Breath hydrogen response to milk containing lactose in colicky and noncolicky infants

In 122 healthy newborn infants, we studied the relationship between breath hydrogen (H 2 ) production after feedings containing lactose (human milk or commercial formula) in colicky and noncolicky infants at 6 weeks and 3 months. Eighty-three infants (68%) developed colic (mild, moderate, or severe) by 2.6±1.8 weeks of age (mean±SD). Zero time (baseline) breath H 2 values were significantly higher in colicky compared with noncolicky infants at both 6 weeks (40.6±41.4 vs 14.8±32.9 ppm) and 3 months (27.7±38.1 vs 8.5±18.2 ppm). There were significantly more positive breath H 2 tests in colicky compared with noncolicky infants at 6 weeks (78% vs 36%) and 3 months (89% vs 45%). Failure to produce H 2 throughout the breath H 2 test was significantly more frequent in noncolicky compared with colicky infants at 6 weeks (50% vs 18%) and 3 months (43% vs 4%). These findings remained significant even when infants with mild colic (at 6 weeks and 3 months) were included in the noncolicky group. We conclude that colicky infants produce more breath H 2 in the fasting state and in response to feedings containing lactose than noncolicky infants produce. This may represent increased lactose malabsorption, differences in colonic bacterial fermentation conditions, or differences in the handling of colonic gas produced.