Background: Benefits (decreased septic complications & length of stay) of enteral feeding with immune-enhancing diets (IED) depend on route (enteral vs. parenteral), timing (early vs. delayed) and composition (i.e., omega-3 fatty acids, arginine or RNA nucleotides). A central question is, why does enteral IED delivery provide benefits while parenteral delivery does not. We hypothesized that chronic feeding with certain individual immunonutrients would enhance gastrointestinal blood flow.
Methods: Male Sprague-Dawley rats (200-225g) were fed a standard enteral diet supplemented with immunonutrients for 5 days prior to study. Study groups (n=8) were: 1) standard rat chow; 2) liquid control diet alone (CD); 3) CD + Fish Oil; 4) CD + L-arginine; and 5) CD + RNA nucleotide fragments. Whole organ blood flow distribution was measured by colorimetric microsphere technique in antrum, small intestine (in thirds), colon, liver, spleen, pancreas and kidneys.
Results: Chronic feeding with CD + Fish Oil increased blood flow in the distal third of the small intestine compared to CD alone. CD + L-arginine decreased blood flow in the small intestine (all segments) compared to CD alone. CD + RNA did not alter blood flow distribution.
Conclusions: These findings agree with prior studies of acute gavage 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 GI perfusion might partially explain the benefits of early enteral feeding with immune-enhancing diets not seen with parenteral immunonutrient delivery.