirkland fish oil a good fish oil supplement?

As you already know, Costco is a popular warehouse membership club that has dozens of locations all over the world.

One of the benefits of membership is you can get exclusive products made only for Costco.  The product line is called Kirkland.

Costco sells two different versions of their fish oil:

  1. Kirkland Natural Signature Omega 3 Fish Oil
  2. Kirkland Signature Enteric-coated One-a-day Omega 3 Concentrate

The fish oil supplements are a popular segment of the nutritional supplement industry. Experts predict that the global fish oil market will exceed over $3 billion by 2025.

And it’s no surprise that Costco would want to get in on this lucrative and popular nutritional segment with their own branded product.

When it comes to buying fish oils, you may find it tricky trying to find your way around. You want to choose the best product for your health, but which one do you get?

The fact is, not all fish oils are the same. The industry isn’t completed regulated and even some of those big name brand products have been found to not contain what’s listed on the label or had unwanted mercury or other contaminants.

This review will focus on:

  • what type of fish Costco uses to make their fish oils
  • what’s the overall purity and quality
  • what are the omega 3 fatty acid concentrations (EPA and DHA)
  • the differences between Natural Signature and Signature Enteric-coated versions
  • what are average customer reviews of this product
  • the average cost per dosage of each product

What are They Made From?

Both versions of the Kirkland fish oil product line are made from sardines and anchovies.

One of the benefits of using smaller fish, like sardines and anchovies, is that they naturally come with a lower risk of exposure to mercury and other contaminants, compared to much larger-sized fish.

Fish can get mercury in their bodies from eating other fish.  Smaller-sized fish are less likely to eat fish bigger than themselves, so they’ll tend to have naturally lower levels of mercury, compared to larger-sized fish that eat bigger fish.

close-up of pile of sardines and anchovies

Sardines contain higher amounts of EPA and DHA

This is supported by a report published by the FDA, called a Comparison of Mercury Levels in Commercial Fish. Their report showed that sardines and anchovies contained over 50 times less mercury than larger-sized fish, such as fresh tuna and mackerel.

Their research found that sardines contained an average mercury concentration of 0.013 ppm (parts per million) and anchovies was about 0.016 ppm.,Larger species of fish, such as tuna and mackerel contain 0.689 ppm and 0.73 ppm, respectively.

Verdict: Costco’s choice to use smaller fish (sardines and anchovies) means you’ll have a lower risk of exposure to mercury and other other contaminants.

Avoid Omega 3 Oils Made from “Farm-Raised” Fish

Costco claims to use only wild-caught fish to make their oil.

The advantage of using wild fish, compared to farm-raised fish, it that they contain naturally higher amounts of omega 3 fatty acids. This is because fish caught in the wild live off of a natural diet of eating only other fish, algae or plankton find in the sea. All of these food sources contain a rich source of omega 3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

The problem with eating farm-raised fish is that they’re usually fed a diet of food pellets (and even antibiotics). This is an unnatural diet and it can lower the quality and amount of healthy fats found in the fatty tissue of the fish.  This is similar to choosing a steak that comes from a grass-fed cow, or one that comes from a cow that was raised an factory farm.

The Environmental Working Group (EWG) has also expressed concerns about eating farmed fish. Independent laboratory tests have shown that the average, farmed-raised salmon have 16 times the dioxin-like polychlorinated biphenyls (PCBs) at levels that raise health concerns.

Made from Molecular-Distilled Fish Oil:

Kirkland fish oils are made through a process called molecular-distillation. This modern refining method is commonly used to create pharmacuetical-grade fish oils. The process uses a vacuum and various temperatures that help to ‘distill’ the oil and other ingredients at different stages. The result is a highly concentrated product that has higher levels of omega 3 fatty acids, with almost completely undetectable traces of mercury, PCB’s and other contaminants. Costco claims that the mercury levels for their products are undetectable at less than 0.1 parts per billion.

