Research: SCHUSTER and COLLEAGUES,

Listed in Issue 240

Abstract

SCHUSTER and COLLEAGUES, (1)1 United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Western Human Nutrition Research Center, Immunity and Disease Prevention Unit, Davis, California studied airway inflammation  and hyper-responsiveness assessing the effects of consuming EPA, DHA, EPA plus DHA, or a control diet with no added omega-3 polyunsaturated fatty acids.

Background

Although the effects of fish oil supplements on airway inflammation in asthma have been studied with varying results, the independent effects of the fish oil components, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), administered separately, are untested.

Methodology

Here, the authors investigated airway inflammation and hyper-responsiveness using a mouse ovalbumin exposure model of asthma assessing the effects of consuming EPA (1.5% wt/wt), DHA (1.5% wt/wt), EPA plus DHA (0.75% each), or a control diet with no added omega-3 polyunsaturated fatty acids.

Results

Consuming these diets for 6 weeks resulted in erythrocyte membrane EPA contents (molar %) of 9.0 (± 0.6), 3.2 (± 0.2), 6.8 (± 0.5), and 0.01 (± 0.0)%; DHA contents were 6.8 (± 0.1), 15.6 (± 0.5), 12.3 (± 0.3), and 3.8 (± 0.2)%, respectively. The DHA group had the highest bronchoalveolar lavage (BAL) fluid eosinophil and IL-6 levels (P < 0.05). Similar trends were seen for macrophages, IL-4, and IL-13, whereas TNF-α was lower in omega-3 polyunsaturated fatty acid groups than the control (P < 0.05). The DHA group also had the highest airway resistance, which differed significantly from the EPA plus DHA group (P < 0.05), which had the lowest. Oxylipins were measured in plasma and BAL fluid, with DHA and EPA suppressing arachidonic acid-derived oxylipin production. DHA-derived oxylipins from the cytochrome P450 and 15-lipoxygenase pathways correlated significantly with BAL eosinophil levels.

Conclusion

The pro-inflammatory effects of DHA suggest that the adverse effects of individual fatty acid formulations should be thoroughly considered before any use as therapeutic agents in asthma.

References

Schuster GU(1), Bratt JM, Jiang X, Pedersen TL, Grapov D, Adkins Y, Kelley DS, Newman JW, Kenyon NJ, Stephensen CB. Dietary long-chain omega-3 fatty acids do not diminish eosinophilic pulmonary inflammation in mice. Am J Respir Cell Mol Biol. 50(3):626-36. doi: 10.1165/rcmb.2013-0136OC. Mar 2014.

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