The aim of the present study is to assess the efficacy of two different probiotic products, lacto-fermented sauerkraut and the supplement Mutaflor, in the treatment of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a chronic gastrointestinal (GI) disorder that affects around 11% of the population globally. Several factors have been implicated in the pathogenesis of IBS, including psychological stress, gastrointestinal motility, and diet. More recently, it has become clear that the gastrointestinal microbiota may play a critical role in the pathophysiology of this functional GI condition.

Gut microbiome manipulation, for example through the use of probiotic and prebiotic supplements, has shown some promise in the treatment of IBS. However, the research in this area is still in its infancy, and it remains unclear what type of intervention that is the preferred choice in cases of IBS. Many, if not most, probiotic supplements on the market today contain bacteria that are incapable of colonizing the human gut, which may partly explain why the health effects associated with the use of probiotics tend to be temporary, rather than permanent.

Several studies have investigated how the use of probiotic supplements containing Bifidobacteria and Lactobacilli affect the clinical outcome of patients with IBS. However, to date, no studies have assessed whether fermented vegetables, a "natural" source of probiotic bacteria, are useful in the treatment of IBS. Moreover, little is known about how other types of probiotic bacteria, such as those belonging to the genus Escherichia, affect symptoms of IBS.

Inclusion Criteria:

Rome III criteria (Criteria fulfilled for the last 6 months with symptom onset at least 3 months prior to diagnosis):

Recurrent abdominal pain or discomfort at least 3 days/month in the last 3 months associated with two or more of the following:

1. Improvement with defecation
2. Onset associated with a change in frequency of stool
3. Onset associated with a change in form (appearance) of stool

Exclusion Criteria:

• Psychiatric disorder
• Metabolic disease
• Chronic infection
• Organic gastrointestinal disorder
• Pregnancy
• Breastfeeding