# Why does everyone's excrements smell the same? **URL:** \ **Category:** Factual Questions\ **Created:** [December 4, 2014, 12:51pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308 "2014-12-04T12:51:16Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [December 4, 2014, 7:03pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/21 "2014-12-04T19:03:41Z")
> [@Bert\_Nobbins](#): > > And what about the different odours of male and female poop? Females poop? I’m guessing it’s pink and smells like roses and bubble gum. ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [December 4, 2014, 7:16pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/22 "2014-12-04T19:16:40Z")
My cat’s farts smell like cat food. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [December 4, 2014, 11:00pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/23 "2014-12-04T23:00:35Z")
> [@cochrane](#): > > I don’t shit. My digestive system is 100% efficient at mass to energy conversion. So basically you’re a fusion reactor? 😉 ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [December 4, 2014, 11:23pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/24 "2014-12-04T23:23:53Z")
> [@cochrane](#): > > I don’t shit. My digestive system is 100% efficient at mass to energy conversion. > [@CookingWithGas](#): > > So basically you’re a fusion reactor? 😉 Matter-antimatter more like. You want to be a LONG way away (like the other side of the planet) if he ever does let one go! ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 5, 2014, 12:14am UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/25 "2014-12-05T00:14:48Z")
😕 “C-diff”? ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [December 5, 2014, 12:18am UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/26 "2014-12-05T00:18:57Z")
> [@Leo\_Bloom](#): > > 😕 “C-diff”? It’s short for a bacteria (C. difficile) that can take over the gut, especially in people taking antibiotics. Unlike the normal bacterial colonies, this one does not play nice. ---
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [December 5, 2014, 1:05am UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/27 "2014-12-05T01:05:54Z")
My shit don’t smell. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [December 5, 2014, 4:39am UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/28 "2014-12-05T04:39:53Z")
> [@dracoi](#): > > It’s short for a bacteria (C. difficile) that can take over the gut, especially in people taking antibiotics. Unlike the normal bacterial colonies, this one does not play nice. Apparently the liquid feces produced by someone with C. Diff also look distinctive visually. ---
**Author:** ![Some\_Call\_Me.Tim](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@Some\_Call\_Me.Tim](https://boards.straightdope.com/u/Some_Call_Me.Tim)\ **Post date:** [December 5, 2014, 4:55am UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/29 "2014-12-05T04:55:25Z")
> [@panache45](#): > > For some people asparagus makes pee smell different, but why don’t all foods do this? Actually, this is false. Asparagus has a similar effect on the pee of anyone who eats it. However, only a fraction of the population has the gene that allows their nose to _smell_ that particular scent. ---
**Author:** ![shiftless](https://avatars.discourse-cdn.com/v4/letter/s/e9c0ed/32.png) [@shiftless](https://boards.straightdope.com/u/shiftless)\ **Post date:** [December 5, 2014, 2:18pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/30 "2014-12-05T14:18:31Z")
> [@Some\_Call\_Me.Tim](#): > > Actually, this is false. Asparagus has a similar effect on the pee of anyone who eats it. However, only a fraction of the population has the gene that allows their nose to _smell_ that particular scent. Is this really true, that only a small number of people can smell the hideous after effects of asparagus? Because my wife loves asparagus so it appears in my food a lot. It only takes a few minutes for the smell to appear and it is so strong I suspect others might be offended. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [December 5, 2014, 2:27pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/31 "2014-12-05T14:27:33Z")
Hmm, it’s a strong smell, but I’ve never found it especially offensive. I am always surprised at how little asparagus it takes, and how quickly the smell manifests itself, though. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [December 5, 2014, 2:38pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/32 "2014-12-05T14:38:58Z")
Actually there is [BOTH](http://chemse.oxfordjournals.org/content/early/2010/09/27/chemse.bjq081.full) a variation in the production of the smelly metabolites after eating asparagus _and_ in the ability to perceive them. It’s nearly 50/50. > [@](#): > > … When humans eat asparagus, some people report a distinct odor afterward from their urine. About 8% of the subjects studied herein did not produce this characteristic asparagus odor in sufficient concentration to be detected by the methods used here. … About 6% of subjects are unable to detect asparagus odor, and we ruled out generalized smell loss in these subjects by assessing their response to a second odorant. Therefore, the most likely explanation is that these individual differences in odor detection are a specific anosmia. … The reduced ability to smell the asparagus metabolites in urine appears to be related to a single nucleotide polymorphism near the olfactory receptor gene OR2M7. This genotype–phenotype relationship is similar to other alleles in olfactory receptors that reduce the ability to smell androstenone (Keller et al. 2007) and isovaleric acid (Menashe et al. 2007). … The major determinant of individual differences in asparagus odor production in urine remains unknown … the production of the asparagus metabolites was not tightly related to the ability to smell them. Reducing ignorance one pisspot at a time! ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [December 5, 2014, 2:45pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/33 "2014-12-05T14:45:55Z")
Neat, **DSeid**. The issue had come up in my family but, while we’d been able to verify that some of us did indeed not produce the Famous Asparagus Smell, attempts at verifying whether the non-producers were some sort of mutants or aliens from outer space had thus far failed. Looks like they’re merely part of a 1-in-12 minority. ---
