Diet in the Treatment of Travelers’ Diarrhea

Abstract & Commentary

Synopsis: A randomized, controlled trial involving North American students visiting Mexico suggests that a restricted diet does not shorten the duration or severity of symptoms during travelers’ diarrhea.

Source: Huang DB, et al. The Role of Diet in the Treatment of Travelers’ Diarrhea: A Pilot Study. Clinical Infectious Diseases. 2004;39:468-471.

Huang and colleagues compared the effects of a restricted physiologic diet with an unrestricted diet on the duration and clinical symptomatology of acute travelers’ diarrhea in 105 college students attending summer sessions in Guadalajara, Mexico. The dietary study was done in conjunction with a study examining the effects of various antibiotics on the treatment of travelers’ diarrhea, with the primary end point being the duration of symptoms.

Travelers enrolled in this study were randomized either to adhere to a strictly controlled diet (48 patients) or to an unrestricted diet (57 patients). All were advised to drink fluids to match losses; however, those randomized to the controlled diet arm of the study were advised to consume solid starches, such as crackers and toast, and as their symptoms improved, to add bananas, rice, potato, baked chicken, and fish. They were also told not to consume milk products, fatty foods, coffee, alcohol, vegetables, or fruits, other than bananas, during the duration of their symptoms. Those randomized to the unrestricted diet arm of the study were told to eat whatever they wanted. Both groups kept diaries of their symptoms and of their daily intake. Similar numbers in each of the 2 groups received 1 of the 4 antibiotics under study. While the patients were not blinded as to which arm of the study they were in, those reviewing the diaries were. Three of the patients randomized to the unrestricted diet followed the restricted diet and 2 of the patients on the restricted diet followed an unrestricted diet. Huang et al performed both an intent-to-treat analysis, in which subjects were analyzed in the group to which they were originally assigned, and an efficacy analysis, in which subjects who did not conform to the assigned diet were reassigned to the diet group by which they actually practiced.

The study found no statistically significant difference in the clinical symptoms or the duration of diarrhea when the groups were analyzed by both the intent-to-treat and efficacy analyses. Thus, this study suggests that dietary interventions do not limit duration or severity of diarrhea in patients being treated with antibiotics for travelers’ diarrhea.

Comment by S. Kimara March, MD and Philip R. Fischer, MD, DTM&H

Travelers’ diarrhea afflicts between 20 and 50% of travelers to developing countries, and is one of the main topics covered in most pre-travel consultations. The pathogens causing travelers’ diarrhea are spread by fecal-oral contamination, with the majority of cases caused by bacterial enteric pathogens—enterotoxigenic Escherichia coli being the most common, followed by Shigella, Salmonella, and Campylobacter jejuni.1 While the implementation of advice offered during pre-travel consultation might prevent some cases of travelers’ diarrhea, the majority of travelers do not seek pre-travel advice, and even many of those who do still fall ill because they cannot control the hygiene of restaurants in which they take their meals.2 For this reason, most physicians not only discuss food and water precautions, but also discuss what is to be done in the event of illness.

Commonly offered pre-travel interventions for the presumptive management of travelers’ diarrhea include prescriptions for antibiotics, advice to remain hydrated, and to follow a bland diet during the duration of the illness.2-3 The study in Mexico specifically addressed the effect of dietary restrictions on the duration and degree of symptoms in those patients on antibiotics, ie, those patients most likely to have received pre-travel advice. The conclusion is clear that patients with travelers’ diarrhea, on antibiotics, do not benefit from following what has historically been known as the BRAT diet (Bananas, Rice, and other starchy foods, Applesauce, Toast) during illness.

It is children who most commonly suffer from diarrheal illnesses in the United States. Historically, a highly specific BRAT sort of diet was often recommended by pediatricians.4 Over the past 10 years however, research has shown that such a diet is not beneficial. Over the past several years, the Centers for Disease Control and Prevention, the American Academy of Pediatrics, and the World Health Organization have all concluded that diet should not be restricted in children with diarrheal illnesses.2, 5 Unfortunately, despite these uniform guidelines, it has been shown that the majority of physicians continue to recommend that patients restrict their dietary intake during illness.6

The thought behind the BRAT diet is that simple carbohydrates are easier for the intestines to process and absorb, and are less likely to contribute to osmotic load and further stimulation of intestinal motility.7 However, 70% of intestinal nutrients are derived directly from the gut and without these nutrients, the mucosa of the gut atrophies, thus impairing the mucosal barrier and limiting its ability to protect the host from harmful pathogens. Restricting dietary intake not only restricts nutrients required by the recovering mucosa, but also impairs gut immunity, promoting bacterial overgrowth.8 In addition, especially in children, severe malnutrition can occur after gastroenteritis if prolonged gut rest or clear fluids are prescribed; additional reasons why limiting dietary intake is not recommended.4

Other than oral rehydration therapy, there are promising agents which may be beneficial in the treatment of diarrhea. There is evidence that supplementation with zinc is beneficial to both malnourished children with acute diarrhea and to malnourished children who are at high risk of developing diarrhea.9 Lactobacillus rhamnosus strain GG has been investigated and has been shown to be effective in several placebo-controlled trials in the prevention and/or treatment of diarrheal illnesses.10 Whether zinc supplementation or Lactobacillus would help an otherwise healthy traveler with diarrhea, is not known.

Pending further research, pre-travel consultations should continue to include discussions of food and water hygiene for the prevention of travelers’ diarrhea. Presumptive treatment should include oral hydration and often, an antibiotic. There is no evidence that dietary restriction is of any value in the treatment of travelers’ diarrhea.

References

1. Von Sonnenburg, F, et al. Risk and Aetiology of Diarrhea at Various Tourist Destinations. Lancet. 2000;356:133.

2. DuPont HL, et al. Prevention and Treatment of Traveler’s Diarrhea. N Engl J Med. 1993;16:616-624.

3. World Health Organization. A Manual for the Treatment of Diarrhea. Geneva: World Health Organization, 1990.

4. Brown KH, et al. Effect of Continued Feeding on Clinical and Nutritional Outcomes of Acute Diarrhea in Children. J Pediatr. 1988;112:191-200.

5. American Academy of Pediatrics, Statement of Endorsement: Managing Acute Gastroenteritis Among Children: Oral Rehydration, Maintenance, and Nutritional Therapy. MMWR. 2003;52(RR-16):1-16; Pediatrics. 2004;114:507.

6. Guandalini S. Treatment of Acute Diarrhea in the New Millennium. Journal of Pediatric Gastroenterology and Nutrition. 2000;30:486-489.

7. Steffen R, et al. Diet in the Treatment of Diarrhea: From Tradition to Evidence. CID. 2004;39:472-73.

8. Duggan C, et al. "Feeding the Gut": The Scientific Basis for Continued Enteral Nutrition During Acute Diarrhea. J Pediatr. 1997;131:801-808.

9. Fuchs G. Possibilities for Zinc in the Treatment of Acute Diarrhea. Am J Clin Nutr. 1998;68:480S-483S.

10. Guandalini S, et al. Lactobacillus GG Administered in Oral Rehydration Solution to Children With Acute Diarrhea: A Multicenter European Trial. J Pediatr Gastroenterol Nutr. 2000;30:54-60.

Dr. March is a resident in the Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota.

Philip R. Fischer, MD, DTM&H, Professor of Pediatrics, Department of Pediatric & Adolescent Medicine, Mayo Clinic, Rochester, MN., is Associate Editor for Travel Medicine Advisor.