Fish oil increases blood flow in the ileum during chronic feeding in rats

Benefits of enteral feeding with immune-enhancing diets (IEDs) depend on route, timing, and composition. We hypothesized that chronic enteral feeding with certain individual immunonutrients would enhance gastrointestinal blood flow. Male rats were fed a standard enteral diet supplemented with immunonutrients for 5 days before study. Groups were (1) standard rat chow, (2) liquid control diet (CD) alone (CD), (3) CD + fish oil, (4) CD + L-arginine, and (5) CD + RNA fragments. Whole organ blood flow distribution was measured by colorimetric microsphere technique in antrum, small intestine (in thirds), colon, liver, spleen, pancreas, and kidneys. Chronic feeding for 5 days with CD + fish oil increased blood flow in the distal third of the small intestine compared with CD alone, whereas feeding with CD + L-arginine decreased blood flow in the small intestine (all segments) compared with CD alone. Acute gavage of CD + L-arginine or CD + fish oil increased blood flow in the proximal and middle third of the small intestine compared with CD alone. Control diet + RNA increased blood flow in the proximal small intestine compared with CD alone. These findings support prior acute feeding studies with CD, CD + individual immunonutrients, or IED. Our current data suggest that blood flow benefits associated with fish oil persist during chronic feeding in rats. Enhanced gastrointestinal perfusion might partially explain the benefits of early enteral feeding with IEDs not seen with regular enteral diets and parenteral immunonutrient delivery.