Physiological means IBS has an organic or biological basis as opposed to a psychological or mental basis. There isn't a cure for IBS. So hypnosis and meditation/relaxation cannot cure IBS. They are techniques for managing symptoms just like diet and cognitive behavior therapy which aren't cures either.
Consider the article linked to in the last posting in this thread. Cells were collected from the colon of IBS-D, IBS-C and normal individuals from biopsies. Extracts from these cells were applied to nerves from the gut. The extract from normal individuals did not cause the nerve cells to trigger while extracts from IBS-D and IBS-D individuals did. In other words there was something produced by IBS suffers that stimulated the colonic nerves. Further investigation revealed organic materials (histamine, serotonin and proteases) from the cells IBS suffers were causing the nerve cells to trigger. No mental or psychological processes were involved. Similarly, biopsies from the colon of individuals with post infectious IBS revealed localized micro-inflammation. In other words there was physiological or organic damage to the colon cells.
The brain-gut dysfunction in IBS is an organic or biological problem in the way the gut and brain communicate. Needless to say mental processes can affect the brain-gut communication but they don't cause the underlying IBS.
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS