If the language doesn't deter you, have a look here
I've seen this 3-parts French documentary a few months ago on the Arte channel. We had to wait for a couple years to watch it, as the main TV channels considered it too risqué to air. Yet it is very well made and informative.
Part of the documentary is devoted to a Japanese scientist, who's refining a technology to extract nutriments from, well, plain human shit. He claims shit to be very rich in good proteins, and makes steak from shit and soy. He also claims his steaks taste good, almost like meat (athough I don't remember which kind of meat).
Soylent Brown anyone?