Diet determines gut bacteria

Continuing my interest/borderline obsession with all things gut bacterial, I offer this short post. It is a short post because this link to an entry in Science by Martin Enserink says just about everything I might want to say and probably better than I would say it. For those who want the slimmed down version.. for your consumption:

Enterotypes, that is categorised types of gut bacteria, seem to occur as a consequence of what form your diet takes according to this study by Gary Wu and colleagues*. So eat lots of meat and saturated fat and Bacteroides is the predominant species. If alcohol and polyunsaturated fats are among your primary dietary selections then Ruminococcus is your man/woman. Love your carbs? Then Prevotella predominates. Important also that whilst changes to fat and fibre content of your diet in the short term produce some detectable changes to gut bacteria, your enterotype seems to be a little more stable from meal to meal (at least in the 10 participants included in the trial over a period of 10 days).

There are so many more questions to be asked about this area of study. With my autism research hat on, I wonder what the bacterial consequences are when diets like a gluten- and casein-free diet are adopted, or when a specific carbohydrate diet (SCD) is followed over a course of months or years? Do the gut bacterial populations stay the same, or if not, could this conceivably tie into any behavioural effects noted from such dietary intervention the same way as happens when you 'shock and awe' gut bacteria with strong antimicrobials?

* Wu G. et al. Linking long-term dietary patterns with gut microbial enterotypes. Science. September 2011. DOI: 10.1126/science.1208344