So I 'm reading some of the posts on nutrition..... I see a couple of posts listing consumption of grams per day of fish oil.
Problem: what you think you're getting ain't necessarily so..
The second most common component, by mass, of both fresh water and marine fish are oils. THese oils are either saturated and unsaturated fatty acids.
EPA [eicosapentaenoic acid, 20:5(n-3)] and DHA [docosahexaenoic acid, 22:6(n-3)] are long-chain omega-3 polyunsaturated fatty acids (LC omega-3 PUFA) essential in the human diet. The omega-3 PUFA are largely obtained through the diet since humans generally are unable to synthesize them. These are "good essential fatty acids", in that they are converted into prostanoids that counteract inflammation, PGE1 and PGE3.
Marine-derived omega-3 fatty acids have a wide range of potential health benefits, particularly with respect to the prevention of coronary heart disease and rheumatoid arthritis (these are chronic diseases with a underlying etiology of poorly controlled inflammatory response. These omega-3 (n-3) fatty acids also may play a role in modulating or preventing cancer (arachadonate bind sites on the surface of some cancer cells causes them to proliferate) and other disorders (such as chronic migraines, fibromyalgia, and neurological diseases), although further research and trials are required. Omega-3 fatty acids may be also beneficial for infant brain and retina function and development.
Omega-3 fatty acids increase the arachidonic acid content of liver cholesterol ester and plasma triacylglycerol fractions in the rat. Garg ML, Wierzbicki AA, Thomson AB, Clandinin MT. Biochem J. 1989 Jul 1;261(1):11-5.
Now the bad news...another quite common component of these fish oils are a group of fatty acids called acachondonates, abreviated as AA [arachidonic acid, 20:4(n-6)]. This is an omega-6 PUFA which is a precursor of prostaglandins (which modulate hormone activity) and other eicosanoids (C20 physiologically active compounds). Prostaglandins are synthesized from arachadonates in humans in a three-step reaction. The reaction product, PGE2 (or prostaglandin E2) is an inflammatory agent.
Here's the rationale for my advisiing moderation in consumption of fish oils:
(1) all essential fatty acids compete for access to the same three converting enzymes that lead to the production of both beneficial and detrimental prostaglandins. Since the relative content of the good essential fatty acids (n-3s) is higher in less oily fish (that is, the relative mass of n-3 to n-6 fatty acids is less than 1:1 or 50:50), less oily fish will produce less of an inflammatory potential than more oily fish. Guess what the industry uses?? Oily fish (fish oils are a by-product of fish processing).
(2) your body can only process so much essential fatty acids that are taken in thru diet or as a supplement. If you take a lot of a fish oil supplement, and the n-3 omega's are outmassed by the n-6s and n-9s (as in the case of oily marine fish that are the source of the fish oil) , and there is also a considerable component of AAs, then the supposed benefits are outmassed, in a very straightforward competition.
(3) the remaining essential fatty acids can be stored, temporarily, in cell membranes, but these are easily oxidized and used as an energy source. Arachadonates appear to be stored and released, which suggests that their detrimental effects may linger for days after consumption.
(4) fish oils are a naturally occuring "phase" within tissue in which hydrophobic contaminants, such as pesticides and the preservatives that were forumated with those pesticides (PCBs) bioaccumulate. These toxic contaminants are well-known to accumulate in many oily fish; fish consumption advisories have been documented in the press and verfied in a considerable body of scientific literature. These contaminants will also bioaccumulate in human fatty tissues (including fat deposits, liver and brain) that consume fish oils.
Therefore, excessive consumption of these fish oils may lead to unwanted effects.
As the most prominent component of marine fish, complete proteins, is also a desirable nutritive source for strength conditioning, it is advisable to consider *extreme* moderation in consumption of these concentrated oil supplements, regardless of the source (flax seed is common source of vegetable EFAs, with a mass ratio of approx 1:1 n-3s to n-6s).
It would more sensible, given the facts presented above, to add fish as a primary protein source no more than 3-4 times per week (due to the presence of heavy metals, pesticides, chlorinated solvents, and other carcinogens and that also bioaccumlate in fish tissue).
Food for thought.
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In response to a reply to this post, a partial listing of applicable references is supplied:
Competition among fatty acids for prostanoid biosynthesis:
http://www.westonaprice.org/know_your_fats/tripping.html
http://lansbury.bwh.harvard.edu/fish_oil_reviews.htm
http://www.asthmaworld.org/OMEGA3.htm
Omega-3 fatty acids increase the arachidonic acid content of liver cholesterol ester and plasma triacylglycerol fractions in the rat. Garg ML, Wierzbicki AA, Thomson AB, Clandinin MT. Biochem J. 1989 Jul 1;261(1):11-5.
Essential fatty acids: content of in various foods: http://www.annecollins.com/dietary-fat/omega-3-efa-6-chart.htm
Fatty acid content in milk (ref to another post which also describes fatty acids effects in cheese): http://www.fao.org/ag/AGA/AGAP/FRG/AFRIS/DATA/335.htm
Fish oils, fatty acids, and inflammatory response:
http://www.findarticles.com/g2603/0003/2603000366/p1/article.jhtml
Fish oils and pesticides:
http://www.udoerasmus.com/articles/press/2002_06_fishoil.htm
http://www.berkeleywellness.com/html/fw/fwNut05Fish.html
http://www.pan-uk.org/pestnews/Pn31/pn31p19c.htm
http://www.drweil.com/app/cda/drw_cda.html-command=TodayQA-questionId=93664 |
the fats that cause inflammation.