My understanding is that unbleached paper/cardboard is just cellulose and lignin, both of which are 100% indigestible insoluble fiber.
I think papier mache glue is made entirely of cellulose also (?) and is non toxic.
I am not getting enough insoluble fiber in my soylent, it is making my stool sticky. I did not have this problem with almond flour in the recipe but my protein source has all the phosphorus I need and the almond flour would be too much… it is also far too expensive an ingredient.
My soylent is made to be ketogenic, this is why I am having such problems with insoluble fiber sources. I tried coconut flour but it didn’t seem to help my stool consistency at all, it scratches my throat and makes it feel dry. Adding more psyllium does not help, presumably because it is mostly soluble. I tried sunflower seeds and pumpkin seeds, the texture and taste in the mix was unpleasant and they gave me stomach aches eating them separately. I can still try swapping the flaxseed oil for flaxseed meal/flour but I hear complaints about the taste of these and am still curious about the other options.
If paper is OK, what about newspaper? Would the ink be a problem?
I realise it may seem stupid to be asking these questions but paper is just wood fiber as far as I know, so I do not think it is really such a terrible idea… but it’s always worth checking.