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The Fish vs. Fish Oil Smackdown


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Update: I now recommend Extra Virgin Cod Liver Oil from Rosita as my preferred cod liver oil product. For more information, read this article. You can purchase EVCLO here.

So far in this series we’ve looked at why fish is superior to plant-based sources of omega-3. We’ve examined the importance of reducing consumption of omega-6 fats. We’ve considered how much omega-3 is needed to support health and treat disease. And we’ve revealed that concerns about the safety of fish consumption have been overblown, and that eating fish regularly is not only safe, but incredibly beneficial.

In this article we’re going to compare fish with fish oil as a means of meeting our omega-3 needs, and for overall health and wellness. The comparison will be based on the following criteria: nutrient content, potency, absorption, cost and environmental impact.

Fish oil has become wildly popular in the last few years, as people increasingly understand the importance of omega-3 in the diet. However, part of the reason for fish oil’s popularity is related to concerns about the safety of eating whole fish – concerns that we now know are unfounded.

With this in mind, let’s see whether whole fish or fish oil are the best choice for most people.

Nutrient content

Fish: contain not only EPA and DHA, but also vitamin D, selenium, protein, co-factors and a more complete fatty acid profile than fish oil. Selenium, in particular, is important because it protects against mercury toxicity. Vitamin D protects against nearly every modern disease plaguing us today. A 6 oz. portion of wild salmon contains 1,700 IU of D, which is difficult to obtain in that amount from other dietary sources.

Fish oil: most oils contain only EPA and DHA, although salmon and cod liver oil also contain moderate amounts of vitamin D. Fish oil has a more limited fatty acid profile than whole fish, and doesn’t contain selenium.

Potency (levels of EPA & DHA)

Fish: a 6 oz. portion of wild salmon contains 883 mg of EPA and 1,111 mg of DHA. 2-3 servings a week of salmon, combined with a low intake on omega-6, would be adequate for most people.

Fish oil: this is where fish oil may have an advantage over fish.

Because it is molecularly distilled and purified, fish oil can have high concentrations of DHA and EPA. 6 capsules of Jarrow Max DHA would provide 1.5g/day of DHA, a level that would be difficult to obtain from eating fish.

You’d have to eat approximately 8.5 ounces of wild salmon every day to obtain that much DHA.


Here’s where things get a bit tricky. I talked about potency above, and mentioned the levels of EPA and DHA in both fish and fish oil. However, those levels mean very little unless we consider how well they’re absorbed.

Several studies indicate that fish oil supplementation is not as effective as epidemiological evidence on the benefits of fish consumption suggest it would be. It appears that the presence of other fats in the fish activates processes required to absorb the EPA and DHA properly. This explains why the EPA and DHA are better absorbed from eating whole fish than from taking fish oil.

In one study comparing the effects of fish and fish oil, researchers found that levels of DHA after 6 weeks of salmon consumption were nine times higher than after fish oil administration.

The authors hypothesized that the configuration of fatty acids in whole fish is familiar to our body and thus easier to absorb. Conversely, the fish oil alone doesn’t adequately activate the process of fat absorption required to assimilate the fatty acids.

Another study confirmed this by demonstrating that fish oil is absorbed much better in the presence of a high-fat meal. They found that the content of n-3 fatty acids in the body tissues rose dramatically when the fish oil was taken along with 12g of olive oil.

We can draw two conclusions from these studies:

  1. EPA, and especially DHA, is much better absorbed from fish than fish oil. The effect may be as great as nine-fold. This means that we would need nine times less DHA from fish to obtain the same amount of DHA from fish oil. Put another way, we’d need nine times more DHA from fish oil to obtain the same amount of DHA from fish. So, using the 6 oz. portion of salmon as an example, with 1.1g of DHA, we would need to take 9.9g of DHA from fish oil – roughly 36 capsules/day of the Jarrow Max DHA – to obtain the same amount of DHA we’d get from the salmon. That’s a lot of fish oil!
  2. On the other hand, taking fish oil capsules with a high-fat meal can greatly improve their absorption, to the point where they may be on par with whole fish. (I say “may be” because the scientific literature is mixed on this.) This is likely due to the effect described above, where the presence of other fats activates the body’s fat absorption mechanisms.

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This is also tricky to compare, since prices and availability of fish vary regionally. A straight comparison of the cost of DHA obtained from fish and fish oil also ignores other important factors, which we’ve already discussed above, such as the presence of other nutrients and the differences in absorption.

Let’s assume for the sake of comparison that fish oil is taken with a high-fat meal to improve absorption and that absorption rates of EPA and DHA are roughly similar between the two. Let’s assume that wild salmon is available for $13/lb. (I know it is much less in some areas, and much more in others).

Let’s assume also that we’re shooting for a daily intake of 500 mg of DHA.

To obtain this amount of DHA from salmon, you’d have to eat just over one pound per week (19 ounces). That would cost you $15.45.

To obtain this amount of DHA from Jarrow Max DHA, you’d have to take 2 capsules per day. Assuming you bought a bottle of 180 capsules from Vitacost for $14.70, you’d pay just $1.14 for the same amount of DHA.

However, you’d have to consider the following caveats:

  1. It’s uncertain whether, even with a high fat meal, you’d be absorbing the same amount of DHA from the fish oil as you would from the salmon
  2. The salmon has large amounts of protein, selenium, vitamin D and other fatty-acids and co-factors that the Jarrow fish oil doesn’t have
  3. Other oily fish that are significantly cheaper than salmon, such as sardines and mackerel, are also very high in EPA and DHA.

Environmental impact

Overfishing and fish farming have already seriously damaged the health of marine ecosystems, and threaten to do even more damage if fish and fish oil consumption increases.

Much has been written about this elsewhere. Charles Clover’s The End of the Line: How Overfishing is Changing the World and What We Eat provides a particularly astute (and scary) analysis of the impacts of current methods of fishing on global ecosystems.

In short, I believe the most responsible choice we can make is to limit the fish we eat to those certified by groups like the Marine Stewardship Council (MSC).

However, even those groups are not infallible. Recently concerns have been raised over MSC’s decision to certify a salmon fishery in British Columbia where the salmon population is declining rapidly. Environmentalists and scientists have protested the decision, but the MSC seems to have moved ahead regardless.

Unfortunately it’s not a cut and dry issue, and those who are interested in eating fish harvested in a sustainable matter will have to do their own research and stay abreast of changing policies and practices.

In general, though, most environmentalists and scientists support the MSC certification. MSC has a list of fish they consider safe to eat on their website, which you can refer to.

MSC also has a certification label (pictured below) they provide to vendors of MSC-certified fish that you can look for when you’re shopping.

The sustainability of fish oil production is even more difficult to gauge. Some oils are produced as a byproduct of fish harvesting, and manufacturers claim that they are simply making use of something that would normally be discarded. While this is certainly better than harvesting fish solely for their oil, it still supports harmful fishing practices.

The safest bet is to only use fish oil that is made from fish that are certified by MSF or a similar organization, such as the Environmental Defense Fund. Vital Choice Wild Salmon Oil is one example, as is Jarrow Max DHA (which is made from anchovies and sardines, both of which are generally regarded as safe to eat from an environmental standpoint).

The verdict

The question of whether fish or fish oil is a better choice is complex and depends upon several different factors. These include whether DHA is needed for maintenance or therapeutic effect, access to sustainability caught wild fish, financial considerations, and the presence of other nutrients in fish.

For those who are generally healthy and want to stay that way, I think reducing omega-6 consumption and eating a moderate amount of oily fish (2-3 6 oz. portions per week) is the best choice. This will get you plenty of EPA & DHA along with high quality protein, selenium and vitamin D. If wild salmon is out of your price range, mackerel and sardines are both high in EPA and DHA and certified by the MSC as safe to eat.

For those who have a chronic, inflammatory condition such as cardiovascular disease or an autoimmune disorder, I would recommend a combination of whole fish (perhaps the same 2-3 6 oz. portions per week) along with a high quality fish oil. This ensures that you are getting the benefits of whole fish along with the added therapeutic effect of higher doses of DHA and EPA. Somewhere around 1.5g per day of DHA would be a good therapeutic dose, which would mean taking 1g/day of DHA in fish oil capsules in addition to the three 6 oz. portions of oily fish.

In the next and final article of this series, I’ll discuss the criteria for choosing a fish oil and make recommendations based on those criteria and clinical experience.

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Join the conversation

  1. Hi Chris,

    Loved the article. One question, why only 2-3 servings of wild fish per week? I love sardines (with skin and bones and some organs) from Wild Planet. I have been Primal for 9 years now and after comparing nutritional profiles of different whole food sources of protein and fat, I found that I prefer to eat sardines over grassfed beef or even eggs. So what about eating about 5-6 large servings of sardines or wild caught salmon per week?

  2. The author goes on about 2 to 3 helpings of salmon every week. Does he not realize such a suggestion is out of the reach of most people with salmon over $27NZ a kilo !!!!!!!!!! Also we have been indoctrinated to believe a lot of fish have excessive mercury content.

  3. If anyone of average intelligence takes the time to read Ray Peats analysis @ raypeat.com/articles-the great fish oil experiment-it gives good science data to consider fish oil Toxic