Psyllium provides seriously impressive dietary fibre content - providing a massive 80% soluble to 20% insoluble fibre, compared with grains which provide mainly the insoluble 'roughage' kind. Once inside your beautiful bod, it absorbs liquid and expands into a gel like consistency, basically becoming a broom for your insides.
Note: Psyllium absorbs liquid so it is very important to drink plenty of water when taking this herb.