High-fibre diet reduces GI toxicity in patients undergoing pelvic radiotherapy
Following a high-fibre diet during pelvic radiotherapy appears to lessen gastrointestinal (GI) toxicity both acutely and at 1 year compared with a habitual-fibre diet, a recent study has found.
Researchers randomized patients to either low-fibre (≤10 g nonstarch polysaccharide [NSP]/day; n=55), habitual-fibre (control; n=55) or high-fibre (≥18 g NSP/day; n=56) diets to assess the potentially beneficial mechanisms of fibre in preventing GI toxicity during pelvic radiotherapy. Participants received individualized counseling at the start of radiotherapy to achieve these targets.
The difference between groups in the change in the Inflammatory Bowel Disease Questionnaire–Bowel Subset (IBDQ-B) score between the starting and nadir (worst) score during treatment was the main outcome. Other measures included macronutrient intake, stool diaries and faecal short-chain fatty acid concentrations.
There were significant between-group differences in terms of fibre intakes (p<0.001). Although nonsignificant difference was observed between groups in the change in IBDQ-B scores between the start and nadir (p=0.093), the change in score between the start and end of radiotherapy was smaller in the high-fibre group (mean±SD, ‒3.7±12.8) than in the habitual-fibre group (‒10.8±13.5; p=0.011).
The difference in IBDQ-B scores at 1 year after radiotherapy was significant between the high-fibre (0.1±14.5) and the habitual-fibre (‒8.4±13.3) groups (p=0.004). There were no significant differences in stool frequency or form or in short-chain fatty acid concentrations.
Furthermore, significant decreases in energy, protein and fat intake were observed in the low- and habitual-fibre groups only.
“Restrictive, nonevidence-based advice to reduce fibre intake in this setting should be abandoned,” according to researchers.