Probiotics & Traveler's Diarrhea

A recent meta-analysis on the use of probiotics to treat traveler's diarrhea was published in March of 2007, and here is a summary of that review. I assume most of us have experienced this problem and I will elucidate why it happens and the success probiotics have had in the literature at preventing it. All facts unless otherwise noted are included or cited in the meta-analysis. I wrote this objectively and can provide full text on request.

Traveler's diarrhea (TD) is a frequent problem with 12 million reported cases every year. Depending on the destination, the risk of TD can be high or low. From traveler reports to places such as northern Africa, Latin America, the Middle East, and Southeast Asia, the likelihood of intestinal disturbance is greater than 50%. North America, northern Europe, Australia, New Zealand, and the United Kingdom are less frequent with only 5-10% of travelers reporting problems. This paper states that "TD is acquired by ingestion of fecally contaminated food, water or other liquids." Raw or undercooked meats, seafood, and unpeeled raw fruits and vegetables, tap water, ice, non-pasteurized milk, and other dairy products are among the main causes. The riskiest foods come from street vendors, farmers markets, and small restaurants. I personally believe the local farmer market and business should be promoted, as long as foods are handled properly. The interaction with these types of markets in a foreign community is a rewarding part of a traveling experience.

When a contaminated food or drink is consumed, it does not cause an immediate reaction. The incubation period generally takes 2-3 days and then the symptom of diarrhea results. Diarrhea is defined in the literature as 3 or more loose stools per day for at least 2 days or 5 or more within 48 hours. TD generally persists for 2-6 days if untreated, however up to 15% of cases are extensive- 1 week to 1 month, or even to 1 year. Accompanying side effects include: abdominal cramps, nausea, and less frequently vomiting and fever. 35% of 784 tourists in one study reported changing their travel plans due to TD, resulting in an economic loss to the travelers and the country. Military personnel would benefit from probiotic consumption, as TD is the "common prevalent non-combat medical condition" in troops on short missions at 29%.

80-85% of TD cases are caused by bacterial pathogens, and a much smaller percentage by viruses and parasites. Some causes cannot be determined. Bismuth subsalicylate (Pepto-Bismol active) and prophylactic antibiotics are often used to combat TD. However, frequent doses are required and it is not recommended to be used more than 3 weeks. The use of antibiotics is a bad idea in my opinion, since the gut bacteria are essential in immunity, which is especially needed in a new environment. Probiotics are the perfect substitute, and are able to ward off pathogenic bacteria and viruses by blocking their binding to the mucous membrane in the intestine. This not only prevents infection but also enhances the immune response and helps to re-establish normal microflora from the new environment.

The objective of the analysis was to "assess the efficacy and safety of probiotics for the prevention of TD." Inclusion criteria were: "randomized, controlled, blinded efficacy trials in humans published in peer-reviewed journals." The authors dug through 940 probiotic citations to find 12 treatments in the 7 best studies on probiotics in travelers totaling 4,709 subjects. When all data was pooled, the estimated risk prevention by probiotics was 85%. From the data, there seems to be a weak dose dependent pattern, as well as different results between strains and cities. This may be from exposure to different pathogens and an individual response to various strains. Surprisingly is the lack of efficacy of the L. acidophilus strain in a few of the treatments, commonly found in various dairy products in the United States. Some of the treatments included mixtures of different strains to attempt to more closely mimic the natural colon environment with multiple strains, and were not any more effective than the single strains. One of the studies reported abdominal cramping with 2% of the subjects who were consuming L. rhamnosus GG, a common strain used in supplements. No other adverse effects were reported.

Since the studies in this analysis were very broad, there may be conflicting results. Populations, doses, treatment duration, destination, potency, compliance, behaviors, and age are listed as differences. This means more research is necessary to find which strains work best for each situation. However, this gives us a good overview of the efficacy of a general probiotic product- although there are some strains that are more effective than others, when pooled together they represent an easy and effective prevention of TD. It should be noted that probiotics in doses less than 10 billion organisms are generally considered "sub-therapeutic" in the literature, however there was no significant risk change dependent on dose for TD.

Normal intestinal microflora takes around 6-8 weeks to become re-established after significant changes. Delayed TD is a reality, but unfortunately the studies did not report delayed TD. It is my opinion based on this data that probiotics should be started minimally 1 week prior to departure to destination, all throughout the stay, and at least 2 months after return.

Most probiotic products require refrigeration, which result in a minimal amount of organisms actually reaching the consumer before even opening the bottle, and without the ability to control climate in many parts of travel, can be ineffective. One study reports no effect on TD for strains which were intentionally killed.

We of course recommend our own product Güt Health which has been studied extensively and is effective at treating diarrhea in general, and is also shelf stable.

McFarland LV. Meta-analysis of probiotics for the prevention of traveler. Travel Medicine and Infectious Disease 2007;5(2):97-105.

Let us know if you are traveling and would like to test the effectiveness of Güt Health on TD.