Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

Background: Therapeutic radiotherapy is an important treatment of pelvic cancers. Historically, low-fiber diets have been recommended despite a lack of evidence and potentially beneficial mechanisms of fiber.Objective: This randomized controlled trial compared low-, habitual-, and high-fiber diets for the prevention of gastrointestinal toxicity in patients undergoing pelvic radiotherapy.Design: Patients were randomly assigned to low-fiber [≤10 g nonstarch polysaccharide (NSP)/d], habitual-fiber (control), or high-fiber (≥18 g NSP/d) diets and received individualized counseling at the start of radiotherapy to achieve these targets. The primary endpoint was 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. Other measures included macronutrient intake, stool diaries, and fecal short-chain fatty acid concentrations.Results: Patients were randomly assigned to low-fiber (n = 55), habitual-fiber (n = 55), or high-fiber (n = 56) dietary advice. Fiber intakes were significantly different between groups (P < 0.001). The difference between groups in the change in IBDQ-B scores between the start and nadir was not significant (P = 0.093). However, the change in score between the start and end of radiotherapy was smaller in the high-fiber group (mean ± SD: -3.7 ± 12.8) than in the habitual-fiber group (-10.8 ± 13.5; P = 0.011). At 1-y postradiotherapy (n = 126) the difference in IBDQ-B scores between the high-fiber (+0.1 ± 14.5) and the habitual-fiber (-8.4 ± 13.3) groups was significant (P = 0.004). No significant differences were observed in stool frequency or form or in short-chain fatty acid concentrations. Significant reductions in energy, protein, and fat intake occurred in the low- and habitual-fiber groups only.Conclusions: Dietary advice to follow a high-fiber diet during pelvic radiotherapy resulted in reduced gastrointestinal toxicity both acutely and at 1 y compared with habitual-fiber intake. Restrictive, non-evidence-based advice to reduce fiber intake in this setting should be abandoned. This trial was registered at clinicaltrials.gov as NCT 01170299.

Original publication

DOI

10.3945/ajcn.116.150565

Type

Journal article

Journal

Am J Clin Nutr

Publication Date

09/2017

Volume

106

Pages

849 - 857

Keywords

Inflammatory Bowel Disease Questionnaire, cancer, fiber, gastrointestinal, nonstarch polysaccharide, pelvic, pelvic radiation disease, radiotherapy, short-chain fatty acid, toxicity, Adult, Aged, Aged, 80 and over, Diet, Dietary Fiber, Female, Gastrointestinal Tract, Humans, Male, Middle Aged, Pelvic Neoplasms, Radiation Injuries, Surveys and Questionnaires