Abdominal pain is common in the general population and, in patients with irritable bowel syndrome, is attributed to visceral hypersensitivity. We found that oral administration of specific Lactobacillus strains induced the expression of mu-opioid and cannabinoid receptors in intestinal epithelial cells, and mediated analgesic functions in the gut-similar to the effects of morphine. These results suggest that the microbiology of the intestinal tract influences our visceral perception, and suggest new approaches for the treatment of abdominal pain and irritable bowel syndrome.

This pilot study investigated the immunomodulatory properties of seven probiotic strains. Eighty-three healthy volunteers aged 18-62 years consumed 2 x 10(10) CFU of bacteria or a placebo (maltodextrin) over 3 weeks (D0-D21). Subjects received an oral cholera vaccine at D7 and at D14; blood and saliva samples were collected at D0, D21 and D28. Serum samples were analyzed for specific IgA, IgG and IgM, and saliva samples were analyzed for specific IgA only, by ELISA. Statistical analyses were based on Wilcoxon's signed-rank test (intragroup analyses) and exact median t-test (intergroup analyses). Salivary analysis showed no difference in specific IgA concentrations between groups. Serum analysis indicated an effect of some of the tested strains on specific humoral responses. Between D0 and D21, IgG increased in two probiotic groups, for example, Bifidobacterium lactis Bl-04 and Lactobacillus acidophilus La-14, compared with controls (P=0.01). Trends toward significant changes in immunoglobulin serum concentrations compared with controls (P<0.1) were found for six out of the seven probiotic strains. In conclusion, some strains of probiotics demonstrated a faster immune response measured with serum immunoglobulin indicators, especially IgG, although overall vaccination was not influenced. Specific strains of probiotics may thus act as adjuvants to the humoral immune response following oral vaccination.

Commercial probiotic strains for food or supplement use can be altered in different ways for a variety of purposes. Production conditions for the strain or final product may be changed to address probiotic yield, functionality, or stability. Final food products may be modified to improve flavor and other sensory properties, provide new product formats, or respond to market opportunities. Such changes can alter the expression of physiological traits owing to the live nature of probiotics. In addition, genetic approaches may be used to improve strain attributes. This review explores whether genetic or phenotypic changes, by accident or design, might affect the efficacy or safety of commercial probiotics. We highlight key issues important to determining the need to re-confirm efficacy or safety after strain improvement, process optimization, or product formulation changes. Research pinpointing the mechanisms of action for probiotic function and the development of assays to measure them are greatly needed to better understand if such changes have a substantive impact on probiotic efficacy.

INTRODUCTION: Probiotics are live microorganisms that have a beneficial effect on the host. OBJECTIVE: Our aim was to investigate whether consumption of probiotics would be able to reduce symptoms of respiratory tract infections during the winter season. METHODS: Children aged 3 to 5 years were recruited and randomly assigned to 1 of 3 groups to receive placebo (n = 92), Lactobacillus acidophilus NCFM (NCFM) (n = 77), or a combination of L acidophilus NCFM and Bifidobacterium lactis Bi-07 (NCFM+Bi-07) (n = 79). Probiotics were consumed daily at a dose of 1010 colony-forming units for 6 months from November to April. The study was performed in Shanghai, China, and approved by the local authorities. RESULTS: The incidence of fever was reduced by 63% in the NCFM+Bi-07 group and by 48% in the NCFM group. Cough was reduced by 54% in the NCFM+Bi-07 group and by 42% in the NCFM group. Runny nose was reduced by 44% in the NCFM+Bi-07 group and by 9% in the NCFM group; the latter result was not significant. Antibiotic use was reduced by 80% in the NCFM+Bi-07 group and by 68% in the NCFM group. Children in the placebo group had, on average, 6.5 days with symptoms, those in the NCFM group had 4.5 days with symptoms, and those in the NCFM+Bi-07 group had 3.4 days with symptoms. CONCLUSIONS: Daily consumption of NCFM and Bi-07 and of NCFM alone significantly reduced the incidence and duration of respiratory tract infection symptoms in children. The combination of the 2 probiotics tended to perform better than the NCFM alone.