The study aims to investigate the effect of probiotics on IBS-patients symptoms compared to placebo, when given for 6 months.

By draw the investigators give IBS patients, in the age of 18-50 years, capsules with either probiotics or placebo. The patients are to take 2x2 capsules / day for 6 months. The patients are followed for 1 year. They are seen after 3, 6 and 12 months, and are followed by means of monthly letters.

The capsules contain 3 different probiotic strains - Lactobacillus paracasei ssp paracasei F19, Lactobacillus acidophilus La5 and Bifidobacterium Bb12. The dose is 2 x 109 - 10 x 109 CFU/capsule.

The hypothesis is, that there is a clinical difference between the group receiving probiotics and the group receiving placebo.

Background: In management of IBS, no treatments have showed great efficacy. IBS is a non-fatal disease, so safety is a high priority in the choice of treatment. Probiotics is a dietary supplement and have no adverse effects. In some studies it has shown beneficial effect on some of the IBS patients symptoms, but some of the results are questionable. The studies have to be of longer duration, with more patients and the probiotics have to be capsules instead of milk based drinks.

Inclusion Criteria:

• Fulfill ROME III criteria
• age 18-50 years
• signed informed content

Exclusion Criteria:

• Danger signals (fever, anaemia, weightloss, blod in stools, predisposition for CRC or IBD)
• abnormal physical examination
• comorbidity
• abuse
• lacking ability to talk and understand danish
• pregnancy
• For patients > 40 years. Changed bowel habits, with duration > 3 weeks, but < 1 year