Keeping infectious complications at bay with immunonutrition

Certain nutrients have been shown to influence immunological and inflammatory responses in humans, and a new term, immuno-nutrition, has been coined for the study of foodstuffs complimented with substances that might enhance immunity. This concept is being used by several food companies to promote their products, both for humans and household pets. Whether immunonutrition translates into quantifiable changes in immunity during illness is uncertain still. A recent report by D. Heyland and colleagues at the Kingston General Hospital in Canada analyzed systematically a total of 2419 patients in 22 randomized trials, which compared the use of immunonutrition with standard enteral nutrition in surgical and critically ill patients. The studies involved enteral nutrition supplemented with some combination of arginine, glutamine, nucleotides and omega-3 fatty acids compared with standard nutrition. The outcomes measured included infectious complications and mortality rates. The authors found that the use of commercial formulations with high arginine content was associated with a significant reduction in infectious complications, and a trend towards a lower mortality rate compared with other ‘immune-enhancing’ diets, particularly in surgical patients, rather than in the critically ill. They conclude that the studies suggest immunonutrition might decrease infectious complications but is not associated with an overall advantage in terms of mortality. J. Am. Med. Assoc. (2001) 286, 944–953 LON