IMPACT OF DIETARY CEREAL ON NUTRIENT ABSORPTION AND FECAL NITROGEN LOSS IN FORMULA-FED INFANTS

Study objective: To determine the capacity of infants to digest and absorb rice cereal and to determine the effect of cereal feeding on total energy and nitrogen absorption. Setting: Subjects' residences and the Texas Children's Hospital Clinical Research Center, Houston. Patients: Eight healthy 1-month-old bottle-fed infants. Interventions: Infants were fed their usual formula for 3 days. For the subsequent 6 days, they received 4 gm of rice cereal, labeled with carbon 13, per 30 ml of the formula. Measurements and main results: Fecal balance studies were performed for a 72-hour period while the infants received only formula and again during the last 3 days of cereal feeding. Breath samples for hydrogen measurement were collected before and after the cereal feeding. Nutrient intake was measured and stools were analyzed for C-13 abundance, energy, nitrogen, fiber content, and bacterial mass. Cereal absorption was 88 +/- 9% (mean +/- SD). Despite a significant increase in energy and nitrogen intake from cereal feeding, the coefficient of absorption fell (energy: 97% to 90%, p = 0.048; nitrogen: 94% to 74%, p = 0.009). Fecal dry weight increased after the cereal feeding (p = 0.004), primarily as a result of a sevenfold increase in fecal bacterial mass (p = 0.002). Fecal nitrogen increased primarily because of incorporation of nitrogen into bacteria. No differences were detected in breath hydrogen as a consequence of formula feeding versus formula-cereal feeding. Conclusions: Although cereal was relatively well-absorbed in this group of infants and increased their intakes of energy and nitrogen, it did not increase the coefficients of energy and nitrogen absorption. Cereal feeding increased fecal bacterial mass and bacterial nitrogen.