Do probiotics help an upset stomach?

Kerry Beeson BSc (Nut. Med.) Nutritional Therapist

Trillions of bacteria live inside us; in fact, the bacteria in our gut is essential to help us digest our food. However, eating foods our bodies aren't used to, or consuming something that's 'gone off' can often result in a stomach upset. Having an upset stomach is uncomfortable at the best of times: it's exhausting, debilitating, not to mention painful and can completely disrupt everyday life. This short article should help to shed some light on the subject and hopefully help a few people in the process.

Upset Stomach - IBS & diarrhoea

People often ask whether probiotics can help an upset stomach and, in short, the answer is yes. Specific strains of good bacteria have been known to help alleviate the symptoms of illnesses including IBS (see the Probiotics Learning Lab for more info) and diarrhoea and reduce the symptom duration by up to 24 hours. One particular strain, clinically trialled1 to reduce the effects of stomach upsets, is Saccharomyces boulardii, unique from other bacterial strains such as L. acidophilus because it is actually a probiotic yeast, originally found in lychee fruit. This strain is known for its transient (see the Probiotics Learning Lab for more glossary terms) qualities, meaning that it doesn't colonise in the intestines. Interestingly, it is thought to have a sticky outer membrane which it may use to adhere itself to harmful bacteria including E. coli and Salmonella. This process is thought to help remove the bad bacteria from the system - it is the only probiotic that does this.

The NHS2 has even reported on this topic on their website; examining a review which looked at a number of clinical studies on probiotics and stomach upsets - and concluding that they "reduced the duration of diarrhoea by about 25 hours compared with no treatment".

tummy ache

Saccharomyces boulardii is particularly well-documented for diarrhoea

In layman's terms, S. boulardii is thought to attach itself to the bad bacteria and slowly remove it from your system. This may help to reduce IBS and diarrhoea symptoms by up to 24 hours, allowing you to get back on your feet quicker. For more information on Saccharomyces boulardii.

Travellers' Diarrhoea

Whether you're going away to a familiar destination, returning home to see family or backpacking to distant lands to explore uncharted territory, holidays are invariably a memorable experience. However, sometimes these new experiences can also produce some nasty and uncomfortable stomach-related side effects.

Normally, our gut is exposed to a certain type of bacteria in everyday life and our immune system is accustomed to this. However, when we visit different countries, our bodies become exposed to very different types of bacteria that we may not have encountered previously, usually by consuming the food and drinking water. Consequently, our body goes into a 'defence mode' which causes stomach upsets, sickness, diarrhoea, and general discomfort. Trying the local cuisine in countries such as Thailand, India, Egypt or Cambodia which could include eating frog, snake, silk worms or even scorpion (certainly not for the faint-hearted) may also lead to diarrhoea or sickness, often referred to as "Travellers' Diarrhoea". Even drinking the water in some exotic counties can cause illness.


Saccharomyces boulardii also happens to be a probiotic that helps ease the effects of “traveller’s diarrhoea”, clinically researched3 to support gut health in those that travel abroad to exotic locations. S.boulardii, as mentioned above, works differently from other probiotics specifically because of its unique transient qualities. This means that it can pass through the system without binding to the gut wall. It works by adhering itself to harmful bacteria and gently removing those unwelcome pathogens from the system.

When travelling abroad, it’s also considered a good idea to take other types of probiotics alongside Saccharomyces boulardii in an effort to battle bad bacteria in two ways. Live cultures, like L. acidophilus and L. rhamnosus are thought to possess qualities that allows the natural bacteria to line the interior of the gut wall, creating a barrier and fortifying the gut's natural defences. These properties can be a particular aid against so-called “Delhi Belly”.

Whether you're experiencing stomach discomfort at home, or in a hostel in Mumbai, you are now aware that certain strains of probiotics may help to ease associated symptoms.

See more related articles below:
Classification of Saccharomyces boulardii
Exploring probiotics, friendly bacteria and PCOS


1. Hochter, W. et al (1990) 'Saccharomyces boulardii in acute adult diarrhea. Efficacy and tolerance of treatment.' Munchener Medizinische Wochenschrift; Vol. 132 (12) pp. 188-192


3. Kollaritsch, H. et al. (1993) 'Prevention of traveler's diarrhea with Saccharomyces boulardii. Results of a placebo controlled double-blind study'. Fortschr Med, 111(9): 152-6