Flatulence in public can be embarrassing, especially if you are locked in, say, in a concert hall. I don't find it difficult to plug the release for a while. The pressure usually drops after a few minutes. However I wonder what happens to the obnoxious gases. Are they released at a rate below the detection level of most human noses or are they adsorbed in solid waste? I did some internet searches, but the research papers usually deal with methane, which is irrelevant because it has no odor.

1 Answer 1


They are mainly certain sulfur compounds that cause smelly gas (Gut, BMJ Journals):

...organic sulphides of bacterial origin, primarily methanethiol, dimethyl disulphide, and dimethyl trisulphide, were the primary malodorous compounds elaborated by faeces.

The cells of the large intestinal lining can break down hydrogen disulfide into dimethyl disulphide (PubMed), "which...probably plays little part in flatus malodour" (Gut, BMJ Journals). This means that holding gas would give hydrogen dioxide more time to break down and thus reduce its smell.

Avoiding foods high in sulfur (meat, fish, almonds, dates, broccoli, cauliflower, Brussels sprouts, cabbage) can decrease the smell of the gas (Gicare).

Ammonia can also give odor to the gas (PubMed). Apparently, a large percent of ammonia can be absorbed in the colon. (Camridge.org, 1984)

So, theoretically, holding back gas could reduce the smell of the flatulence.

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    I find the statement "you can't really prevent flatulence by holding gas" not convincing. This is the question! Nov 26, 2018 at 14:29
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    As often happens, after phrasing a topic carefully, you start thinking about it more methodically. I believe the key distinction is between permanent gases (at body temperature), like methane, CO2, H2, N2, and vapours, i.e. liquids or solids with a noticeable vapour pressure. Most odors are of the latter kind. Vapours will only exits as long as there are permanent gases. Hence if permanent gases can be removed from the rectum by dissolving in blood and releasing in breathing, the driving force of flatulence is gone.. Nov 26, 2018 at 14:36
  • It seems very likely that the gasses are absorbed into blood stream, just in physical principle, just very unlikely that the amount generated is in that much of a relation to what will be just expelled eventually. Nov 26, 2018 at 15:00
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    @mathieuvanrijswick You seem to have read a different wikipedia article than I did, and a gas doesn't need to be the main component to be the smelly component. Not sure what relevance your classification of ammonia as a vapour has.
    – Carey Gregory
    Nov 26, 2018 at 16:20
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    Gas smell comes mainly from sulfur compounds and ammonia. I edited my answer and, apparently, there is some logic by which holding back gas could reduce its smell.
    – Jan
    Nov 26, 2018 at 17:11

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