It’s a typical scenario: You tell yourself you’ll have a salad for lunch. Suddenly, 1pm rolls around, and you find yourself feasting on fried chicken and washing it down with an extra-thick milkshake. Sound familiar?

According to a new study (PDF) by researchers at UC San Francisco, Arizona State University, and the University of New Mexico, it may actually be bacteria in our gut controlling our moods and giving us cravings for foods that they want to eat—as opposed to what we know we should be eating. 

Dr. Carlo Maley, one of the co-authors of the paper, spoke to the UCSF blog about those bacteria:

“Bacteria within the gut are manipulative. There is a diversity of interests represented in the microbiome, some aligned with our own dietary goals, and others not.”

However, Maley also advises that we do have the power to influence those bacteria by making conscious decisions about what we want to eat. The bacterial population is also called the microbiome, and according to Maley, dietary changes alter the microbiome within 24 hours. He explains, “Our diets have a huge impact on microbial populations in the gut. It’s a whole ecosystem, and it’s evolving on the time scale of minutes.”

Dr. Athena Atkipis, another co-author on the paper, elaborated on what those sneaky gut bacteria want, and what they’re willing to do to get it:

“Microbes have the capacity to manipulate behavior and mood through altering the neural signals in the vagus nerve, changing taste receptors, producing toxins to make us feel bad, and releasing chemical rewards to make us feel good.”


Photo: The Technodrome

What the hell is the vagus nerve? It’s a communications superhighway from your intestinal tract directly to your brain, which contains over 100 million nerve cells. Now that’s high-speed data.

Interestingly, some strains of bacteria apparently increase anxiety in mice. In humans, one clinical trial found that ingesting the probiotic Lactobacillus casei actually improved the mood of participants.

So those bossy bacteria in your gut might think they’re in charge, but they can’t actually force you to do anythingthough they can make you really, really want to. 


The researchers who authored this study stress that because your gut’s microbiome changes so quickly depending on whether you choose to give in to its demands, implications for individuals with obesity, diabetes, and cancer are huge. Dr. Atkipis added,

“Targeting the microbiome could open up possibilities for preventing a variety of disease from obesity and diabetes to cancers of the gastro-intestinal tract. We are only beginning to scratch the surface of the importance of the microbiome for human health.”

We guess it all comes down to mind over gut bacteria.

[via CNET, UCSF]

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