h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Actually no, the probiotic yogurt thing was recently demonstrated to be utterly false.

Yes we have a close symbiotic relationship with our symbiotic partners. Yes they can affect the things you say - it seems - we have a LOT to learn about this. Look at how we discussed the levels of gut microbes above - I'm a practicing biological chemistry and hadn't seen that latest estimate on gut bacterial numbers. Published in 2016, so already three years out of date - perhaps someone soon will get an even better idea.
So we don't *really* know for sure, even how many there are, let alone *what* they all are.
The latest stuff I saw, was about a year or so ago -and it was secondary source off the news and internet - was that a balanced guy biome is a very individual thing - what works for one person may well be utterly different to that of another. And their main conclusion was really that since probiotic yogurts and drink are all the same, then they are *very* unlikely to be of any use to the general population - despite the claims in the adverts.
(I used to be a big proponent of these - ho hum - but one should change one's mind if more accurate and well-researched data arise that debunks what was once thought).

it's a very active research area, complicated by the fact that these things grow in inaccessible areas of our bodies (and those of other animals) and 'invasive' intervention' in having a look may well change the culture environment and change things. My colleagues are actually trying to set up where I work to contain a research institute in this area... I hope so because it's fascinating. We know so little about it currently and we really wish to learn more of what's in gut biomes alongside how they communicate with each other and us.

Yeah, I tried several probiotics with various claims of efficacy, a few years ago and noticed no significant effects. (No weight loss, no significant mood changes, no relief to my lower GI issues.)

These issues may very well be related to my personal gut biome, but taking a pill orally doesn't seem to effect it. I suspect whatever is in those pills, if it's even still living when I swallow the pill, is unlikely to make it through the acid bath of my stomach.


A thought occurred to me when I was trying these and thinking about our biomes. Can humans actually survive for very long times (generations, not years) off of Earth. We evolved in a very particular environment with very specific symbioses with the microbes in this environment. We know that our overuse of antibiotics has a huge detrimental effect on many of these necessary microbes. But if we put ourselves in an environment where all these myriad microbes are nonexistent, we could easily wipe out those we carried along with us. And then, well, we're screwed!

I suspect bacteria are better at surviving stomach acid that we like to think - it's rather easy after all, to get salmonella, campylobacter, lysteria and other bacterial infections through eating contaminated food. And you wash your hands after defaecating for a reason.
But an awful lot will die in the digestive system too of course. Enough often survive to start or repopulate a colony.

Interesting last point. Very interesting. Believe it or not, NASA and other organisations do actually use that principle seen in Star Trek of not intervening in a foreign planet. So all space-vehicles are thoroughly sterilised before use (though clearly some other space agencies are not quite so Prime-Directive conscious). I suspect it's an excellent point - not lost on those looking into going to Mars, but I've not personally seen (or looked) for any thoughts on this from them.

If you're eating yogurt because you like the taste, and there are few significant effects one way or the other, I see no harm in it.

It was once thought that the appendix was a reservoir of vital gut bacteria, a reserve that could be used after a die-off of the bacteria in the rest of the gut. That theory has probably been altered greatly since it came out, but I can't help being more out of date than the scientists in this thread.

Absolutely, eat yogurt yum. What's not very one though is misleading people that it's some sort of 'neutraceutical' as the modern terminology calls such things. Medical benefits should be demonstrated by double blind clinical trials as with drugs if your going to make such claims Imnsho.

Your latter theory has some merit perhaps - dunno. Certainly It is an evolutionary remnant of other digestive compartments in other creatures - see the 4 'stomach' in ruminants.

An phenomenon that might be of interest I encountered when one of my colleagues gave a lecture not so long ago. He was looking at how gall-stones - which are made of toxic oxalic acid (famously made in rhubarb leaves) - or a calcium salt of it at least - are made in the body.

It turns out calcium oxalate is transported from a specific species of anaerobic bacterium in the duodenum (lower intestine) which make it by an artefact of their unique metabolism (where they have evolved to lose a more important biosynthetic pathway that means they die if they are not *exactly* where they exist in the duodenum). Only people with this bacterium get gall-stones I think I recall correctly.

Turns out, only about 1 inch of the full length of the duodenum is anaerobic (i.e. there is no oxygen) - so they cannot survive outside of this area as oxygen will kill them.

So.... how did it get there? How do new people acquire it? Also sadly, how on earth do you administer a treatment to just that area of the gut?

It's a very very weird and poorly undestood area of biology/biochemistry/microbiology etc.

(it might have been kidney stones, not sure)

If there are kidney stones in the gallbladder, someone has a big problem.





(Seriously, people who are prone to kidney stones should refrain from drinking diet soft drinks)

Definitely kidney stones. Just checked.

Ditching the diet soft drinks should help there.