I don't exactly understand it either, but apparently that's the case. My doctor mentioned this during one of my appointments last year (most people "resorb" a large percentage of hydrogen that is produced in the GI tract).From that article (which is good- thanks for posting it Moises and Jillywindy):I just don't understand the mechanism by which methane could be trapped but hydrogen must always escape. But it could be that way. Just doesn't seem logical to me, but then bodies don't always do the logical.
...hence the hydrogen breath test. I suppose. ??The amount of hydrogen gas produced depends not only on the type and quantity of the various substrates but also on the type of colonic flora. Bacteria vary in their capacity to convert carbohydrate to hydrogen. Furthermore, only about 10% of the hydrogen produced is actually expelled rectally. Some of the hydrogen is consumed by other colonic bacteria, a phenomenon that may partially explain unsuccessful attempts at treating flatulence with antibiotics. A large portion of the hydrogen is absorbed into the portal blood for eventual excretion by the lungs. This excretory pathway has enabled breath analysis to be used to study intestinal gas production.