Six healthy male subjects were given a single oral dose of 0.4g of maltitol per kg body weight containing [U-¹⁴C]-maltitol (50μCi) and their breath, urine, feces and blood were collected at appropriate intervals for 48h to measure the recovery of administered radioactivity. Further, to measure breath hydrogen, 15 healthy male subjects ingested 30g of maltitol and samples of their breath were collected for a 10-h period. The expired ¹⁴C0₂ showed a wide peak about 3 h after ingestion and 56% of the administered radioactivity was recovered in 48 h. An additional 0.2% of administered radioactivity was recovered as expired ¹⁴CH₄, 2.6% in urine and 14.3% in feces, respectively. The obvious increase of breath hydrogen was detected at 1 h after maltitol ingestion and then a big peak at 3.5h, whereas maltose ingestion did not increase breath hydrogen. Both excretion profiles of breath ¹⁴C0₂ and hydrogen coincided well. These results demonstrate that a greater part of ingested maltitol is fermented by intestinal microbes than is hydrolyzed by diges-tive enzymes. Although maltitol is catabolized to carbon dioxide via intestinal microbes, the available energy is much lower than that of digestible sugars such as sucrose.