Fish oil reduces ethanol‐induced damage of the duodenal mucosa in humans

Abstract. Eight healthy volunteers were studied before and after 3 weeks of dietary supplementation with fish oil (10.5 g day^‐1, 18% (1.9 g) eicosapentaenoic acid). Duodenal mucosal lesions were induced by instillation of 40 ml ethanol (40%). Mean endoscopic lesion score was lower after fish oil treatment (1.62±0.32; mean±M) than before (3.25±0.31; P<0.01). Histologic lesion score fell from 22.75±1.98 before treatment to 13.50±1.51 after fish oil (P<0.01). Basal and pentagastrin‐stimulated gastric acid output remained unaffected. Release of prostaglandin E₂, 6‐keto‐prostaglandin F_1α, and thromboxane B₂ from biopsy specimens of the duodenal mucosa in vitro was not significantly altered after fish oil ingestion. In the same in vitro system calcium ionophore A23187‐induced release of total leukotriene C (LTC) increased from 10.6±1.5 ng g^‐1mucosa 20 min before treatment to 30.4±3.2 ng after fish oil. High pressure liquid chromatography analysis showed that this increase was partly due to formation of LTC₅ as after fish oil 28% of total LTC were identified as LTC₅ whereas 72% were LTC₄. We conclude that in humans fish oil reduces ethanol‐induced damage of the duodenal mucosa without inhibiting gastric acid secretion or stimulating prostaglandin formation. It remains to be clarified if the changes in leukotriene formation are relevant for the mucosaprotective fish oil effect.