Health Questions and Answers

Question: What are the effects of enteral feedings on the immune system?


Enteral feeding is the body’s preferred route of nutrition. Compared to TPN, enterally fed patients have a lower number of septic complications, including bacteremia, abdominal abscess, and pneumonia. It is speculated that the beneficial effects are from prevention of mucosal atrophy and decreased bacterial translocation. But there is little proof in humans. It has been shown that overgowth of pathogenic bacteria occurs when the gut is not used for feeding. These bacteria then have an increased tendency to be cultured from the respiratory tract of ICU patients. Experimental work has shown that upper respiratory immunity is compromised if the gut is not used for nutrition.

The beneficial effects of enteral feedings occur even with small volumes of “trophic” feeds. In head-injured patients, the effect has been noted to occur only if the feedings were started early in the course. The concept that has evolved is one of a “common mucosal immune system.” Once initial activation of precursor IgA- producing cells occurs within the Peyer’s patches, the antigen-sensitized cells undergo mitotic changes and the resulting B lymphoblasts migrate to regional lymph nodes and eventually to the systemic circulation via the thoracic duct. This in turn enhances the systemic response to infection.

Reference:  Kubena KS, Murray DN: Nutrition and Immune system: A review of nutrient-nutrient interactions. J Am Diet Assoc 96 (11): 1156-1164,1996

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