**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\ **Post date:** [December 5, 2014, 8:10pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/34 "2014-12-05T20:10:11Z")
> [@Colibri](#): > > … These compounds include indole, skatoles, thiols (mercaptans), and hydrogen sulfide gas… I read this as “mercotans” and thought I’d figured out **QtheM** ’s username. ETA: that’s an interesting study, **DSeid** , and thanks for sharing it. The last sentence in your quote – that the ability to produce, and the ability to smell, the compounds is “not tightly related” – fascinates me. You’d think for evolutionary reasons they’d have gotten linked. ---
**Author:** ![Donnerwetter](https://avatars.discourse-cdn.com/v4/letter/d/b2d939/32.png) [@Donnerwetter](https://boards.straightdope.com/u/Donnerwetter)\ **Post date:** [December 5, 2014, 9:02pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/35 "2014-12-05T21:02:22Z")
This reminds me of a book about the French war in Indochina in the late 1940s. The author describes the actions of a platoon of the Foreign Legion in hot pursuit of a band of Vietnamese guerillas in the jungle. There is one soldier in the platoon who is able to detect the smell of human feces over considerable distances and who can also tell how long ago the poop was produced. The platoon leader radios the information to his HQ. When the Lieutenant is asked by his CO how he is able to obtain such valuable intelligence about the enemy’s movements, he answers: “I’d rather not say. You wouldn’t believe it, anyway” ---
**Author:** ![Mona\_Lisa\_Simpson](https://avatars.discourse-cdn.com/v4/letter/m/ce7236/32.png) [@Mona\_Lisa\_Simpson](https://boards.straightdope.com/u/Mona_Lisa_Simpson)\ **Post date:** [December 6, 2014, 3:54am UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/36 "2014-12-06T03:54:24Z")
:eek:Geriatric nurse here. I have changed a lot of diapers. BMs smell different person to person, meal to meal. Poop from puree eaters smells different than those on solids. I once was the only person on my floor with a shift rotation that meant I worked on a particular day that served borscht and cabbage rolls for lunch followed by some kind of spinach dish with supper. The results the next day were very–um… fragrant and colourful. :eek: As for urine I can usually tell if someone has a Urinary tract infection. (Restless person becomes very sedentary or vice versa) So if at 0500 a person in my care hasn’t slept much, is calling out, is climbing out of bed and his or her brief is soaked with dark urine that smells very strongly (often either cat box at the Crazy Cat Lady’s house, or rancid peanut butter) I will set up a collection system and email or voicemail the doctor to order specimens for urinalysis and culture & sensitivity. 😃 I once worked with a care aide who could unofficially diagnose a UTI by walking in a room. I honestly felt sorry for him; his sense of smell was too acute. (As for other secretions… I dated vegans. I can tell the difference. 😉 ) ---
**Author:** ![zweisamkeit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zweisamkeit/32/4360_2.png) [@zweisamkeit](https://boards.straightdope.com/u/zweisamkeit)\ **Post date:** [December 6, 2014, 4:11pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/37 "2014-12-06T16:11:11Z")
> [@shiftless](#): > > Is this really true, that only a small number of people can smell the hideous after effects of asparagus? Because my wife loves asparagus so it appears in my food a lot. It only takes a few minutes for the smell to appear and it is so strong I suspect others might be offended. Everyone I know who loves asparagus can also smell asparagus pee. It’s just not a big deal; certainly not enough to avoid eating asparagus. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [December 6, 2014, 4:21pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/38 "2014-12-06T16:21:51Z")
> [@Mona\_Lisa\_Simpson](#): > > :eek:Geriatric nurse here. I have changed a lot of diapers. BMs smell different person to person, meal to meal. Poop from puree eaters smells different than those on solids. I once was the only person on my floor with a shift rotation that meant I worked on a particular day that served borscht and cabbage rolls for lunch followed by some kind of spinach dish with supper. The results the next day were very–um… fragrant and colourful. :eek: Just to be clear, since you seem to be our resident feces expert :): Apart from asparagus and disease, is the difference in odor of a person’s feces almost all due to differences in their diet, or are there still significant person to person differences even for healthy people with the same diet? ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 6, 2014, 6:11pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/39 "2014-12-06T18:11:40Z")
> [@Nava](#): > > Neat, **DSeid**. … +1 …asparagus, tinged with ultramarine and rosy pink which ran from their heads, finely stippled in mauve and azure, through a series of imperceptible changes to their white feet, still stained a little by the soil of their garden-bed: a rainbow-loveliness that was not of this world. I felt that these celestial hues indicated the presence of exquisite creatures who had been pleased to assume vegetable form, who, through the disguise which covered their firm and edible flesh, allowed me to discern in this radiance of earliest dawn, these hinted rainbows, these blue evening shades, that precious quality which I should recognise again when, all night long after a dinner at which I had partaken of them, they played (lyrical and coarse in their jesting as the fairies in Shakespeare’s Dream) at transforming my humble chamberpot into a bower of aromatic perfume.” –not James Joyce ---
**Author:** ![Son\_of\_a\_Rich](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/son_of_a_rich/32/5439_2.png) [@Son\_of\_a\_Rich](https://boards.straightdope.com/u/Son_of_a_Rich)\ **Post date:** [December 6, 2014, 7:01pm UTC](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308/40 "2014-12-06T19:01:36Z")
“Why does everyone’s excrements smell the same?” How many different people’s poop did you sample to come to this conclusion? [Previous page](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308.md?page=1) [Next page](https://boards.straightdope.com/t/why-does-everyones-excrements-smell-the-same/706308.md?page=3)