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Are there any studies or general information on the composition of human feces?

I'd specifically like to know the percentage of carbohydrates and amino acids relative to the amount that was ingested in diets of various types and amounts.

Any additional facts are also welcome.

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This is a bit hard because the usual composition statements are a combination of different types of molecules.

Most of faeces are, by dry weight, bacteria (30%), undigested food and fiber (30%), fat (10%-20%), inorganic matter( 10-20%), other protein(2-3%). (reference)

As you can see the bacterial portion contains proteins (amino acids) and other types of molecules. the inorganic matter includes bilins which are part of the used up hemoglobin from red blood cells which have been retired.

There's also a lot of variation from one sample to the next - 10% seems pretty common here as you can imagine). What makes faeces so dangerous is the bacterial portion, which can pose quite a health risk.

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