Abstract
(English)
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Effects of probiotic fermented product intake on immune function and faecal flora in the normal adult
In a randomized double blind placebo controlled study on healthy volunteers the immunomodulatory activities of Nestlé probiotic lactic acid bacteria (L. johnsonnii La1), and the transient persistence in the gut were confirmed. Transient 'colonisation' with probiotic bacteria did not modify the indigenous microflora in respect to Bacteroides and Enterobacteriaceae. Notably, the probiotic strains, but not S. thermophilus, showed a beneficial effect on host microflora by reducing the number of subjects positive for Clostridium perfrigens faecal colonisation. In addition, no inflammatory response was initiated during and after the nutritional intervention, as evidenced by the analysis of the acute phase proteins pre-albulmin, C-reactive protein (CRP) and a-1 acid glycoprotein and soluble (s)IL2- and (s)IL6 receptor in serum samples. Finally, the immuno-modulatory property of probiotic strains was demonstrated by an increase in the phagocytotic activity of peripheral blood monocytes and granulocytes.
High consumption of yoghurt was shown to modify cytokine levels, such as IFNg, in healthy volunteers. As an exploratory secondary objective, the frequency of IFNg secreting peripheral blood mononuclear cells (PBMC) in healthy volunteers before and after administration of probiotic products was determined by ELISPOT analysis
In total 15 volunteers/ group were analysed, revealing that there was a trend for an increased frequency of IFNg secreting cells after polyclonal restimulation. In conclusion, the number of circulating leukocytes, which will produce IFNg upon stimulation, is increased by short term consumption of probiotic yoghurts. However, these results are preliminary and need to be confirmed in more donors.
New markers of immuno-modulation were shown to be a useful tool to characterize probiotic activity of specific LAB strains. Immuno-stimulation of the host by probiotic bacteria has been demonstrated repeatedly. We showed in the present study that the immuno-modulatory capacity of Nestlé probiotic bacteria is not linked to an inflammatory type of immune response. As in precedent human studies, beneficial modifications of the host's microflora were detected after consumption of both probiotic strains. The transient colonisation of the human intestine had no negative effect on the number of commensals, such as Bacteroides and Enterobacteriaeceae. In contrast, an antagonising effect of on Clostridium perfrigens faecal colonisation was observed.
In conclusion, functional foods containing probiotic bacteria can preserve health by means of a better protection at mucosal surfaces. These products are important for the general population and could be of further use in specific age population like the elderly, or as supplementation in clinical nutrition.
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