Polygenic predisposition modifies the associations of fish oil supplementation with circulating omega-3 fatty acids: a cross-sectional gene-diet interaction study in UK Biobank

Background: Several genetic variants have been identified to modify the effects of fish oil supplementation (FOS) on increasing circulating omega-3 fatty acids, but it remains unexplored whether polygenic predisposition to low circulating omega-3 fatty acids modifies these effects. Objective: To test if polygenic scores (PGS) for circulating omega-3 fatty acids modify the associations of FOS with corresponding circulating concentrations. Methods: We developed PGS models for absolute circulating concentrations of total omega-3 fatty acids (Omega-3), docosahexaenoic acid (DHA), and their relative percentages in total fatty acids (Omega-3% and DHA%), using a multi-ethnic genome-wide association study (N=136,016). PGS models were validated in 437,803 UK Biobank participants of European (EUR), Central/South Asian (CSA), African, and East Asian genetic ancestries. Linear models tested PGS-by-FOS interactions on corresponding observed circulating concentrations. Discovery analysis was performed separately in 237,380 EUR participants and each non-EUR group. Replication analyses were performed using oily fish intake and in another 178,935 EUR participants. Results: ). These interaction patterns were consistently observed in CSA ancestry and confirmed in replication and sensitivity analyses. Conclusions: PGS modify the associations of FOS with circulating omega-3 fatty acids in EUR and CSA populations, with larger FOS effects in participants with lower PGS. These findings support the development of genome-informed precision nutrition.