Specific probiotic strains have been shown to reduce the symptoms of medically diagnosed irritable bowel syndrome. A randomised, double-blind placebo-controlled trial tested the efficacy of L.plantarum 299v in 40 people with IBS over four weeks. All patients treated with L.plantarum 299v reported significant improvement in stool frequency and complete resolution of their abdominal pain. An overall improvement in all IBS symptoms were noted in 95% of patients in the treatment group. Another study involving 204 adults with medically diagnosed IBS found significant symptom improvement within 2 to 4 weeks including improvement in abdominal bloating, pain and bowel movements.