September 25, 2009

Fish Oil, Yes--But NOT From Fish

There is quite a lot of evidence suggesting that fish oil, a mixture of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has strong anti-inflammatory properties and may also improve lipid profiles and heart attack risk.

You can read an excellent summary of a review that looked at this data here:

Omega-3 Polyunsaturated Fatty Acids and Cardiovascular Disease Protection (American College of Cardiology CME)

One small area of concern about the research cited is that quite a lot of it was done with a prescription (i.e. expensive, proprietary) form of fish oil called Lovaza made by drug kingpin GlaxoSmithKline. You can read the official Prescribing Information about Lovaza HERE.

Lovaza costs around $100 for 60 1 gm capsules and in the studies cited 4 gram daily doses were used. The fish oil you buy at the pharmacy is about $15 for 200 capsules and you can often find "buy one get one free" offers.

This issue is important because the above review notes that re a major Lovaza study "Other studies, including a recent underpowered OMEGA trial, have not demonstrated such benefits." The explanation could be that Lovaza is worth the obscene price or that GSK used the usual big pharma study design dodges and statistical tricks to skew the results. My guess is the latter.

Subtract the drug company studies, though, and there is still a lot of evidence pointing to fish oil as being helpful in inflammatory contexts. You can read a older full-text review that cites many observational studies HERE.

A very recent study examined the impact of fish oil on gene expression, comparing the effects on genes in human subjects of six month supplementation with fish oil against supplementation with sunflower oil.

Fish-oil supplementation induces antiinflammatory gene expression profiles in human blood mononuclear cells. Bouwens M et al. Am J Clin Nutr 2009 Aug;90(2):415-24. Epub 2009 Jun 10.

The finding of the gene study was that
A+DHA intake resulted in a decreased expression of genes involved in inflammatory- and atherogenic-related pathways, such as nuclear transcription factor kappaB signaling, eicosanoid synthesis, scavenger receptor activity, adipogenesis, and hypoxia signaling.
The dose in the above study was 1.8 g a day of fish oil. It is not mentioned if the study used a branded version.

This suggests that fish oil would be a worthwhile supplement for people with diabetes because heart disease is now known to be an inflammatory condition. Some people with Type 2 also turn out to have autoimmune factors at work in attacking their beta cells.

But as good as fish oil might be for you there is one huge caveat. Thanks to the heedless pollution of our environment by coal burning plants releasing mercury in the air, fish has become an extremely toxic way to get your fish oil.

The data commonly cited about the amount of mercury in fish is between twenty and thirty years old and what little evidence we have the current levels of mercury in fish is far, far higher.

Here is the FDA listing of mercury levels in fish:

FDA Mercury Levels in Commercial Fish and Seafood

Note that the date of most of the mercury concentration data cited for many of the fish is "1990-1994" and for some, like shrimp and mackerel, it is 1978.

I personally know two people who consumed fish several times a week believing in its health benefits who were diagnosed with toxic blood mercury levels by mainstream doctors and given chelation therapy.

In a recent book, Experimental Man, by David Ewing Duncan, one that is otherwise not worth reading, the author ate a fish and then went to the lab and had his blood analyzed for mercury. The reading reported was far higher than what the FDA lists of mercury in that particular fish would suggest.

So this suggests that eating fish is not a good way to get the benefits of fish oil.

Capsules are better, though they may, in fact, contain very small amounts of mercury, the amounts are dramatically lower than that found in fish.

Here is a study that gives you some idea of how much mercury might really be in fish oil capsules. Many are free of it, some of it do have small amounts:

Measurement of Mercury Levels in Concentrated Over-the-Counter Fish Oil Preparations: Is Fish Oil Healthier Than Fish? Stacy E. Foran et al. Archives of Pathology and Laboratory Medicine, Vol. 127, No. 12, pp. 1603–1605.

One VERY important warning. Over the year that I have been buying fish oil capsules, I have found the ingredients of the capsules changing from bottle to bottle within the same brand. So does the origin of the fish oil which may be listed as "sardines" in one bottle and not mentioned in another, suggesting it comes from larger, more mercury-polluted fish. I found this true for several different brands. So when a manufacturer cites test values those values may have been done months before and may be entirely different from results you'd see if the tests were performed now.

