A rapid method for determining arachidonic:eicosapentaenoic acid ratios in whole blood lipids: correlation with erythrocyte membrane ratios and validation in a large Italian population of various ages and pathologies

Abstract

BackgroundOmega-3 and -6 polyunsaturated fatty acids (LCPUFA), are important for good health conditions. They are present in membrane phospholipids.The ratio of total n-6:n-3 LCPUFA and arachidonic acid:eicosapentaenoic acid (AA and EPA), should not exceed 5:1. Increased intake of n-6 and decreased consumption of n-3 has resulted in much higher, ca 10/15:1 ratio in RBC fatty acids with the possible appearance of a pathological "scenario". The determination of RBC phospholipid LCPUFA contents and ratios is the method of choice for assessing fatty acid status but it is labour intensive and time consuming.Aims of the study[i] To describe and validate a rapid method, suitable for large scale population studies, for total blood fatty acid assay; [ii] to verify a possible correlation between total n-6:n-3 ratio and AA:EPA ratios in RBC phospholipids and in whole-blood total lipids, [iii] to assess usefulness of these ratio as biomarkers of LCPUFA status.Methods[1] Healthy volunteers and patients with various pathologies were recruited.[2] Fatty acid analyses by GC of methyl esters from directly derivatized whole blood total lipids and from RBC phospholipids were performed on fasting blood samples from 1432 subjects categorised according to their age, sex and any existing pathologies.AA:EPA ratio and the total n-6:n-3 ratio were determined.ResultsAA:EPA ratio is a more sensitive and reliable index for determining changes in total blood fatty acid and it is correlated with the ratio derived from extracted RBC phospholipids.ConclusionsThe described AA:EPA ratio is a simple, rapid and reliable method for determining n-3 fatty acid status.

Secular trend of serum docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid concentrations among Japanese—A 4- and 13-year descriptive epidemiologic study

“…Before the study, we hypothesized that serum DHA, EPA, and ARA would change in a steady pattern with aging because several studies, including our cohort study [4], have shown age-related changes in blood FA as increases in DHA and EPA and decreases in ARA occur [5][6][7][8]. In fact, sex-adjusted serum ARA concentrations according to age groups at the fifth and seventh study wave were lower among the older age groups (Supplementary Table 2).…”

“…These PUFA and eicosapentaenoic (EPA) have been shown to participate in numerous cellular functions affecting membrane fluidity, membrane enzyme activities, and eicosanoid synthesis [3]. Several studies, including our previous cohort study [4], have shown age-related changes in blood fatty acids (FA), as increases in DHA and EPA and decreases in ARA occur over time [5][6][7][8]. We hypothesized that serum DHA, EPA, and ARA changed in a steady pattern with aging.…”

“…However, most previous studies were cross-sectional studies [4][5][6][7][8]; it is thus unknown whether there are age effects on serum FA in the same population.…”

Chemical–Physical Changes in Cell Membrane Microdomains of Breast Cancer Cells After Omega-3 PUFA Incorporation

“…The PUFA concentration of human blood may vary according to age, sex, genetics, diseases and dietary habits [34]. Recent reports from the EPIC-Norfolk cohort study showed that the average concentrations of EPA, DHA in plasma are 56.1 and 236.2 µmol/L respectively with a high individual variability [35].…”

A method for long term stabilisation of long chain polyunsaturated fatty acids in dried blood spots and its clinical application

“…There is particular interest in the bioactive n-3 LCPUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the sum of which, termed the omega-3 index, has been proposed as a measure of risk for death from coronary heart disease [4,5]. However, conventional approaches to assaying fatty acids in blood involve venous blood collection and an expensive, time consuming multi-step process that limit their usefulness as a screening tool.…”