While the media touts fish as a health food, I've been preaching otherwise for some time now. Besides the Omega-3 fatty acids found in most fish, there's really no benefit to eating it, although there are plenty of hazards: mercury, PCB's (Polychlorinated Biphenals), cholesterol content (the same as red meat), homocysteine levels, Heterocyclic Amines, and of course, fish has no fiber.
The one beneficial compound in fish - Omega 3's - are found throughout plant foods such as nuts, flaxseed and other seeds, legumes, whole grains and fatty fruit like avocados.
But wait, just in case you still weren't convinced, there's a new study published online in the European Journal of Heart Failure (2009;11:922-928) that contradicts the belief that fish prevents heart disease. Researchers studied over 5,000 men and women (who lived in the Netherlands) for over 11 years and compared episodes of heart failure between those who consumed the most fish and those consumed the least. Guess what? They found NO DIFFERENCE. In fact, in their own words, the author of the study concluded: "Our findings do not support a major role for fish intake in the prevention of heart failure."
Wow. Hope this makes headlines too.
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This study appears to be a retrospective case control study, so although large, there are inherent flaws in its design. Also, this study is examining only one health outcome--heart failure. There are likely other outcomes related to heart disease for which fish consumption may have a positive impact, but were not evaluated.
A single study often doesn't tell us much. It's more revealing to look at a body of published evidence to identify trends in particular outcomes, both positive and negative.
:)
A note about the author of this post's statement on the sources of omega-3s. The benefits arising from plant-sourced short-chain fats and LCPUFAs sourced from fish are very different. Indeed most of the benefits of omega-3s are attributed to omega-3s EPA and DHA found in oily fish. These long-chain fats are converted via enzyme elongation reactions to beneficial eicosanoids which regulate inflammation, immune function as well as platelet aggregation. In other words, you wouldn't derive the same benefits from something like flaxseed, of which less than 8% is converted to EPA, and negligible amounts to eicosanoids.
There is a plethora of information on this on the web, including here:
http://igennus-hn.com/fat-facts/omega-3-epa-fish-oil-flaxseed-oil-hemp-oil-benefits/
Of course, short-chain fats as you mention do have their own benefits, and are an important part of a healthy diet - but let's not confuse the differences between the various types!
Mina.
Igennus Healthcare Nutrition
I do agree that we shouldn't make decisions or declarations based on one study, but rather an entire body of evidence. Let me share with you why I believe the study quoted here is important:
This study is part of a very long, extensive, famous study called The Rotterdam Study in the Netherlands. It is not a retrospective study, but a prospective cohort study, which means there is much less room for bias than most studies. These types of studies are considered "gold" in scientific circles due to their lack of inherent bias.
By design, a study cannot scrutinize more than one outcome - in this case, it is heart failure. I'm not sure what is more important than that, but if this very meticulous study happens to find that fish doesn't have a protective effect on heart disease, the public needs to know.
As far as the "body of evidence" that fish does have a protective effect on heart disease, I believe that because of the DHA & EPA fats (commonly known as Omega-3 fatty acids), fish seems to protect against heart failure when compared to other meats, since fish is the only meat naturally containing these fats. So in many instances, people who eat more fish will be less at risk for heart failure than people who eat red meat or poultry.
Yet when we simply compare people who eat the most fish to those who eat the least, as in this study, we may see something different altogether. In this case I believe fish didn't show a protective effect due to the detrimental compounds it contains (mercury, PCB's, cholesterol, homocysteine, Heterocyclic Amines, etc.)
As someone who is not selling anything (like fish oil capsules), I think I personally have less bias about this article as well.
Typically the gold standard in the medical community is the randomized, controlled trial, so although results from a prospective cohort design are valuable and contribute to the overall body of evidence, they still have inherent bias due to lack of randomization.
The study does mention that there was a positive trend (though not significant) towards protection from cardiac failure in a subpopulation of diabetics, which may be important.
Also, the type of fish was not evaluated, so it can be assumed that a variety of fish was consumed, including larger species of fish that contain higher heavy metal content. There may be protective effects observed in species in which heavy metal content is less.
Also, the study evaluated a geriatric population over 11 years. The effects of fish consumption beginning at an earlier age are uncertain, and could be positive.
According to the authors, there has been on only one other large prospective cohort study (>4000 patients, age 65 yrs and older, f/u of 12 years) evaluating fish consumption and heart failure and results from this study were positive and demonstrated statistical significance in terms of protection from heart failure.
It's safe to say based on these two trials with conflicting results that the jury is still out. Until there is a greater body of evidence, including RCTs, the effects of fish consumption on heart failure are unclear.
http://overfishing.org/
http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/HTML/peril_overfishing.html