Guar gum, a water-soluble dietary fibre, is obtained from the seeds of the guar plant found on the Indian sub-continent and the US. Because of its high viscosity, the gum can be hydrolysed so that it can be used in quantities that infer a physiological effect, and is widely used in this form in beverages.
The new study, published in the Journal of Nutritional Biochemistry (Vol. 17, pp. 402-409) looked at the effects of a PHGG supplement to the diet of female mice with inflamed colons.
The researchers, led by Yoji Naito from the Kyoto Prefectural University of Medicine in Japan, added dextran sulphate sodium (DSS) to the drinking water of nine-week old mice to induce colitis. The mice were then divided into two groups - a control group, and atest group with the control diet supplemented with 5, 10, or 15 per cent PHGG (SunFiber, provided by Taiyo Kaguku).
After three weeks the scientists found that DSS ingestion had resulted in a shortening of the colon length in both control and test groups. However mice supplemented with PHGG had 15 per cent longer colons than the control mice.
Levels of the inflammatory marker, TNF-alpha, were also significantly reduced in the test group, compared to the control group. Supplementation with 5 per cent PHGG reduced TNF-alpha levels by 23 per cent. No significant difference was observed between the supplementation doses so the researchers concentrated their observations to the lowest dose group.
"Inhibition of TNF-alpha by PHGG-supplemented diet was accompanied by significant suppression of intestinal inflammation in vivo," wrote Naito.
"These data suggest that oral administration of PHGG may be an additional therapeutic strategy for inflammatory bowel disease," concluded the researchers.
The researchers said the further studies were needed to elucidate the underlying mechanism, but noted that previous suggestions of increased levels of Bacteroides in the gut were not observed in this study - other studies had identified PHGG as a prebiotic, boosting beneficial intestinal microflora populations.
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 (€m) in 2004, insoluble fibre dominates the market with $176.2m (€m), and $16.6m (€m) soluble.
But while Frost and Sullivan predicts overall growth in the US to $470m (€m) 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.