Estimation and predictors of the Omega-3 Index in the UK Biobank

Information on the Omega-3 Index (O3I) in the United Kingdom (UK) is scarce. The UK-Biobank (UKBB) contains data on total plasma n3-PUFA% and DHA% measured by NMR. The aim of our study was to create an equation to estimate the O3I (eO3I) from these data. We first performed an inter-laboratory experiment with 250 random blood samples in which the O3I was measured in erythrocytes by GC, and total n3 % and DHA% were measured in plasma by NMR. The best predictor of eO3I included both DHA% and a derived metric, the total n3 %-DHA%. Together these explained 65 % of the variability (r = 0 center dot 832, P < 0 center dot 0001). We then estimated the O3I in 117 108 UKBB subjects and correlated it with demographic and lifestyle variables in multivariable-adjusted models. The mean eO3I was 5 center dot 58 % (sd 2 center dot 35 %) in this UKBB cohort. Several predictors were significantly correlated with eO3I (all P < 0 center dot 0001). In general order of impact and with directionality (-, inverse and +, direct): oily-fish consumption (+), fish oil supplement use (+), female sex (+), older age (+), alcohol use (+), smoking (-), higher waist circumference and BMI (-), lower socioeconomic status and less education (-). Only 20 center dot 5 % of eO3I variability could be explained by predictors investigated, and oily fish consumption accounted for 7 center dot 0 % of that. With the availability of the eO3I in the UKBB cohort, we will be in a position to link risk for a variety of diseases with this commonly used and well-documented marker of n3-PUFA biostatus.

Automated summary

This study aimed to estimate the Omega-3 Index (O3I) in the UK population and found that fish consumption, particularly oily fish, is an important determinant of the O3I. The study also identified several demographic and lifestyle factors that are correlated with the O3I.