Randomized Clinical Study

Partially Hydrolyzed Guar Gum (PHGG) Versus Placebo in the Treatment of Patients With Irritable Bowel Syndrome

E. Niv; A. Halak; E. Tiommny; H. Yanai; H. Strul; T. Naftali; N. Vaisman


Nutr Metab. 2016;13(10) 

In This Article


One-hundred and eighty-six patients underwent screening for this study. Of them, 121 patients fulfilled the inclusion criteria, signed informed consent and underwent a blind randomization into either the 6 g PHGG group or the placebo group. During the two-week run-in-period, 13 patients dropped out of the study (two patients due to travel plans, eight withdrew consent, and three were unwilling to stop probiotics). The remaining 108 patients attended the second visit of the study, provided baseline IBS parameters and started the administration of the study product/placebo. All these 108 patients were included in the intention-to-treat analysis. Table 1 presents the demographic data of these patients and their IBS baseline parameters. The PHGG group including 49 patients and the placebo group included 59 patients. The patients in both groups were of similar age (46.2±19.2 and 40.8±15.6 years for the PHGG and placebo groups, respectively, P = 0.1). IBS was longstanding for most of the participants, with a mean duration of 15.2±14.9 years in the study group and 13.4±12.4 years in the placebo group, P = 0.5. The gender distribution was similar in both groups (female predominant). Most of the patients in both groups had a mixed type of IBS (24/49 patients in the study group and 40/59 patients in the placebo group). Table 1 demonstrates the severity of IBS symptoms at baseline. The PHGG group had a more severe degree of IBS than the placebo group in terms of abdominal pain (31±15.6 versus 21.6±16.4), gasses (38.3±15.2 versus 32.5±13.5) and total severity score (307±85 versus 267.9±115.7) (P = 0.003, P = 0.036 and P = 0.046, respectively). Of course, the design of prospective randomized double-blind placebo controlled study could not allow us to predict this kind of distribution of patients. To overcome this, the dynamic changes in all the scores during the study were calculated as a difference from the baseline and not as an absolute value.

The patients took the study product/placebo for 12 weeks. They were then instructed to stop the administration of the products and entered four weeks of follow-up. A total of 92 patients completed one month of treatment, 78 patients completed two months, 68 patients completed three months and 41 patients completed three months of treatment and one month of follow-up. The rate of dropouts was significantly higher among patients in the placebo group (29 patients) compared to the PHGG group (11 patients) (49.15% versus 22.45%, respectively, P = 0.01). During the study, nine PHGG patients and nine placebo patients reported experiencing mild side effects, such as abdominal pain, gasses, diarrhea, heartburn, nausea. It was impossible to conclude if these side effects were related to PHGG because of their similarity to IBS symptoms. The side effects were mild and discontinued immediately after the stop of PHGG/placebo.

Table 2 presents the results of the effect of PHGG/placebo on IBS symptoms in our study over the 12 weeks of treatment, and Fig. 1 demonstrates the same results graphically. The assessment was performed based on intention-to-treat analysis. Delta between the change and the baseline for all the scores was chosen to be evaluated and not the absolute values of scores because the PHGG group appeared to have more severe IBS disease compared to the placebo group. The results of the study clearly demonstrated that the PHGG group had a significant improvement in bloating score (−4.1±13.4 versus −1.2±11.9) and bloating+gasses scores (−4.3±10.4 versus −1.12±10.5) compared to the placebo group (P = 0.03 and P = 0.035, respectively). This effect was consistent throughout the 12-week study period, as is apparent from the P values of interaction between the time and groups (P = 0.027 and P = 0.03 for bloating and bloating+gasses scores, respectively). After four weeks since the cessation of PHGG ingestion, the bloating and gasses scores started to arise again, although the difference was not significant (P = 0.9 and P = 0.83, respectively), indicating that the positive effect of PHGG did not diminish after four weeks of follow-up. Additionally, Table 2 demonstrates that PHGG had no advantage over the placebo regarding other IBS symptoms, such as abdominal pain (−3.4±11.9 versus −2.8±10.8), stool frequency (−0.8±5.1 versus −0.4±4.1), total severity score (−64.8±102.3 versus −53.9±86.7) and QOL (−7.8±20.7 versus −9.1±14.3) (P = 0.334, P = 0.713, P = 0.421, and P = 0.788, respectively). The net placebo effect resulted in a 20.1% improvement in the total severity score for the patients in the placebo group.

Figure 1.

Dynamic changes in IBS parameters over 3 months of treatment expressed as delta from the baseline values

Because the score of stool frequency has different meanings in patients with diarrhea-predominant and constipation-predominant IBS, the analysis of this score was performed separately for the patients with these two disease types. PHGG intake did not decrease the stool frequency in diarrhea-predominant patients nor did it increase stool frequency in constipation-predominant patients compared to the placebo group. However, a proper statistical evaluation could not been performed because of the relatively small number of patients in the groups with these types of IBS.