

We don’t absorb everything completely, so some passes through unabsorbed. Some are passed via bile or mucous production, like manganese, copper, and zinc. Others are passed via urine. Some are passed via sweat. Selenium, when experiencing selenium toxicity, will even pass through your breath.
Other than the last one, most of those eventually end up going down the drain, either in the toilet, down the shower drain, or when we do our laundry. Though some portion ends up as dust.
And to be thorough, there’s also bleeding as a pathway to losing nutrients, as well as injuries (or surgeries) involving losing flesh, tears, spit/boogers, hair loss, lactation, finger nail and skin loss, reproductive fluids, blistering, and mensturation. And corpse disposal, though the amount of nutrients we shed throughout our lives dwarfs what’s left at the end.
I think each one of those are ones that, due to our way of life and how it’s changed since our hunter gatherer days, less of it ends up back in the nutrient cycle.
But I was mistaken to put the emphasis on shit and it was an interesting dive to understand that better. Thanks for challenging that :)
Technically they all end up up someone’s ass when used properly.