STARCH DIGESTION IN YOUNG-CHILDREN WITH CYSTIC-FIBROSIS MEASURED USING A C-13 BREATH TEST

The study was designed to evaluate a noninvasive breath test using naturally C-13-rich corn (maize) as substrate to provide quantitative information about the digestion of starch by children in health and disease. The variability of background C-13:C-12 of young British children was investigated by collecting breath samples over 6 h from 17 healthy children, 6-35 mo old, and from seven children with cystic fibrosis, 25-48 mo old, in their homes. Background C-13 enrichment was -26.6 and -25.4 partial derivative per mil in the healthy and cystic fibrosis groups, respectively (p < 0.01), and varied little during the day (SD = 0.4 partial derivative per mil). Eight healthy children and five with cystic fibrosis were given a test breakfast of corn starch cooked in milk with sugar. The cystic fibrosis group repeated the test with the addition of an enzyme supplement containing alpha-amylase. Subjects accepted variable amounts of starch (range 0.2-2.8 g/kg body wt). The percentage of ingested C-13 recovered during the 6 h after the meal increased with age in the healthy children (range 15-53%). Three children with cystic fibrosis had negligible C-13 recoveries, and the other two had lower recoveries than expected for their age. The addition of enzymes did not consistently improve C-13 recovery. We conclude that the C-13 breath test based on corn has potential for investigating starch digestion in young children. Initial results suggest that starch digestion is impaired in some children with cystic fibrosis and that enzyme supplements do not improve digestion consistently or completely.