Fish oil supplementation does not impair the gut immune response to Trichinella spiralis infection in rats.

Background: Fish oil has been recommended as a source of omega-3 fatty acids for preterm infants and for therapy of some inflammatory diseases.

Methods: Because fish oil supplementation could downregulate the host's immune response, we studied the gut inflammatory response to an enteric infection in 72 rats assigned to three dietary groups with differing fatty acid profile: 1) fish oil, rich in eicosapentaenoic and docosahexaenoic acid; 2) olive oil, containing 71% monounsaturated fat; and 3) rat chow, containing 57% saturated fat. One half (n = 36) of the rats were infected with Trichinella spiralis larvae; the other half served as controls. The inflammatory response to initial infection (study 1), and type I hypersensitivity response to a subsequent parasite-derived antigenic challenge (study 2) were assessed. Jejunal inflammatory cell infiltrate, mean villus height, disaccharidase levels, changes in short-circuit current in response to glucose absorption, and chloride secretagogues (study 1) were measured 9 days after infection. Short-circuit current changes induced by chloride secretion were measured when the proximal jejunum was challenged with T. spiralis-derived antigen 40 days after infection (study 2).

Results: In study 1, jejunal tissue from infected animals had more eosinophilic infiltrate, lower disaccharidase levels, and less glucose absorptive and chloride secretory capacity than tissue from noninfected animals. In study 2, the jejunum of infected animals showed an antigen-induced chloride secretory response, whereas no response was obtained from jejunal tissue from noninfected animals. Type of diet did not affect the response in either study.

Conclusion: Under the conditions of this experiment, fish oil supplementation did not interfere with the local intestinal inflammatory response after T. spiralis infection.