Effect of diet on the metabolic response to infection: protein-sparing modified fast plus 100 grams glucose and yellow fever immunization.

The metabolic response to yellow fever immunization was investigated in four obese subjects who were consuming a protein-sparing modified fast plus 100 g glucose (PSMF + 100 g) for 3 wk. Fasting, 1/2, 1, and 2 h postprandial values for insulin, glucagon, glucose, lactate, beta hydroxybutyrate, acetoacetate, and free fatty acids were assessed before and the 1st, 3rd, and 5th day postimmunization. The hormone and substrate response to dietary protein plus glucose was a substantial rise in insulin (p less than 0.005), glucose (p less than 0.005), and fall in free fatty acid and ketone levels (p less than 0.005). These results are distinctly different from the response to dietary protein ingestion only (PSMF) determined in a previous study which was a slight rise in insulin and glucose and slight fall in ketone bodies, but a substantial rise in glucagon. The only significant (p less than 0.05) change following immunization in the PSMF + 100 g was a rise in serum glucagon on day 1. During the PSMF significant elevations in insulin and lactate and falls in serum ketones were noted postimmunization. The metabolic response to mild infection is dependent on the diet consumed. These differences may have a clinical impact when the infection is severe, but this possibly requires study in an experimental infection of greater severity.