Maltitol broken down by gut bacteria in men
What it found
In healthy men, most of a dose of maltitol was fermented by gut bacteria rather than digested by the body's enzymes, and it provided less energy than sugars like sucrose.
The study measured radioactive carbon from maltitol in breath, urine and faeces.
What they found
Studies in people
Carbon dioxide in breath
After the men took the labelled maltitol, radioactive carbon dioxide in their breath peaked about 3 hours later. Over 48 hours, 56% of the radioactivity was recovered in breath.
Hydrogen in breath
Breath hydrogen rose at 1 hour after the men took maltitol and peaked at 3.5 hours. Maltose, a regular sugar, did not raise breath hydrogen.
Other routes out
In 48 hours, 2.6% of the radioactivity came out in urine and 14.3% in faeces. Only 0.2% was recovered as methane in breath.
Blood sugar
Blood glucose levels did not change significantly in the 3 hours after the men took maltitol. There was a small peak at 90 minutes.
Animal and lab studies
Lab tests with faeces
When maltitol was mixed with faeces from 17 men in the lab, it was mostly used up by gut bacteria within 8 hours. About 14% of the radioactivity went into the bacteria and another 14% became carbon dioxide.
Other findings
Energy from maltitol
The authors say the energy available from maltitol is much lower than from digestible sugars such as sucrose. They argue that a previous estimate of about 90% energy use was too high.
What the authors conclude
“These results demonstrate that a greater part of ingested maltitol is fermented by intestinal microbes than is hydrolyzed by digestive enzymes.”
Also in their conclusions
- They conclude that a greater part of maltitol taken in is fermented by gut bacteria than is broken down by digestive enzymes.
- They state that although maltitol is broken down to carbon dioxide via gut bacteria, the available energy is much lower than that of digestible sugars such as sucrose.
- They advise that the bioavailable energy of maltitol should be markedly less than 90% of that of glucose.
How it was done
Maltitol is a sweetener that is thought to be less easily digested than sucrose and to cause a smaller rise in blood sugar. The authors wanted to find out exactly how the body handles maltitol, including how much is broken down by gut bacteria.
Six healthy men swallowed a single dose of 0.4 g of maltitol per kg of body weight that contained a radioactive label, and their breath, urine, faeces and blood were collected for 48 hours. In a separate test, 15 healthy men took 30 g of maltitol and their breath was collected for 10 hours to measure hydrogen.
What it can’t tell you
- This was a small study in healthy men, so the results may not apply to women, children, or people with different gut bacteria.
- The study measured how maltitol is broken down, not whether it has any long-term health effects.
- The radioactive label cannot show exactly which bacteria do the work or how maltitol affects the gut over time.
Who paid
- Authors work at
- University of Tokyo, Japan
The paper
- Title
- Metabolic fate of ingested [14C]-maltitol in man
- Type
- Study
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Oku T, Akiba M, Lee MH, Moon SJ, Hosoya N (1991). Metabolic fate of ingested [14C]-maltitol in man. Journal of nutritional science and vitaminology. doi:10.3177/jnsv.37.529Free full textPubMed 1802977DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error