Which dietary modifications should I recommend to a patient with chronic diarrhoea while awaiting further investigation?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 16 August 2025Updated: 16 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

While awaiting further investigation for chronic diarrhoea, you can recommend the following dietary modifications to the patient:



  • General Eating Habits:

    • Encourage the patient to eat regular meals and take time to eat, avoiding missing meals or leaving long gaps between eating ,.

    • Advise drinking at least 8 cups of fluid per day, especially water or other non-caffeinated drinks like herbal teas ,. Ensure adequate fluid intake, particularly if there is a risk of dehydration ,,.



  • Specific Food and Drink Modifications:

    • Advise reducing the intake of insoluble fibre, such as wholemeal or high-fibre flour and breads, cereals high in bran, and whole grains like brown rice ,.

    • Suggest limiting fresh fruit to 3 portions per day (approximately 80g per portion) .

    • Recommend reducing intake of 'resistant starch', which is often found in processed or re-cooked foods .

    • Advise reducing or limiting foods and drinks that may exacerbate symptoms, including caffeine, alcohol, and carbonated drinks ,. Specifically, restrict tea and coffee to 3 cups per day .

    • Consider if symptoms are worsened by dairy products, which may suggest lactose intolerance .

    • Be aware that diarrhoea can be due to consumption of food additives, such as sorbitol .



  • Important Considerations:

    • If attempting to identify potentially contributory factors, advise the patient to modify one food at a time .

    • Encourage the use of a food and fluid diary to help establish a baseline and track symptoms .

    • Emphasise that overall nutrient intake should remain balanced .

    • If general lifestyle and dietary advice does not help, referral to a dietitian for further dietary management, such as a low-FODMAP diet or single food avoidance, should be considered under specialist supervision to ensure a balanced and nutritious diet .



Educational content only. Always verify information and use clinical judgement.