Why does everyone's excrements smell the same?

A vegan’s solid waste has the same smell as a carnivore’s (allowing for unnoticeable differents). Same with farts. There’s a generic fart odor, regardless of the food the person has eaten. Roughly the same with vomit and piss and semen. Shouldn’t a person’s diet have a large effect on what leaves the body? Why does rotten yogurt smell the same as rotten bacon?

For some people asparagus makes pee smell different, but why don’t all foods do this?

I am going to have to disagree with your premise. Poop has many different odors. Disease can make a difference, too. C-diff has it own distinctive odor, for example

I don’t think that’s true. Else, why do most people not mind the smell of their own farts, but can’t stand the smell of farts from other people?

I also disagree with the premise.
One person’s farts and poop can smell noticeably different from one day to the next depending on diet and other factors. The difference between two or more different people would likewise vary.

panache45, I really don’t think you did the field work on this one before posting the question.
I challenge you to detail your research.

Very true. My wife is an RN and has requested that doctors order a test for C-diff many times due to something she smelled. She hasn’t been wrong yet.

If you were a dog, you wouldn’t ask that question.

Not all feces and flatus smell the same, but there are certain common compounds that we generally associate with the smell. Sulfur compounds contribute the most to the unpleasantness.

But I think rotten yogurt smells absolutely nothing whatsoever like rotten bacon.

I think some of this is psychological, similar to how you can’t tickle yourself. Otherwise, there would be some other people whose farts you don’t mind either, not just your own.

What’s with all the shitty threads nowadays?

yup. I’m in the “they all smell very different” camp, but I think the op was asking why there is a distinctive profile of what human feces generally smell like, and perhaps why they smell different for human than for dogs than for cats, say.

I’d guess some of it is bile. Some is probably other stuff we shed while we digest. Baby poop smells very different from adult poop. But that’s probably due to the all-milk diet.

Cute username response combo.

Yup, hydrogen sulfide gas and a compound called skatole, both of which are produced by the digestion of certain amino acids, the latter from tryptophan, whether the tryptophan comes from meat or from spinach.

On the subject of baby poop, in particular breast fed poops smell very different than formula fed poops. Not sure what exactly is the difference as the protein contents are very very similar. I suspect that has to do with particular oligosaccharides in breast milk that feed a particular microbiota more.

I agree the premise of the question is wrong. Feces (and flatulence) can smell very strongly, or can be relatively odorless, depending both on diet and on individual physiology.

This said, there are certain compounds that are typically produced as the result of digestion or manufactured by gut bacteria that give feces their typical smell. These may be produced as the result of the digestion of particular compounds, such as proteins, regardless of their source from meat or from vegetables. These compounds include indole, skatoles, thiols (mercaptans), and hydrogen sulfide gas.

Regarding the smell of urine, it’s the result of filtration of the blood by the kidneys so there’s not that many compounds that normally make it through. Most of the odor is from ammonia, and comes from nitrogen that results largely from the breakdown of proteins.

I will never read his posts in the same way again…


Drink a bottle of Bourbon and your shit will smell sweet.

Yep, I gotta disagree with the OP. For example, my shit doesn’t stink.

And it will stain the sheets.

I have to disagree with the OP’s premise. Other people’s shit does NOT smell like roses.

And what about the different odours of male and female poop?

I don’t shit. My digestive system is 100% efficient at mass to energy conversion.