Ground flaxseed reverses protection of a reduced fat diet against Citrobacter rodentium-induced colitis. mouse gut metagenome

Flaxseed is high in omega-3 polyunsaturated fatty acids, fiber and lignans known to lower cholesterol levels. However, its use for prevention or treatment of inflammatory bowel diseases has yielded mixed results, perhaps related to dietary interactions. In this study, we evaluated the impact of ground flaxseed supplementation on the severity of Citrobacter rodentium-induced colitis in the setting of either a high fat (HF; ~36 %kcal) or reduced fat (RF; ~12 %kcal) diet. After weaning, C57BL/6 mice (n=8-15/treatment) were fed ground flaxseed (7g/100g diet) with either HF (HF Flx) or RF (RF Flx) diets for four weeks prior to infection with C. rodentium or sham gavage. Weight changes, mucosal inflammation, pathogen burden, gut microbiota composition, tissue polyunsaturated fatty acids and cecal short-chain fatty acids were compared over a 14-day infection period. A RF diet protected against C. rodentium-induced colitis, whereas a RF Flx diet increased pathogen burden, exacerbated gut inflammation and promoted gut dysbiosis. Compared with a RF diet, both HF and HF Flx diets resulted in more severe pathology in response to C. rodentium infection. Our findings demonstrate that although a RF diet protected against C. rodentium-induced colitis and associated gut dysbiosis in mice, beneficial effects were diminished with ground flaxseed supplementation.