Dietary Fish Oil Supplementation Increases Survival in Mice Following Klebsiella pneumoniae Infection

INTRODUCTION: Epidemiological studies have shown that high intake of omega-3 fatty acids correlates with low incidence of various diseases such as cardiovascular diseases, asthma, diabetes mellitus and various auto-immune disorders. It may therefore be suggested that omega-3 fatty acids have substantial impact on the immune system. Studies of the effect of omega-3 fatty acids on survival in bacterial infections have however been contradicting. A Dutch study from 1991 showed increased survival in mice fed fish-oil following infection with Klebsiella pneumoniae. Because of the contradicting results the authors conducted a study with the hypothesis that fish-oil intake increases survival after severe Klebsiella pneumoniae infection. METHODS: Thirty mice were fed fish-oil enriched diet (10%), olive-oil enriched diet (10%) or standard chow diet. After six weeks the mice were injected intramuscularly with l.óxlO2 cfu of Klebsiella pneumoniae. The survival was measured at regular time intervals for 120 hours. RESULTS: After 56 hours, 93% of the mice fed fish-oil were alive and 68% and 40% of the mice fed olive-oil and standard chow respectively. The overall survival after 120 hours was 40% in the fish-oil group, 25% in the olive-oil group and 20% in the standard group. The survival after 120 hours of the mice fed the fish-oil enriched diet was significantly better when compared to the two other groups (p=0.0034). DISCUSSION: We conclude that fish-oil enriched diet increases survival of NMRI mice following infection with Klebsiella pneumoniae when compared to olive-oil supplementation or standard chaw. We therefore conclude that the difference in survival is probably based on the effect of omega-3 fatty acid on the immune system. The immunological pathway is still unknown and our results encourage further studies.