Functional gut problems, such as those classified by the Rome criteria as IBS are a significant health problem for many people. The use of probiotics as a single or multiple intervention offers a potential route to resolution, but the data is as yet inconsistent and in need of further clarification. This is the opinion of a group from Thames Valley University in a recently published review.
ABSTRACT: Irritable Bowel Syndrome (IBS) is a substantial burden on healthcare systems. There are a plethora of probiotic products on the market that target gastrointestinal problems. This review aims to guide the healthcare practitioner to make an informed judgment when prescribing probiotic products for alleviating the symptoms of IBS, as conventional medication has been found to have a few adverse effects. Six recent systematic reviews and 27 clinical trials were analysed. The microbial content of twelve commercial products was examined. All the extracted evidence was summarised and critically reviewed. The quality of the research was found to be limited and often contradictory. A need for studies of longer duration and of larger sample size was identified. Dosages in clinical trials varied greatly as did the use of multi or single strain products. Two parameters were selected (global improvement and abdominal pain) and probiotic species were scored according to their performance in clinical studies. Lactobaccilus rhamnosus scored the highest for improvement of global symptoms and Lactobaccilus acidophiphilus scored the highest for improvement of abdominal pain. Probiotics have few adverse effects, and although they may not supply the cure for all the symptoms of IBS, they could provide a way to self-manage the condition. The increase in research dedicated to understanding and proving the efficacy of probiotics should mean that before long current inconsistencies in research methods are removed.
In nutritional therapy practice, there are many times when a decision as to which species or ideally which strain may offer the best outcome. This paper does an admirable job in trying to assist that clinical decision based on published data. It is reflective of the somewhat variable trials, endpoints and size that the outcomes favour the three species and strains I have written about for some years. Lactobacillus GG, Saccharomyces Boulardii (Lyo) and Bifidobacteria bifidus. One other strain, produced by Procter and Gamble B.infantis 35624 is also showing early promise.
The top four species for global improvement obtained the following scores:
- L. rhamnosus (4)
- B. bifidum (3)
- B. animalis (2)
- Propionibacterium freudenreichii (2)
The top four species for the improvement of abdominal pain obtained the following scores:
- L. acidophilus (8)
- B. bifidum (3)
- L. plantarum(3)
- L. rhamnosus (3)
Single or multiple strain therapy?
One paper published in 2007 found insufficient evidence to conclude whether multi-strain preparations are more effective than preparations containing a single strain, and that a wide variety of probiotic/symbiotic strains and combination products may not be effective for all the unique combinations of gut flora in each individual. 
The combined use of single or multi strain probiotics in conjunction with food choice modification and lifestyle choices still represents a very effective approach to clinical management of functional gastrointestinal issues.
I recommend that patients are encouraged to monitor their outcomes by using a well-established online scoring system. http://www.ibsjennifer.com/ This permits a review to take place based on historical and accurate feedback, and permits a better application of nutritional therapy as a mechanism for managing functional bowel disorders.
 Botschinsky B, Botschinsky D and Tsiami A. A review of the evidence available for the use and effectiveness of probiotic drinks and supplements for the treatment of irritable bowel syndrome. International Journal of probiotics and prebiotics. Vol 6, No1, pp. 21-38, 2011 View Abstract
 Eddins C, Gray M. Do probiotic or synbiotic preparations alleviate symptoms associated with constipation or irritable bowel syndrome? J Wound Ostomy Continence Nurs. 2007 Nov-Dec;34(6):615-24. Review.