Circulating Omega-3 Fatty Acids and Cardiometabolic Outcomes: A Systematic Review of Publications From UK Biobank.
Level 3 - non-randomized controlled study
Systematic review of observational (cross-sectional and longitudinal cohort) studies.
PubMed 42522977 · doi:10.1002/lipd.70076
What was done
A systematic review was conducted across three databases (EMBASE, MEDLINE, and CINAHL) through September 2025 to examine associations between plasma omega-3 fatty acids (total omega-3, DHA, and non-DHA omega-3) and cardiometabolic health outcomes in UK Biobank publications. Sixteen publications were included: two cross-sectional studies and 14 longitudinal cohort studies with follow-up periods ranging from 11 to 14 years. Sample sizes across the included studies ranged from 20,338 to 273,834 participants. Eleven studies evaluated cardiovascular outcomes and five evaluated metabolic outcomes.
What was found
The abstract reports directional associations without quantitative effect sizes, hazard ratios, or confidence intervals. Higher plasma total omega-3 and DHA were inversely associated with risks of coronary heart disease, cardiovascular mortality, heart failure, haemorrhagic stroke, and severe fatty liver disease. Higher total omega-3 levels were also inversely associated with prediabetes and type-2 diabetes. Higher DHA was additionally inversely associated with coronary heart disease mortality, ischemic stroke, and fatty liver disease.
Why it matters
This review compiles large-scale biomarker evidence showing consistent observational associations between circulating omega-3 fatty acid levels and reduced cardiometabolic risk across a massive prospective cohort.
Limits
All included studies derive from the same underlying cohort (UK Biobank), creating substantial sample overlap and limiting generalizability beyond this predominantly white, middle-aged British population. The abstract provides no quantitative meta-analysis, pooled risk estimates, or precision metrics. As with all observational designs, these associations are vulnerable to residual confounding and cannot establish causal protection.