Fish oil (FO) has been shown to have anti-inflammatory properties in animal models of
inflammatory bowel disease, but how fish
peptides (FP) influence intestinal
inflammation has been less studied. Male Wistar rats, divided into five groups, were included in a 4-week dietary intervention study. Of the groups, four were exposed in the fourth week to 5 %
dextran sulfate sodium (DSS) to induce
colitis, while one group was unexposed. The diets were: (1) control, (2) control + DSS, (3) FO (5 %) + DSS, (4) FP (3·5 %) + DSS, (5) FO + FP + DSS. Following DSS intake, weight and disease activity index (DAI) were assessed, and histological combined score (HCS), selected colonic PG,
cytokines, oxidative damage markers and
mRNA levels were measured. FP reduced HCS, tended to lower DAI (P = 0·07) and reduced keratinocyte
chemoattractant/growth-regulated oncogene levels, as compared with the FO diet. FP also reduced
mRNA levels of
Il-6 and Cxcl1, although not significantly. FO intake increased the DAI as compared with DSS alone.
PGE3 levels increased after the FO diet, and even more following FO + FP intake. The FP diet seems to have a protective effect in DSS-induced
colitis as compared with FO. A number of beneficial, but non-significant, changes also occurred after FP v. DSS. A combined FO + FP diet may influence PG synthesis, as
PGE3 levels were higher after the combined diet than after FO alone.