Assessing the dietary intake of omega 3 fatty acids and examining the effect of a 6 month supplementation of EPA on blood lipids and inflammatory cytokines in healthy Irish adults

The health benefits of long chain (LC) n-3 polyunsaturated fatty acids (PUFA) are now widely recognised (Tur et al 2012) including triglyceride lowering effects (Lopez-Huertas, 2012) and anti-inflammatory effects (Rangel-Huerta et al 2012). However, intakes of oily fish among Irish adults in the recent national survey show that consumption of fish is low (Irish Universities Nutrition Alliance, 2011) and dietary intakes of LC n-3 PUFA are below international recommendations (Leite et al 2010). This study investigated the dietary intakes of LC n-3 PUFA, specifically, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in a sample of healthy Irish adults. Subsequently, the effects of a 1g EPA supplement for 24 weeks on blood lipids and inflammatory cytokine levels were examined. A pilot study was conducted to determine the preferred dietary assessment method; a food frequency questionnaire (FFQ) and a 4-day food record were compared in a separate sample of older adults (n=37). The results had poor correlation and the 4-day food record was chosen as it was thought that the FFQ would over-estimate fish consumption. The cross sectional study analysed the dietary intake of apparently healthy adults using a 4-day food record. The results were compiled in Weighed Intake Software Package (WISP© Version 3.0) (Tinuviel Software, Warrington, UK) and analysed using an updated fatty acid database following the method of Leite et al (2010). The double-blind randomised controlled trial provided subjects with a 1g EPA supplement or placebo and measured the change in blood lipid profile and inflammatory cytokines in healthy adults after 24 weeks. Median EPA and DHA intakes were compared to reference data. Changes in blood lipids and inflammatory cytokines were analysed for statistical significance using the Wilcoxon Sign test and the Friedman test. Less than 10% of adults in this study met the recommended intakes of EPA and DHA. As expected, intakes among fish consumers were significantly higher than non-fish consumers. Compared to placebo blood lipids were not significantly different following 24 weeks of EPA supplementation. In the control group the median concentration of circulating IL-1β decreased by 24% (1.16pg/ml vs. 0.88pg/ml; p=0.001) and IL-6 by 7.7% (3.11pg/ml vs. 2.87pg/ml; p = 0.007); the other cytokines remained unchanged. The majority of adults in this study did not meet recommendations for dietary LC n-3 PUFA intakes. The effect of a 1g EPA supplement on lipid profiles and inflammatory cytokines was not conclusive; this could be explained in part by the low lipid and cytokine levels at baseline in this healthy population.