Sufferers of irritable bowel syndrome (IBS) assigned to receive a soluble fibre supplement (psyllium) experienced a 90 point reduction in the severity of their symptoms, almost double the levels observed in the placebo group.
Reductions of 58 points in the severity of symptoms in the group assigned bran were noted, but this group experienced a high level of early drop-out following a worsening of IBS.
“In this randomised trial in primary care patients with irritable bowel syndrome, psyllium resulted in a significantly greater proportion of patients reporting adequate relief of symptoms compared with placebo supplementation,” wrote the researchers in the British Medical Journal.
The precise numbers of IBS suffers in the US are not known, as many people with mild symptoms do not consult a physician, but it is believed to be between 15 and 30 million.
The long-term condition, from which more women suffer than men, involves abdominal discomfort accompanied by diarrhoea or constipation. Although it is not life threatening and dose not lead to other, more serious health conditions, IBS is untreatable. At present, intervention involves management of symptoms.
Study details
Led by Dr C Bijkerk from the University Medical Center Utrecht, the researchers recruited 275 IBS sufferers aged between 18 and 65 and randomly assigned them to one of three groups: The first received daily supplements of soluble fibre (10 g psyllium), the second group received insoluble fibre (10 g bran), and the third group received placebo (10 g rice flour) for three months.
As the name suggests, soluble fibres can dissolve in water and are found in fruit and vegetable. On the other hand, insoluble fibres contain cellulose, hemicellulose and lignin and cannot be dissolved in water, and are commonly associated with cereals.
In Europe and Japan, soluble fibre has the greater market share than insoluble. In the US, where the entire fibre market was worth $192.8m (€151.0m) in 2004, insoluble fibre dominates the market with $176.2m (€138.0m), and $16.6m (€13.0m) soluble.
But while Frost and Sullivan predicts overall growth in the US to $470m (€369m) by 2011, the soluble fibre sector is expected to increase by almost twice the compound annual growth rate (CAGR) compared to insoluble fibre - 26.3 per cent compared to 13.1 per cent.
Only 64, 56, and 56 per cent of the participants of each group finished the study. Of these, the severity of IBS symptoms decreased by 90 points in the psyllium group, compared with 49 and 58 points in the placebo and bran groups, respectively.
The researcher did not note any differences between the groups with respect to their so-called ‘quality of life’.
Source: British Medical Journal
2009; Volume 339:b3154, Published 27 August 2009, doi:10.1136/bmj.b3154
"Soluble or insoluble fibre in irritable bowel syndrome in primary care? Randomised placebo controlled trial"
Authors: C.J. Bijkerk, N.J. de Wit, J.W.M. Muris, P.J. Whorwell, J.A. Knottnerus, A.W. Hoes