Dead or alive: Benefits of probiotics need live organisms
Animal and cell experiments showed that the immune system modifying effects of the strain Lactobacillus salivarius ssp. salivarius CECT5713 was dependent on the bacteria being alive, according to findings published in the European Journal of Nutrition.
An area of ongoing debate is whether the dead forms of beneficial bacterial strains have a role to play in conferring benefits to the host in formulations – even if they did not meet the World Health Organization definition of probiotics as being “live microorganisms”.
According the FAO/WHO, probiotics are defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host".
“Although some studies have proposed that the viability of probiotics is not essential to exert its anti-inflammatory effect, their effects may be due to their immunostimulatory DNA,” wrote researchers from the University of Granada in Spain and the University of London in England.
“However, this is not a constant feature in all probiotics since different in vitro studies have reported that viable probiotic is required to exert anti-inflammatory effect.”
According to their data, live or ‘viable’ L. salivarius ssp. Salivarius CECT5713 (Biosearch Life, Spain) is “essential for displaying the beneficial effects”.
Study details
The researchers compared live and dead (heat treated) bacteria in a rat model of colitis and concluded that “the viability of the probiotic was required for its anti-inflammatory activity”.
This was followed by a test with Caco-2 cells, a line of cells similar to those found in the lining of the intestine. Results from this assay showed that the when the cells were exposed to either interleukin-1B (IL-1B), a compound that plays a role in the inflammatory response, or E. coli resulted in increased levels of interleukin-8, another inflammatory compound. The probiotic, however, significantly inhibited the production of IL-8, said the researchers.
Finally, the probiotic was tested in mice with an altered systemic immune response, and was found to inhibit the production of tumor necrosis factor-alpha (TNF-alpha), a well-established marker of inflammation.
“Most of the studies performed with probiotics have been focused on their beneficial effects on the gastrointestinal tract,” wrote the researchers.
“However, it is more and more evident that although these microorganisms may exert their beneficial effects due to the well-known ability to modulate intestinal microbiota and affect the intestine immune response, these effects are not restricted to the gastrointestinal tract.”
Source: European Journal of Nutrition
Published online ahead of print, doi: 10.1007/s00394-011-0221-4
“The immunomodulatory properties of viable Lactobacillus salivarius ssp. salivarius CECT5713 are not restricted to the large intestine”
Authors: B. Arribas, N. Garrido-Mesa, L. Peran, D. Camuesco, M. Comalada, et al.
