Is the Omega-3 Index Higher in Coastal Than Inland US Cities?

Abstract

ObjectivesHigher omega-3 fatty acid blood levels, as assessed by the Omega-3 Index (O3I, erythrocyte EPA + DHA expressed as a % of total fatty acids), have been linked with lower risk for cardiovascular disease and total mortality. Seafood is an excellent source of EPA and DHA. The purpose of this study was to determine if individuals living in a coastal US city (Newport, RI) with direct access to fresh seafood have higher O3I levels than people living in inland cities. MethodsDried blood spot samples were collected from a convenience sample of people attending a sponsored health fair on the boardwalk in Newport, RI between July and August 2019. Attendees interested in obtaining their O3I signed a consent form before testing and then provided a drop of blood for testing. As a comparator inland group, we used published data (Harris et al. PLEFA 2019;148:30–34) from 7 US cities in the “stroke belt” (note, only one of the 7 cities was coastal, Jacksonville, FL). Dried blood samples were analyzed for the O3I by gas chromatography in both settings. ResultsThe Newport sample included 234 individuals, 50/50 male/female, with a mean (SD) age of 46 (16) years. The 7 cities comparator cohort contained 2177 subjects, with a mean age of 48 (16) years and of those reporting gender, 78% were female. The mean (SD) O3I in Newport was 5.15% (1.37%), whereas in the 7 cities study it was 4.42% (1.12%; P < 0.0001). An O3I of ≤4% (considered low) was found in 21% of the Newport subjects compared to 42% in comparator cohort (P < 0.0001). Relatedly, an O3I of >8% (considered optimal) was found in 3% of the Newport sample compared to 1.2% in the 7 cities study (P = 0.19). ConclusionsThese data support our hypothesis that the O3I is higher in populations living in a coastal city than those living inland. Still, only 3% of individuals with immediate access to fresh seafood had O3I levels in the optimal zone. Given the documented health benefits of having an optimal O3I, increased intakes of EPA and DHA from fish and other dietary sources or supplementation should be recommended. Funding SourcesRB Health (US) LLC.