We haughty Brits have a much fancier name for Psyllium: it's called ispaghula here but is the same thing. It's typically sold in single-dose sachets (the big brand is Fybogel), flavoured with orange or something like that. The instructions tell you that it should be stirred into a bit of water and drunk immediately at the same time as food. I can attest to the fact that if you don't glug it straight away you'll have the devil of a job washing the mucilaginous dregs out of your glass. In water, the psyllium/ispaghula husk forms a thickening gloop that is high in soluble fibre, which helps to soften stools and makes it easier to eliminate them. It's good stuff, but, like everything, it may not be for everyone, so listen to the Mrrzy doc rather than the Mudcat doc.