What do systematic reviews say?

Dietary modifications (counselling or dietary change) vs no nutritional intervention

Dietary modification probably leads to lower diarrhoea at end of treatment compared with no nutritional intervention (moderate certainty).

• Nutritional interventions for reducing gastrointestinal toxicity in adults undergoing radical pelvic radiotherapy 2013 · Cochrane Headline outcomes only
  RR 0.66 [0.51, 0.87]
  4 studies · 413 participants
  Moderate