Friday 18 October 2019

We all got guts

Wexford Science Café WSC met, as ever, on the 3rd Tuesday [15th] of October 2019 in the Sky&Ground. It was me, again [*], talking about the gut and its darkling denizens. This has been of spectator's interest to me for at least a decade and is more recently surfacing into public discourse both scientific and popular-press. Needless to say, a lot of unsubstantiated nonsense is uttered in the latter medium. The field is at the stage now where a lot of data is accumulating that changes in the gut microbiota are associated with irritable bowel syndrome IBS; inflammatory bowel disease [worse!] IBD: Crohn's Disease CD, ulcerative colitis UC; peptic ulcer [Helicobacter prev]; obesity; diabetes. No surprises there; although it is not obvious what is the cause and what the effect of these co-occurences. What might be more surprising are the psychobiotic associations between the gut flora and . . . anxiety, autism, chronic fatigue, dementia, depression, Parkinson's. And note that your gut flora goes on a journey from cradle to dotage with different classes of microbes rising and falling in a reasonably predictable manner as we age.

Sources: nobody expects you, dear reader, to get down and dirty with the scientific literature. Each paper will normally present only one study indicating that bacterial strain X is associated with condition Y in either mice or humans, occasionally both. If you take the materials and methods on trust [and you shouldn't!], you can get the key factlet from the PubMed abstract. Or you can read Giulia Enders book: Gut: The Inside Story of Our Body's Most Underrated Organ; [originally Darm mit Charme. Alles über ein unterschätztes Organ] which I reviewed a tuthree weeks ago. I was all set to present an ExecSummary of that book when one of the WexSciCaf lurkers pointed me at The Psychobiotic Revolution by Anderson, Cryan and Dinan. Scott Anderson is a US-based science journalist, while John Cryan and Ted Dinan are academics from UCC in the Independent Republic of Cork.

In the airy arm-wavy world of popular science books you have to polish your crap-detector before you invest time and money in 'facts' therein presented. Here, I'll share some of the interesting intel which I gleaned from my reading.

The money is in probiotics but you and I don't want to spend our hard-earned dollars on products of dubious efficacy and doubtful quality control. Dinan & Cryan cite one study where the contents of 13 probiotic supplements were compared to what it said on the tin. Only 4/13 had a table of contents than actually matched the contents. Probiotics are food supplements and have a far lower administrative and licencing bar to leap than drugs which are classified as medicine. But the thrify should follow the prebiotics route: these are the dietary changes that can encourage the growth of good bacteria: try ginger, garlic, carrots, apples for starters. Actually, keep it simple and follow Michael Pollan [multiprev]: Eat food; not too much; mostly plants. Un-food is anything that comes in a packet with more than 6 indredients.

There has been a bit of interest recently in the few cases of auto-brewery syndrome. This occurs when a colony of bakers' yeast Saccharomyces cerevisiae, against the odds and its normal environment, sets up shop in some person's intestine. There it scarfs up any passing sugar and anaerobically converts it to ethanol and carbon dioxide. The CO2 causes a certain increase in fartiness but the alcohol crosses the intestinal epithelium and starts to intoxicate. I don't think you'd have a leg to stand on [you'd be legless, arf arf] in court if you got arrested for driving under the influence.

Now before I forget, I'll note some of the major players in the gut flora: some good and some bad; all just tryimng to make a living. There may be 1,000 different species of microbe donw in the dark, but 99% of them fit into 4 different Phyla [major groups of bacteria]
  • Actinobacteria
    • Bifidobacterium longum, B. breve; B. dentium [richer in infant guts]
    • Proprionobacterium shermanii [bubbles in Emmenthal]
  • Firmicutes
    • Clostridium difficile, C. botulinum [botox]
    • Bacillus cereus [re-heated rice poisoning]
    • Lactobacillus spp. LABs good guys
  • Bacteroidetes
    • Bacteroides thetaiotaomicron [prev]; B. fragilis; B. plebeus [freq in Japan]
    • Prevotella
  • Proteobacteria
    • alpha: Rickettsia prowazekii; Brucella abortus [prev Alice Evans]
    • beta: Neisseria gonorrhoeae, [the clap] N. meningitidis [meningitis]
    • gamma: Escherichia coli and other enterics incl Salmonella; Pseudomonas aerogenosa
    • epsilon: Campylobacter jejuni [food poisoning] Helicobacter pylori [ulcers]
[*] Footnote: Wexford Science Café is still trundling along - but seemingly only if  I continue to push and heave t'bugger up hill. It just doesn't seem to be gathering momentum although further adherents occasionally appear. As with a lot of such voluntary things, 90% of the work is done by 10% of the people. As a max of ten people turn up on a good day, the 10% is Me. When the call for next month's speaker is issued, everyone looks at their feet. And nobody seems willing to take on the minute adminstrative burden of calling the faithful to prayer once a month [Over the Summer, I e-asked this question direct of several of our most frequent attenders, only some of whom bothered to reply and all of whom were too busy]

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