Kirkland Fish Oils Comes in Two Forms:

1. Kirkland Natural Signature Omega 3 Fish Oil
– It’s made from anchovies and sardines.
-Ingredients include: Fish Oil Concentrate, Gelatin, Glycerin, Water, Tocopherol.
– Each bottle provides 400 soft gels of 1000 mg providing 300 mg of EPA and DHA.
– Provides a 30% omega 3 fatty acid concentration per soft gel.
– Suggested Retail Cost is $9.99 per bottle.
– Recommended dosage is 3 soft gels per day at 9 cents/day.

2. Kirkland Signature Enteric-Coated One-a-Day Omega 3 Fish Oil Concentrate
– Also made from anchovies and sardines.
– Comes with an Enteric Coating which helps prevent fishy aftertaste by delaying absorption in the stomach.
– Ingredients include: Fish Oil Concentrate, Gelatin (non-bovine), Glycerin, Water, Vanillin, Tocopherol.
The Enteric Coatings also have two (2) different formulations, depending on which country you’re from:
  • The USA Costco website says it may contain Hydroxypropyl Methylcellulose Phthalate, Stearic Acid, Methacrylic Acid Copolymer, Oleic Acid, Ethylcellulose, Sodium Alginate, , Medium Chain Triglyceride, Triacetin, Ammonium Hydroxide, Polyethylene Glycol
  • The Canadian Costco version contains bovine gelatin, glycerine, purified water, pectin, sorbital, natural tocopherols
– Each bottle provides 180 soft gels with each 1200 mg soft gel containing 410 mg. of EPA and 274 mg. of DHA.
– Provides a 57% omega 3 concentration per soft gel.
– Suggested Retail Cost is $14.99 per bottle.
– Recommended dosage is 1 soft gel per day at 8 cents/day.

Differences Between Natural Signature and Enteric-Coated One-a-Day

As you can see from the above, there are some slight differences in the ingredients used to make Kirkland Natural Signature and the Kirkland Signature Enteric-coated One-a Day products.  There is also a slight difference in the enteric-coated ingredients used in products sold in the USA vs Canada.

There are many pros and cons to using enteric-coated fish oils and it will most likely come down to your own personal decision. The biggest advantage is they may help improve digestion and absorption of the oil. However, some people are unable to swallow soft gels or the capsules are only available in a certain size.

We compared the Kirkland Enteric and Non-Coated fish oils on a cost-per-basis.

Based on our calculations (and latest prices at press time) we found:

Enteric-Coated Softgels:

  • available in 1000 mg. soft gels
  • enteric-coated product will last 180 days at 8 cents/day
  • one bottle will last 47 days longer than non-coated
  • you get a higher concentration of EPA and DHA per softgel (57% vs 30%)

Non-Coated Softgels:

  • also available in 1000 mg. soft gels
  • non-enteric coating will last 133 days at 9 cents/day.
  • doesn’t come with the extra ingredients used to make the enteric coating

size of fish oil soft gel

Size of Kirkland Fish Oil Soft Gel

As  you can see in the photo above, the capsules are about 1 inch long and 3/8th inches wide.

The Reviews are In! Consumers Like Kirkland Fish Oils:

pouring open bottle of kirkland fish oil soft gels into open palm

This product appears to be fairly popular with customers.  At press time, the online reviews on the site showed that about 68% of  customers gave these products 4.5 out of 5 stars and 83% of the total reviews gave at least a 4 out of 5 rating.

And reviews at one of the largest online retailers also appear favorable. Reviews at showed that about 89% of customers gave this product at least a 4 out of 5 star review.


Kirkland fish oils appear to be a high quality product, at very affordable prices with many positive customer reviews.

If you’re a health-conscious consumer on a budget, this may be product that’ll meet your needs.

When we compared Kirkland fish oils to other big-box retail brands, we found some similarities in quality, dosages and prices.

For example, Walmart’s private label brand Spring Valley Fish Oil, was fairly close in value and quality to Costco’s fish oil when we compared the omega 3 fatty acid concentrations and price per dosage.

You can pick up this product at your local Costco store or search on-line for Kirkland Signature Omega-3 Fish Oil Concentrate.

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