What is the best diet for patients with gastroenteritis and watery diarrhea?

Best Foods for Gastroenteritis and Watery Diarrhea

For patients with acute gastroenteritis and watery diarrhea, resume an age-appropriate regular diet immediately after rehydration is complete, focusing on starches (rice, potatoes, noodles, crackers, bananas), cereals (rice, wheat, oat), yogurt, vegetables, and fresh fruits, while strictly avoiding foods high in simple sugars and high-fat foods. 1

Immediate Dietary Management

Infants and Breastfed Children

• Continue breastfeeding on demand throughout the entire diarrheal episode without interruption 1
• For bottle-fed infants, immediately reintroduce full-strength, lactose-free or lactose-reduced formulas after rehydration 1
• If lactose-free formulas are unavailable, full-strength lactose-containing formulas can be used under supervision, though lactose-free options are preferred 1

Older Children and Adults

Resume the regular diet during or immediately after rehydration is completed 1. The most effective foods include:

Recommended Foods (Prioritize These):

• Starches: Rice, potatoes, noodles, crackers, and bananas 1
• Cereals: Rice cereal, wheat cereal, and oat cereal 1
• Yogurt (contains beneficial probiotics) 1
• Fresh fruits and vegetables 1
• Soup 1

Foods to Strictly Avoid:

• High simple sugar foods: Soft drinks, undiluted apple juice, Jell-O, presweetened cereals (these exacerbate diarrhea through osmotic effects) 1
• High-fat foods: These delay gastric emptying and are poorly tolerated 1

The BRAT Diet: Limited Role

The traditional BRAT diet (bananas, rice, applesauce, toast) is reasonable as it includes starches and fruits, but prolonged use results in inadequate energy and protein content 1. Use it only as a short-term starting point, then rapidly expand to a full varied diet 1.

Evidence-Based Adjunct Foods

Green Banana (Strong Evidence)

• Cooked green banana significantly reduces diarrhea duration (median 4 days vs 5.5 days without it, P<0.001) 2
• Reduces hospitalization rates (9.2% vs 22.1%, P=0.03) and promotes faster recovery 2
• Protects against persistent diarrhea development (7.9% vs 19.5%, P=0.04) 2
• Dose: 250 g/L of cooked green banana daily has shown clinical benefit 3
• Works through dietary fiber effects on intestinal function 3

Probiotics

• Probiotics reduce symptom severity and duration in immunocompetent patients 1
• Most effective strains are Lactobacillus GG and Saccharomyces boulardii, which reduce diarrhea duration by approximately 1 day 4
• Effect is strain-dependent and dose-dependent 4

Critical Pitfalls to Avoid

When NOT to Use Standard Dietary Recommendations:

• If diarrhea is tarry or bloody, do NOT use anti-diarrheal medications and seek immediate medical evaluation 5
• Tarry diarrhea requires hospitalization and aggressive management, not home dietary treatment 5
• Blood in stool indicates complicated diarrhea requiring complete workup for infectious causes and GI bleeding 5

Lactose Considerations:

• While lactose malabsorption occurs in up to 88% of hospitalized children with rotavirus, continued milk-based feeding is clinically well tolerated and advantageous 1
• Only switch to lactose-free options if clinical lactose intolerance develops (worsening diarrhea upon lactose introduction) 1
• Laboratory findings alone (low stool pH or reducing substances) without clinical symptoms do NOT indicate lactose intolerance 1

Hydration Remains Primary

Oral rehydration solution (ORS) is the first-line therapy and takes priority over dietary interventions 1. Replace ongoing stool losses with 10 mL/kg ORS for each watery stool 1. Diet complements but does not replace fluid therapy 1.

Practical Algorithm

1. Rehydrate first with ORS until clinical dehydration corrects 1
2. Immediately resume age-appropriate diet focusing on starches, cereals, yogurt, fruits, vegetables 1
3. Consider adding cooked green banana (250 g/L daily) for faster recovery 2, 3
4. Add probiotics (Lactobacillus GG or Saccharomyces boulardii) to reduce duration 1, 4
5. Strictly avoid high-sugar foods, high-fat foods, and undiluted fruit juices 1
6. Continue breastfeeding without interruption if applicable 1
7. Replace ongoing losses with ORS (10 mL/kg per watery stool) 1