Determinants of the Omega-3 Index in the UK Biobank

Abstract

Information on the Omega-3 Index (O3I) in the United Kingdom (UK) are scarce. The UK-Biobank (UKBB) contains data on total plasma omega-3 polyunsaturated fatty acids (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 interlaboratory experiment with 250 random blood samples in which the O3I was measured in erythrocytes by gas chromatography, 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=0.832, p<0.0001). We then estimated the O3I in 117,108 UKBB subjects and correlated it with demographic and lifestyle variables in multivariable adjusted models. The mean (SD) eO3I was 5.58% (2.35%) this UKBB cohort. Several predictors were significantly correlated with eO3I (all p<0.0001). In general order of impact and with directionality (- = inverse, + = 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 20.5% of eO3I variability could be explained by predictors investigated, and oily-fish consumption accounted for 7.0% 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.

Association between Blood N-3 Fatty Acid Levels and Risk for COVID-19 in the UK biobank

“…Unfortunately, data on vaccination status were not available for this analysis, but in order for differential vaccination status to have biased our results, one would have to posit that people with higher n-3 levels were more likely to have been vaccinated than those with lower levels during the approximately 3-4 month period of this study for which vaccines were available (Dec 2020-March 2021). Although this is plausible [i.e., higher n-3 levels are associated with higher SES and healthful behaviors and exercise and a greater consumption of oily fish and fish oil supplements(19)], we are unable to confirm or deny this hypothesis.…”

“…A study in 26 children with multi-system inflammatory syndrome linked to COVID-19 infection found lower levels of EPA and DHA compared with historical controls (28). Other reports from within the UKBB have described significant inverse relationships between reported fish oil supplement use (which is associated with a higher O3I (19) and risk for death from all causes, risk for incident cardiovascular events(29) as well as primary liver cancer (30), inflammatory bowel disease (31) and dementia (32).…”

“…Exposure: The primary exposure was plasma DHA (expressed as a percent of total plasma fatty acids) obtained from blood samples collected at time of enrollment using by NMR (Nightingale Health Plc, Helsinki, Finland (18)). In order to estimate the O3I associated with these DHA levels, we used an equation described by Schuchardt et al (19), which found a correlation between the observed and estimated O3I of 0.83.…”