Effect of glucose to fat ratio on energy substrate disposalin children with cystic fibrosis fed enterally

High fat containing diets lower VCO2 in patients with impaired pulmonary function fed at a high level of energy intake. We tested the effect of a high fat enteral nutrition on VCO2 and substrate oxidation in cystic fibrosis patients fed enterally 130% RDA. VCO2 and substrate oxidation were studied in a group of eight 6–19 year old patients while receiving for 1 month and in a random order isocaloric (1000 kcal/m2), isonitrogenous enteral diet with a normal fat and a high fat content (40% and 67% of non-protein energy intake). Substrate oxidation and net balance were estimated using indirect calorimetry at the end of each study period. Overnight high fat enteral infusion resulted in no significant change in VCO2 and VO2 but lowered RQ (0.84 ± 0.01 vs 0.88 ± 0.01, P = 0.02) and non-protein RQ (0.83 ± 0.01 vs 0.88 ± 0.01). In spite of a higher glucose oxidation rate (8.1 ± 0.5 vs 6.3 ± 0.5 g. h−1, P = 0.04), glucose net balance was significantly higher during normal fat formula administration (+2.5 ± 0.8 v-0.3 ± 0.7 g/h, P< 0.05). The present study failed to show any benefit of a high fat diet on VCO2 in non oxygenodependant cystic fibrosis children and adolescents fed slightly above RAID. Normal fat enteral formula led to higher glycogen repletion.