Consequences of incomplete carbohydrate absorption from fruit juice consumption in infants

Background: Most infants consume fruit juices by 6 months of age. However, fruit juices containing sorbitol may be associated with carbohydrate malabs orption without clinical symptoms. We hypothesized that increased physical activity and metabolic rate may be associated with carbohydrate malabsorpti on. Methods: Physical activity and metabolic rate were determined in 14 healthy infants ([mean +/- SD] age, 5.1 +/- 0.8 months; weight, 7.8 +/- 1.1 kg; le ngth, 67 +/- 4.2 cm; and body fat, 26% +/- 5%) for 3 hours in a respiratory chamber. Seven were fed pear juice, and the other 7 were fed white grape j uice (120 mt) after a 2-hour fast. Pear juice contains sorbitol and a high fructose-glucose ratio, whereas white grape juice is sorbitol free and has a low fructose-glucose ratio. Carbohydrate absorption was determined by bre ath hydrogen gas analysis. The study was double-blinded. Results: When compared with the infants without carbohydrate malabsorption (peak breath hydrogen level <20 ppm above baseline), 5 of the 7 infants fed pear juice and 2 of the 7 infants fed white grape juice exhibited carbohyd rate malabsorption (peak breath hydrogen level greater than or equal to 20 ppm above baseline; P < .01). These infants also exhibited both increased p hysical activity (P < .001) and metabolic rate (P < .05) after juice consum ption in comparison with infants with normal carbohydrate absorption. When grouped according to the type of juice consumed, only infants fed pear juic e exhibited increases in physical activity (P < .01). Conclusions: Carbohydrate malabsorption is associated with increased physic al activity and metabolic rate in infants. Most of the infants who had carb ohydrate malabsorption consumed pear juice. Therefore, fruit juices contain ing sorbitol and high levels of fructose may not be optimal for young infan ts.