Fish Oil – Essential?

I’ve not posted anything for a while, as I’ve bitten-off a number of complex areas to research and it’s taking longer than I thought!  I am also reading a very easy-going introduction to Epigenetics by Nessa Carey, by way of introducing myself to a topic that has really emerged in the years since I read Biology.  It’s a fascinating field and her book elucidates the common mechanisms that control DNA expression, for example, the methylation of the base cytosine to 5-methylcytosine (a process which switches the expression of the DNA off) , can be replicated and passed from one generation to the next.  Thus we are not just born of our parents, but of the environmental and nutritional milieu they inhabited and how that affected their DNA.

I was also going to post something about acid-base balance, but let’s face it, the kidney’s are complex things and I’m still in the midst of Renal Acid Loads!  That post might take a little while…

Recently I’ve been reading a lot about essential fatty acids (EFAs), with particular reference to fish oils.  A few things have been going around my mind on this, prompted by a comment on another blog, observing that cold-water fish store energy in the form of polyunsaturated fatty acids (you know, PUFAs, the things being stuffed into everything in sight in the food industry) because these oils remain liquid at low temperature (otherwise the sea beds would be piled-up with fish rigid and unable to swim, like butter straight out of the fridge).  We, on the other hand, maintain a positively tropical 37 degrees C (another side-research interest at the moment is the concept of set points – do we actually maintain our systems with this set temperature in mind, or do the regulatory mechanisms involved merely make it seem so?  Body weight is another example of this phenomenon).

So from an evolutionary point of view, where is the critical pressure to retain these PUFAs in significant amounts coming from?

Combine this with a few other things, in no particular order:

  • The longest running observation of fish oil supplementation over 4 years (the DART 2 trial)  demonstrated an increase in all-cause mortality associated with fish oil supplementation
  • Eicosapentaenoic acid (EPA), a fatty acid in fish oil, and usually barely present in mammalian bodies is present in significant quantities in fish oil.  It is converted into docosahexaenoic acid (DHA) once we consume it, but in doing so it ‘hogs’ the enzymatic pathways that converts the omega 6 acid linoleic acid into the essential fatty acid arachidonic acid.  This is a similar mechanism to that of Non-Steroidal Anti-Inflammatory drugs (NSAIDs). However, arachidonic acid isn’t just a precursor for inflammation, it generates many other compounds, both pro- and anti-inflammatory.  Shutting it down, with excess EPA or alpha linolenic acid is akin to using statins to knock-out cholesterol production
  • It is virtually impossible to stimulate a fatty acid deficiency in mature mammals
  • PUFAs are delicate.  They are oxidised easily.  The macrophages that invade and subsequently reside in atherosclerotic plaques grow large and become foam cells by their preferential uptake of oxidised blood lipids.  Reducing the sheer quantity of vulnerable PUFAs in the diet may therefore assist in the reduction of foam cell size
  • Eating oily fish (and fish oil supplementation) mimics only a portion of the hunter-gatherer diets of populations in regions such as the Arctic.  The large quantity of pre-formed arachidonic acid available in the organ meats of mammals in these regions would prevent an imbalance in the EFAs (as would a diet rich in Vitamin B6)

So that’s what I’m researching at the moment!  If that was all way over you head, then fear not, I shall attempt a proper breakdown soon with an in-depth post.  If you have any questions on the subject, feel free to leave them in the comments below and I’ll try to address them.

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