Probiotics: the human biome

I limit my advice to evidence informed practice. Until recently there was little evidence for the vast majority of supplementation for all except those proven to be clinically deficient in a vitamin or a mineral. Now there is some moderate evidence for some supplements, among the strongest evidence is that for probiotics and prebiotics.

Probiotics are spores and live culture of beneficial bacteria and some yeasts. Typically these are bifidus and acidophilus bacteria that have a moderating effect on the colon enhancing digestion. These bacteria are sometimes called lactobacillus as they are commonly associated with fermented dairy products such as yoghurt. They have shown preliminary good results for antibiotic associated diarrhoea and some effectiveness with irritable bowel syndrome. There is a little evidence that it may have a beneficial effect on allergies and atopy. There also seems to be an effect on Helicobacter pylori in the stomach. H. pylori has been associated with ulcerative gastritis so controlling it is useful.

I discovered in my reading a new probiotic product for the pharynx and upper respiratory tract called BLIS K12. The bacteria in this probiotic is a strain of streptococcus salivarius. BLIS stands for Bacteriocin-Like Inhibitory Substances. K12 is a particularly aggressive  and territorial bacteria that produces many BLIS. It was isolated by Prof John Tagg at the University of Otago in an epidemiological study to determine whether there was a bacterial culprit for repeated ear and throat infection in school aged children. It was paradoxically found that the absence of this naturally occurring strain of bacteria left the child more vulnerable to chronic bacterial infection. Children dosed with this strain had fewer infections.

I offer BLIS K12 to my patients if they have repeated upper respiratory tract infections.

There are many other plausible biotic agents that may one day be used routinely to treat disease in medicine. One I am particularly interested in is helminths. Helminthic therapy is an attempt to moderate auto-immunological response by introducing microscopic intestinal worms. These worms have been effectively eradicated due to modern hygiene. The hypothesis goes that when the immune system isn’t exercised in the controlling of helminthic population in the gut, it turns on other targets in the body  and creates hypersensitivity diseases such as asthma.

If you think that stretches your imagination try fecal microbiota transplantation. This therapy is used against clostridium difficile infection which is a big killer of the hospitalised. C. difficile is rightly named as it is difficult to eradicate with antibiotics. It seems to respond strongly when fecal matter from a person that is genetically and/or habitually close to the infected is transplanted transrectally into the sufferer’s colon. The transplanted microflora seem to colonise and suppress the C. difficile infection.


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