Fruit juice malabsorption: not only fructose.

Malabsorption of free fructose, when ingested in excess over glucose, is considered a significant factor in apple juice induced diarrhoea. Absorption of the carbohydrates in fruit juices was investigated by means of the hydrogen breath test in 15 healthy children aged 2.2-6.4 years, consuming 15 ml kg-1 of each juice with a maximum of 375 ml. Incomplete absorption was found following the ingestion of apple juice (5/5), grape juice (10/10) and bilberry juice (8/10), although the last two contain equivalent concentrations of fructose and glucose. When the same tests were repeated after yeast treatment of the juices, which leads to major reductions in fructose and glucose contents, malabsorption was found to persist. No symptoms were observed following any of the tests. Our results suggest a significant role for other carbohydrates than fructose, possibly those originating from the fruit skin, with respect to fruit juice-induced breath hydrogen excretion.