The effect of nutritional rehabilitation on whole body protein metabolism of children with cystic fibrosis.

The effect of an increased energy and protein intake was studied on the whole body protein metabolism of 4- to 9-yr-old children with cystic fibrosis. The study was divided into an initial 1-yr period, followed by a treatment period of the same length. Rates of protein turnover were determined using a [15N]glycine label and the Picou and Taylor-Roberts model. The children had significantly higher intakes during the treatment year and grew faster. Nitrogen retention and utilization were significantly increased during the treatment year (p less than 0.01). There were no changes seen in whole body amino nitrogen flux, or protein synthesis rates. However, protein breakdown rates were significantly reduced during the treatment period, with the result that net anabolism (synthesis-breakdown) was increased (p less than 0.05). The protein synthesis rates of about 6 g/kg/day were similar to those reported for healthy children of the same age. It was concluded that the changes in protein turnover seen were in response to the nutritional intervention and not to the children's basic genetic disease process.