Omega-3 Fatty Acid Status Biomarkers: Analytical Validity, Clinical Utility, and Public Health Applications – A Narrative Review

Abstract

Omega-3 polyunsaturated fatty acids (PUFAs), particularly eicosapentaenoic acid and docosahexaenoic acid, are essential to cardiovascular, neurological, metabolic, and immune function. Despite substantial evidence supporting their biological importance, intake remains inadequate in many populations worldwide. Because dietary assessment methods are limited by recall bias, reporting error, and variation in food composition, objective biomarkers are increasingly used to assess physiological omega-3 status. This narrative review examines the scientific basis, analytical validity, clinical relevance, and public health applications of the principal omega-3 biomarkers, with emphasis on the Omega-3 Index, the omega-6:omega-3 ratio, and dried blood spot testing. The Omega-3 Index, based on red blood cell EPA and DHA content, emerges as the most robust marker of long-term omega-3 status and the one most consistently associated with clinically relevant outcomes, particularly in cardiovascular health. The omega-6:omega-3 ratio offers complementary insight into dietary balance and inflammatory context, although its interpretive limitations reduce its value as a stand-alone marker. Dried blood spot testing has broadened access to fatty acid assessment by enabling minimally invasive, scalable sampling suitable for both clinical and population-level use. Together, these biomarkers support a shift toward more objective, individualised, and prevention-orientated approaches to nutrition assessment. Their wider integration into healthcare and public health practice may improve risk stratification, guide intervention, and strengthen population monitoring of omega-3 sufficiency.