How KIM calculates cellular membrane HUFA ratios

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Hi All,

Thanks to Deborah Pageau on the VegScience list, this paper is the basis for the

equations KIM uses to predict the

ratios of n6l to n3l in cellular membranes and thus the effect of dietary PUFAs

on eicosanoid balance.

This is shown in text form at:

http://ods.od.nih.gov/eicosanoids/#3.-%20Ratios%20in%20Diets%20and%20Tissues

and graphically at:

http://ods.od.nih.gov/eicosanoids/eicosa2.gif

If anyone can get a full text copy, let me know & I'll post it so we can all

read it.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=PubMed & list_uids=1\

463766 & dopt=Abstract

Biochim Biophys Acta 1992 Dec 10;1180(2):147-62

Maintenance of lower proportions of (n - 6) eicosanoid precursors in

phospholipids of human plasma in response to added

dietary (n - 3) fatty acids.

Lands WE, Libelt B, A, Kramer NC, Prewitt TE, Bowen P, Schmeisser D,

son MH, Burns JH.

Department of Biological Chemistry, University of Illinois, Chicago.

Competition between the (n - 3) and (n - 6) types of highly unsaturated fatty

acids can diminish the abundance of (n -

6) eicosanoid precursors in a tissue, which in turn can diminish the intensity

of tissue responses that are mediated by

(n - 6) eicosanoids.

The mixture of 20- and 22-carbon highly unsaturated fatty acids maintained in

the phospholipids of human plasma is

related to the dietary intake of 18:2 (n - 6) and 18:3 (n - 3) by empirical

hyperbolic equations in a manner very

similar to the relationship reported for laboratory rats (Lands, W.E.M., ,

A. and Libelt, B. (1990) Lipids 25,

505-516).

Analytical results from volunteers ingesting self-selected diets showed an

inter-individual variance for the proportion

of (n - 6) eicosanoid precursors in the fatty acids of plasma phospholipids of

about 5%, but the variance among multiple

samples taken from the same individual throughout the day was less (about 3%),

closer to the experimental variance of

the analytical procedure (about 1%).

The reproducibility of the results makes it likely that analysis of fatty-acid

composition of plasma lipids from

individuals will prove useful in estimating the diet-related tendency for severe

thrombotic, arthritic or other

disorders that are mediated by (n - 6) eicosanoids.

Additional constants and terms were included in the equations to account for the

effects of 20- [EPA] and 22- [DHA]

carbon highly unsaturated (n - 3) fatty acids in the diet.

A lower constant for the 20- [EPA] and 22- [DHA] carbon (n - 3) fatty acids

compared to that for the 18-carbon (n - 3)

[Omega 3] fatty acid in decreasing the ability of dietary 18:2 (n - 6) [Omega 6]

to maintain 20:4 (n - 6) [AA] in tissue

lipids confirmed the greater competitive effectiveness of the more highly

unsaturated n - 3 fatty acids [EPA, DHA] in

the elongation/desaturation process.

Also, a lower constant for direct incorporation of 20-carbon fatty acids of the

n - 6 [DGLA, AA] vs. the n - 3 [EPA]

type indicated a greater competitive effectiveness of 20:4 (n - 6) [AA] relative

to 20:5 (n - 3) [EPA] in

reesterification after release from tissue lipids.

The equations may be used in reverse to estimate the dietary intakes of the (n -

3) and (n - 6) fatty acids by using the

composition of the fatty acids that had been maintained in plasma lipids.

PMID: 1463766 [PubMed - indexed for MEDLINE]

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What all that boils down to is that direct dietary intake of EPA has a big

effect on altering the eicosanoid balance in

favour of more good messengers.

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Good Health & Long Life,

Greg ,

http://www.ozemail.com.au/~gowatson

gowatson@...