monounsaturates and omega 3,6

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Adam Becker Sr - 11 Oct 2004 03:58 GMT

Is there such a thing as a monounsaturated omega-3 fatty acid?

I'm trying to get clear on omega-3/6 fatty acids. The definitions
that I've read seem to say that an omega-3 fatty acid is one that is
unsaturated at the 3rd carbon/carbon bond from the methyl end. So
would an 18-carbon fatty acid, with just one double bond at the 3rd
position, be an omega-3 fatty acid?

Is such a fat commonly found in nature?

All the discussion I read of omega-3,6 start with linoleic and
linolenic acids, which are di-unsaturated. The discussions I read of
monounsaturated oils, like olive oil, talk about oleic acid as a major
constituent but don't classify it as omega-anything (or tell me where
it's saturation is.)

Also, are omega-3,6 acids of less than 18 carbons found in dietary
sources? Can our bodies utilize them - lengthen them to 18, 20, 22
carbons?
Thanks for any guidance

Adam Becker

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Matti Narkia - 11 Oct 2004 05:31 GMT

10 Oct 2004 19:58:33 -0700 in article
<97066089.0410101858.36bef10c@posting.google.com> adam_becker_sr@yahoo.com

>Is there such a thing as a monounsaturated omega-3 fatty acid?

Not to my knowledge.

>I'm trying to get clear on omega-3/6 fatty acids. The definitions
>that I've read seem to say that an omega-3 fatty acid is one that is
>unsaturated at the 3rd carbon/carbon bond from the methyl end. So
>would an 18-carbon fatty acid, with just one double bond at the 3rd
>position, be an omega-3 fatty acid?

IMHO yes, if such a fatty acid existed, but to my knowledge it doesn't.

>Is such a fat commonly found in nature?

Not to my knowledge.

>All the discussion I read of omega-3,6 start with linoleic and
>linolenic acids, which are di-unsaturated.

Only linoleic acid is di-unsaturated. Linolenic acid acid has three double
bonds, so it would be tri-unsaturated.

>The discussions I read of
>monounsaturated oils, like olive oil, talk about oleic acid as a major
>constituent but don't classify it as omega-anything (or tell me where
>it's saturation is.)

Oleic acid is an omega-9 fatty acid.

>Also, are omega-3,6 acids of less than 18 carbons found in dietary
>sources?

Not to my knowledge.

For more information about fatty acids see

Introduction to Fatty Acids
<URL:http://www.pufanewsletter.com/intro_1.html>

Fats You Need -- Essential Fatty Acids
<URL:http://www.benbest.com/health/essfat.html>

NetBiochem -- Fatty Acids
<URL:http://medlib.med.utah.edu/NetBiochem/FattyAcids/index.html>

All about Lipids
<URL:http://www.lipidlibrary.co.uk/lipids.html>

EFA Education
<URL:http://efaeducation.nih.gov/>

EFA:Chain Lengths & Metabolism
<URL:http://efaeducation.nih.gov/sig/overview2.html>

Lipids
<URL:http://www.mansfield.ohio-state.edu/~sabedon/biol1030.htm>

The Omega-3 Polyunsaturates
<URL:http://www.fish-foundation.org.uk/omega-3.htm>

Kris-Etherton PM, Taylor DS, Yu-Poth S, Huth P, Moriarty K, Fishell V,
Hargrove RL, Zhao G, Etherton TD.
Polyunsaturated fatty acids in the food chain in the United States.
Am J Clin Nutr. 2000 Jan;71(1 Suppl):179S-88S. Review.
<URL:http://www.ajcn.org/cgi/content/full/71/1/179>

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Matti Narkia

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Adam Becker Sr - 11 Oct 2004 16:36 GMT

[lotsa good answers]

Thanks Matti for a very helpful and informative answer, along with a
whole bunch of good links. I've been reading through the info at the
PUFA Newsletter site. They are laying the information out in a MUCH
more legible way than the other sites that I'd found by googling.
(The NIH site in particular was full of good info presented
incomprehensibly.)

I'm still trying to get my mind around this. Let me summarize some of
the points I think I've learned - have I got this right?

Monounsaturated fatty acids - principally oleic - incorporated into
cell-wall lipids, increasing their flexibilty (in comparison to trans
or saturated FFA.) Not easily oxidized, therefore low contribution to
oxidative stress. Neutral w.r.t. the omega-3,6 balance. Doesn't
participate in the eicosinid -> COX -> inflamation pathways. Lead to
small increase in HDL, small decrease in LDL.

Polyunsaturated fats - mostly omega-3,6, although also -7 and -9. C18
from vegetable sources; c20, c22 from animal sources; fish oil very
rich in C20, C22 omega-3. Metabolized to AA (omega-6) and DHA
(omega-3.) These fats also increase cell wall flexibility. More
easily oxidized, contribute to oxidative stress. Lead to small
increase in HDL, small decrease in LDL but can increase oxidized VLDL.
Participate in the eicosinid -> COX -> inflamation pathways. Extent,
character of inflamation sensitive to omega-6:omega-3 ratio in tissue.
Ideally the ratio is 1:1, really start seeing problems when it gets
higher than 5:1.

Adam Becker

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