Because mercury levels in fish roughly correspond to the size of the fish, you'd do best with fish oil made from very small fish, like sardines. However, small fish taken from highly polluted waters may be more toxic than you'd expect. I also see soy oil increasingly making its way into capsules, a concern for those who have problems with soy proteins. So when you buy your fish oil, examine the label carefully each time.

Another very important point: Buy "Enteric coated" fish oil. Unlike the plain kind, it will not cause you to burp up disgusting bits of fish oil all day.



Anna said...


It has been suggested to me a number of times that fishy burps are sometimes due to a gall bladder that is calcified and not working efficiently. Have you run across any information about that? I am aware that people who have been following low fat diets for many years can often develop gall bladder issues, essentially from from lack of use, which leads to sludge, gall stones, and blockage.

My husband isn't able to tolerate the Costco brand of fish oil, so he takes krill oil. The price has come down quite a bit since krill oil became more available.

Jenny said...


I have not hear that about the gallbladder. I doubt it is true.

I have always gotten terrible fish burps from fish oil, but I have had zero gall bladder problems and was only on a low fat diet once in my life, for 28 days 12 years ago.

ItsTheWooo said...

I've been using purified EPA/DHA from the vitaminshoppe. I figure this gives all the stuff I want (long chain omega 3 fatty acids cultivated from fish) and none of the crap.
This is the brand that the vitaminshoppe sources it from:

country mouse said...

omega3-s give me migraines. bloody f*****g migraines that make me hide in the dark for days. odd thing is, I can't find any documentation on this effect. soy also presents a similar reaction so maybe soy oil is more common than one might think. and NO, I am not willing to experiment with your favorite brand of supplement who ever you are :-) seriously, the pain is just too great to risk it.

Unknown said...

Check out no murcury...Have been taking it for years...

Jenny said...

There is NO way of knowing if a supplement maker's claim is true or not.

There is no regulation of supplements and the only time they get investigated is if a person's death or severe disability looks like it was caused by the supplement.

With the huge profits in the supplement business there is every reason for the supplement companies to lie.

The smaller and crunchier the company, the less reason you have to trust it.

Venkat said...


Thanks for the informative post.

Have you heard of claims that fish oil capsules increase serum Uric acid levels for some at least? I have been consuming Fish Oil capsules for the past 6 months and ever since I started my UA is high. Once I run out of current lot of Fish Oil capsules, I plan to buy and consume Cod Liver oil capsules. I am checking WAPF site for help in identifying correct Cod Liver oil form/brand/type.

Just wanted to share my 2 cents.



Jenny said...


I hadn't heard of fish oil raising uric acid but that doesn't mean they might not. Do you have a gout problem with meats, too?

Venkat said...


I am a vegetarian for religious reasons though I am learning now that being vegetarian is not good for health. So, I do not consume meat other than dairy and egg (though I was told that Egg yolk does increase UA).

Before I started of with Fish oil capsules, UA was 5.5 and now it is 8.0 for last 2 quarters. With all other things being same, since this is peaking - I checked online and came across people complaining this UA increase and gout.



Jenny said...

I just did some googling and it appears that some people find fish oil HELPS with gout pain and that there is evidence that while fish itself worsens gout, the purified oils do not.

It is possible the fish oil you are using is not refined enough.

Betty said...

Hi Jenny,

I just discovered your blog, thank you for the very informative posts...One question I have about taking the fish oil supplements is what about individuals who have fish allergies? My husband has had an extreme allergic reaction to shellfish once, and he is extremely reluctant to take fish oil, despite it's proven benefits...TIA

Jenny said...

People with fish allergies should absolutely NOT use fish oil.

Anonymous said...

I have no gallbladder any more. Some fish oil (and some fish, particularly mackerel which is not absolutely fresh) produces fishy burps, some does not. Make of that what you will.

An important factor appears to be not only the Omega 3 per se but the ratio of that to Omega 6: excess Omega 6 may be the confounder in studies that find differing results.

among others

Unknown said...

You can buy vegan DHA capsules. DHA is one of the omega 3 oils.