Association between Plasma Nonesterified Fatty Acids Species and Adipose Tissue Fatty Acid Composition

Christian Hellmuth,Berthold Koletzko,Isabel Schmitt,Wolfgang Peissner,Hans Demmelmair,Matthias Blüher,Lorraine Brennan

doi:10.1371/journal.pone.0074927

Abstract

Fatty acid composition of adipose tissue (AT) is an established long-term biomarker for fatty acid (FA) intake and status, but AT samples are not easily available. Nonesterified FA composition in plasma (pNEFA) may be a good indicator of AT FA composition, because pNEFA are mainly generated by AT lipolysis. We investigated the correlation of 42 pNEFA and subcutaneous as well as visceral AT FA in 27 non-diabetic women with a median BMI of 36 kg/m2 (Q0.25: 25 kg/m2; Q0.75: 49 kg/m2). Close correlations of pNEFA and AT FA were found for odd-chain FA (15∶0 r = 0.838 and 0.862 for subcutaneous and visceral AT, respectively) and omega-3 FA (22∶6 r = 0.719/0.535), while no significant or low correlations were found for other FA including 18∶1 (r = 0.384/0.325) and 20∶4 (r = 0.386/0.266). Close correlations of pNEFA and AT FA were found for essential fatty acids, like 18∶2 (r = 0.541/0.610) and 20∶5 (r = 0.561/0.543). The lower correlation for some pNEFA species with AT FA indicates that the variation of most pNEFA is significantly affected by other FA sources and flux of FA to tissue, in addition to release from AT. A relevant influence of BMI on the level of correlation was shown for saturated FA. NEFA analysis in fasted plasma can serve as a virtual AT biopsy for some FA, and as a biomarker for intake of dairy products and sea fish.

Highlights

Fatty acid (FA) composition of adipose tissue (AT) is a wellaccepted biomarker for the assessment of long-term dietary FA intake, considered to be superior to dietary records and food frequency questionnaires [1]
Significant differences in FA composition between both sites of AT were mainly found for very long-chain fatty acids (VLCFA) which were higher in visceral adipose tissue (vAT), and some polyunsaturated FA (PUFA) with significantly higher contribution to subcutaneous adipose tissue (sAT) (Table1)
Plotting the ratio of sAT to vAT percentages versus carbon chain-length and number of double bonds indicated a clear trend for preferential incorporation of highly unsaturated FA into sAT, while longer carbon chain FA tended to be higher in vAT (Figure1)

Summary

Introduction

Fatty acid (FA) composition of adipose tissue (AT) is a wellaccepted biomarker for the assessment of long-term dietary FA intake, considered to be superior to dietary records and food frequency questionnaires [1]. Percentage contributions of FA in AT, representing intake of dairy products, fish or fish oil are highly correlated to dietary intake [2,3]. While essential polyunsaturated FA (PUFA) show a close relationship between dietary intake and AT content, saturated FA (SFA) and monounsaturated FA (MUFA) are less closely correlated [4], presumably because these FA are derived from both diet and endogenous synthesis [5]. SFA and MUFA in AT are of importance as biomarkers for various disease risks [3]. AT lipolysis releases nonesterified fatty acids into plasma (pNEFA). PNEFA could provide a valuable surrogate marker for AT FA composition

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