H2 excretion after ingestion of complex carbohydrates

Gastroenterology. 1987 Feb;92(2):383-9. doi: 10.1016/0016-5085(87)90132-6.


Malabsorption of fermentable material in a variety of foods was assessed by measurement of breath H2 excretion. Breath H2 increased well above that observed in fasting subjects after ingestion of 100 g of carbohydrate in oats, whole wheat, potatoes, corn, and baked beans. Rice caused only a minimal increase in H2 excretion and hamburger was associated with no increase. We estimated the malabsorption of fermentable material by comparing the H2 excretion for 9 h after ingestion of various complex carbohydrates with that after 10 g of lactulose. The mean malabsorption of fermented material after 100-g carbohydrate meals was 20 g for baked beans; 7-10 g for wheat, oats, potatoes, and corn; and 0.9 g for rice. Whole oats or whole wheat resulted in 2-5 times more H2 than did the refined flours. As purified fiber appeared to be a poor substrate for H2 production by fecal homogenates, we conclude that most complex carbohydrates, with the exception of rice, contain a good deal of fermentable material that escapes small bowel absorption and it seems likely that this fermentable material is malabsorbed starch.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Breath Tests
  • Dietary Carbohydrates / metabolism*
  • Fasting
  • Food
  • Humans
  • Hydrogen / analysis*
  • Hydrogen-Ion Concentration
  • Intestinal Absorption*
  • Intestine, Small / metabolism
  • Middle Aged
  • Time Factors


  • Dietary Carbohydrates
  • Hydrogen