The recognition of the importance of a healthy gut flora is a comparably recent thing. It was first suggested in 1907 and the term probiotics was not coined until 1953. But more aspects of the intestinal flora and understanding its true relevance is only happening now. Recently there were some headlines about bowel content transplants, where the intestinal flora of one animal was transplanted to another and a significant portion of the first animal’s health or lack thereof seemed to be coming along with its bowel contents.
This may be one reason why it is not possible to “outrun” obesity (e.g. here: http://mashable.com/2015/04/23/obesity-exercise-uk-study/) – meaning eating an unhealthy diet (especially high in sugar and other carbs) and then staying healthy through enough exercise.
Even understanding what a healthy gut flora really is, is not as trivial as one might think. How is the ideal healthy gut flora defined? Of course you could just take healthy individuals and decide that since they are healthy, they must have a healthy gut flora. But that might be a non-sequitur. Recent research that I have cited here showed that indigenous tribes with what you might consider a more “traditional” or less “civilized” diet have a considerably different gut flora, containing – unsurprisingly – more soil based microorganisms than dairy based microorganisms. For that reason I am a firm believer in soil based probiotics, such as Royal Flora (see www.shopthewolfeclinic.com), rather than the dairy based ones.
Be all that as it may, here is some new research about the effect of probiotics on persons prone to depression. It appears that a healthy gut flora can prevent depression, which goes to show how far reaching the effects of intestinal health are.
http://www.nutraingredients.com/Research/Probiotics-could-prevent-depression-by-reducing-cognitive-reactivity/
Let me be cited here once more that I am all for probiotics, prebiotics and other supplementation, but never forget that a healthy diet is the basis of health. A person might still be healthy even if they can’t exercise or are sleep deprived, but an unhealthy diet will inevitably lead to bad health and can not be replaced by anything.