Gut microbes and health

I'd like to apologise to my Gutness Gracious Me blog. I've neglected you and your subscribers for quite a few months now and I'm sorry. I have no excuse so please accept my humble apology.

Friends again?

OK. There's been quite a bit of new research come out in the intervening months which I need to catch up on. For this entry I'm going to list a couple of interesting papers showing how, if it was ever needed, gut bacteria really are starting to be taken quite seriously in lots of science circles.

Nature is a good starting point (the journal Nature not nature in general). A whole supplement was recently dedicated to gut bacteria which can be viewed here. Unfortunately the papers aren't open-access but I might draw your attention to two of them in particular:

• Valentina Tremaroli & Fredrik Bäckhed* discuss the "functional interactions between the gut microbiota and host metabolism" and how gut bacteria might, just might have the ability to affect how we derive energy from our food. I suppose this crosses quite a few different issues such as 'is a calorie a calorie' and how overweight and obesity might not just be a simple 'energy in - energy out' relationship. Indeed the concept of gut bacteria potentially regulating metabolism and absorption of things like fatty acids as per this paper by Semova and colleagues** (discussed here) may very well also be relevant.
• The paper by Craig Maynard and colleagues*** highlights another important function of our gut bacteria with regards to immune function and how the communication between the two systems may have the ability to influence our health and ill-health. Other authors have similarly speculated on this process as per this study by Cucchiara and colleagues**** using pediatric inflammatory bowel disease as an example.

Next up is another Nature journal, Nature Neuroscience, which carried an interesting piece by Cryan & Dinan***** on the potential 'mind-altering' effects of gut bacteria and everyone's favourite term: the gut-brain axis. I've kinda done bacteria potentially influencing behaviour before on a sister blog entry (see here) so don't really want to rehash that again. Suffice to say that as well as being home to quite a lot of bacteria, our gut also houses quite a few neurotransmitters and their receptors more traditionally associated with brain, so why would we expect these not to potentially serve functions other than controlling gut motility and the like. Whether there is interaction between these neurotransmitters and gut bacteria.... well I'd speculate there might very well be.

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* Tremaroli V. & Bäckhed F. Functional interactions between the gut microbiota and host metabolism. Nature. 2012; 489: 242-249.

** Semova I. et al. Microbiota regulate intestinal absorption and metabolism of fatty acids in the zebrafish. Cell Host & Microbe. 2012; 12: 277-288.

*** Maynard CL. et al. Reciprocal interactions of the intestinal microbiota and immune system. Nature. 489: 231-241.

**** Cucchiara S. et al. Interactions between intestinal microbiota and innate immune system in pediatric inflammatory bowel disease. Journal of Clinical Gastroenterology. 2012; 46: S64-S66.

***** Cryan JF. & Dinan TG. Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nature Reviews: Neuroscience. September 2012.