The effect of partially hydrolyzed guar gum on preventing influenza infection.

Background & Aims: Seasonal influenza infection in hospitals is a serious problem, and infection prevention is important. We examined retrospectively the effect of prebiotics using partially hydrolyzed guar gum (PHGG) in the prevention of influenza infection.

Methods: Among the patients who were admitted to Hokusei Hospital between April 2017 and March 2019, 522 patients consuming food orally (492 in the convalescent rehabilitation ward and 30 in the long-term care ward) were included in this single-center retrospective cohort study. Patients were divided into two groups: a group continuously taking PHGG (PHGG group; 172 patients in the convalescent rehabilitation ward and 16 patients in the long-term care ward) and a group not taking PHGG (non-PHGG group; 320 patients in the convalescent rehabilitation ward and 14 patients in the long-term care ward). The incidence of influenza during hospitalization, stool pH, and Bristol Stool Form Scale (BSS) at 2 months after admission (2 months after the start of PHGG intake in the PHGG group) were compared between the two groups. In addition, stool pH and BSS were compared between patients who developed influenza and those who did not.

Results: A total of 24 patients developed influenza. These patients were from the non-PHGG group (12 in the convalescent rehabilitation ward and 12 in the long-term care ward), with a significant difference in the incidence of influenza between these two sub-groups (p < 0.001). The non-PHGG group had more patients with high stool pH (90th percentile or higher) (p = 0.097, not clinically significant, in the convalescent rehabilitation ward and p < 0.001 in the long-term care ward). This group also had more patients with very poor BSS (score 1 or 7) (p = 0.045 in the convalescent rehabilitation ward and p < 0.001 in the long-term care ward). In addition, patients with influenza onset had high stool pH and very poor BSS regardless of their wards.

Conclusion: The incidence of influenza was found to be different between patients with and without taking PHGG. Stool pH and BSS were different between patients with and without PHGG intake and those with and without influenza onset, suggesting that PHGG can affect the intestinal environment and thus contribute to reducing the incidence of influenza.