Op-Ed: It may not be you feeling hungry! Do gut flora call the shots?

Posted Dec 19, 2012 by Paul Wallis
That desire to eat a few truckloads of food may actually be coming from your gut flora. Seems the little guys know how to tell you when they want to eat, according to a new study by the University of Rouen, France.
Variety of healthy food on the street market in Vila Madalena  Sao Paulo  Brazil.
Variety of healthy food on the street market in Vila Madalena, Sao Paulo, Brazil.
That real inner gut feeling actually relates to a whole range of issues and functions of gut flora, many of which are crucially important to health.
Science Daily explains how communicative gut flora can be:
"Bacteria both recognize and synthesize neuroendocrine hormones," Norris et al. write. "This has led to the hypothesis that microbes within the gut comprise a community that forms a microbial organ interfacing with the mammalian nervous system that innervates the gastrointestinal tract."
To be precise, the gut flora can interface with half a billion neurons. That’s quite a comm system, and the indications are that the gut flora know how to use it. They also generate a lot of very important chemistry in the body.
"The gut microbiota respond both to both the nutrients consumed by their hosts and to the state of their hosts as signaled by various hormones," write Norris et al. That communication presumably goes both ways: they also generate compounds that are used for signaling within the human system, "including neurotransmitters such as GABA, amino acids such as tyrosine and tryptophan -- which can be converted into the mood-determining molecules, dopamine and serotonin"
This is a direct link to a huge range of highly functional, extremely important chemistry in the human system. Dopamine and serotonin are the big mood-swingers, in particular. This is also where the symbiosis apparently kicks in, in no ambiguous way. Processing these compounds adequately requires healthy gut flora, and it’s no major leap of logic to see that feeling hungry also equates to shortages of what’s needed by the gut flora.
If a nutrient is lacking, you feel specifically hungry for that nutrient. Dieticians have long known that the common sense rationale of feeling better because you’re getting the food you actually need is pretty right. So do gut flora influence your choice of food? From the look of this study, the inference is that if they tell you what they want, it’s a good idea to go along with it.
It’s highly significant, though, that the interaction between crucial hormones like dopamine and serotonin is part of this study. It might even explain why people put so much thought into choosing their food. Food logic might be a bit shaky and self-indulgent at times, but when you eat something that makes you feel really good, you’re actually mapping your dietary needs to some extent.
It may also explain why the Paleo diet is getting such good results. Real food is beating fake food hands down. The gut flora aren’t equipped with the user manuals required to eat the processed slop. From the wide range of gastric disorders attributed to bogus food, they don’t like it much, either.
This is one case where going with your gut feelings is starting to make a lot more sense.