Studies suggest that consumption of omega-3 (n-3)
polyunsaturated fatty acids (PUFA) plays a protective role in
inflammatory bowel disease; however, the use of plant-derived
oils rich in α-
linolenic acid (ALA) has not been widely investigated. The aims of this study were to test the effects of two different sources of (n-3) PUFA, fish and plant-derived
oils, in two animal models of experimental
colitis and to determine whether the (n-3) PUFA-enriched diets could ameliorate the inflammatory status. Rats were fed diets rich in corn, fish or sage oil with or without
vitamin A supplementation for 3weeks then
colitis was induced by adding
dextran sodium sulfate to the
drinking water or by injecting
2,4,6-trinitrobenzene sulfonic acid. We show that colitic rats fed the sage oil diets had a lower inflammatory response, improved histological repair and had less necrotic damage in the mucosa when compared to the corn and
fish oil groups. Colonic damage and
myeloperoxidase activity were significantly lower. Colonic
mRNA levels of pro-inflammatory genes including
interleukin IL-6,
cyclooxygenase 2 and
tumor necrosis factor α were markedly down-regulated in rats fed fish and sage
oils compared to control. These results were supported by experiments in the human colonic epithelial cell line Caco-2, where ALA supplementation was shown to be effective in inhibiting
inflammation induced by IL-1β by down-regulating
mRNA levels of pro-inflammatory genes including
IL-8, COX2 and
inducible nitric oxide synthase. Taken together, these results suggest that plant-derived oil rich in ALA could ameliorate the inflammatory damage in
colitis.