Probiotics
http://en.wikipedia.org/wiki/Probiotic
Advances in Experimental Medicine and Biology, vol.635 - GI Microbiota and Regulation of the Immune System (Springer, 2008).pdf
Probiotic trials:
http://www.sciencedaily.com/releases/2010/05/100519081329.htm
Oral Bacteria May Offer Probiotic Potential Against Upper Respiratory Infections
http://www.sciencedaily.com/releases/2010/06/100618142511.htm
