Little is known about the gastrointestinal effects of ingesting maltitol in chocolate. This study was designed to determine whether it leads to increased gastrointestinal symptomatology and if that symptomatology is dose related. It was also designed to discover whether breath hydrogen excretion in response to maltitol is dose related. In a double-blind, crossover study, 20 healthy volunteers aged 18-24 y ingested 100 g chocolate containing 40 g sucrose, 10 g sucrose plus 30 g maltitol or 40 g maltitol after fasting (abstinence from food and liquids from 2200 h on the night before chocolate consumption) and not fasting. There was no difference in symptomatology between fasting and nonfasting periods, and consumption order had no effect on symptomatology. Relative to ingestion of sucrose, 30 g maltitol caused no significant difference in symptoms, but 40 g resulted in more mild borborygmi (P < 0.05) and mild flatulence (P < 0.01) but not moderate or severe symptoms. Neither 30 nor 40 g maltitol caused significantly greater laxation than sucrose ingestion (P > 0.05). In a separate study, 10 healthy volunteers aged 18-24 y ate the same test products before breath H2 testing; 40 g maltitol in chocolate caused a greater total breath H2 excretion compared with 30 g maltitol (P < 0.05) or sucrose (P < 0.01). Total breath hydrogen excretion was also greater with 30 g maltitol compared with sucrose (P < 0.05). This dose-related response was consistent with the lower symptomatology after ingestion of 30 vs. 40 g maltitol. We have shown that 30 g maltitol in chocolate causes no significant symptomatology in young adults; however, 40 g caused mild borborygmi and flatus but no increased laxation. An increased breath H2 response indicates colonic fermentation of this polyol.