Two probiotics have been shown to assist in the management of IBS Align and VSL#3.
A single dose of VSL#3 contains 450 billion cells composed of three strains of Bifidobacterium (B. longum, B. infantis and B. breve); four strains of Lactobacillus (L. acidophilus, L. casei, L. bulgaricus and L. plantarum); and one strain of Streptococcus (S. salivarius subspecies thermophilus). A clinical trial on 25 IBS-D suffers showed that it provided some relief for bloating. It had no effect on other individual symptoms such as abdominal pain, gas and urgency.
The single probiotic bacteria species - Bifidobacterium infantis 35624 - found in Align was given to 362 IBS-D and IBS-C primary care patients. It was found that at the level of 100 million cells there was significant relief from many of the symptoms including pain, discomfort and bowel habits. This particular bacteria has been shown to have anti-inflammatory effects too. Align contains 1 billion of these cells.
I have been considering trying Align because it appears to be more effective.
References Whorwell, P. J., et. al 2006: Efficacy of an Encapsulated Probiotic Bifidobacterium infantis 35624 in Women with Irritable Bowel Syndrome. The American Journal of Gastroenterology, 101, 1581-1590.
Kim, H. J., wt. al., 2005: A randomized controlled trial of a probiotic combination VSL# 3 and placebo in irritable bowel syndrome with bloating. Neurogastroenterology & Motility, 17, 687-696.
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS