Gut Bacteria Influences What You Choose To Eat

Is Your Gut Bacteria Ruling Your Brain on Food Choices?

Some scientists are arguing that gut bacteria are responsible for manipulating eating behavior by causing cravings for food they favor for fitness or that suppress their competition.

Alternatively, gut bacteria may send out signals via the vagut-bacteria-imagegus nerve to the brain to leave a person to feeling an overall uneasiness and even depression which may then cause people to eat what the bacteria “needs” whether it’s good health or not, a diverse group of researchers are suggesting.

“Bacteria within the gut are manipulative,” Carlo Maley, PhD, director, Center for Evolution and Cancer, University of California at San Francisco, states in a press release. “There is a diversity of interests represented in the microbiome, some aligned with our own dietary goals and others not.”

In their overview of eating behavior and the microbiome published online August 7, 2014 in BioEssays, Joe Alcock, MD, University of New Mexico, Albuquerque, and colleagues argue that certain gut bacteria are highly dependent on the nutrient composition of the diet.

For example, the gut bacteria Prevotella grows best on carbohydrates while dietary fiber provides a competitive advantage to the gut bacteria Bifidobacteria.

“Even microbes with a generalist strategy tend to do better on some combinations of nutrients than others,” the authors write, “and competition will determine which microbes survive.”

Microbes can manipulate host behavior in a variety of ways, but one way may be by “hijacking” the host’s nervous system. As the authors point out, evidence shows that microbes can have dramatic effects on behavior through the microbiome-gut-brain neurological axis.

“The vagus nerve is a central actor in this communication axis, connecting the 100 million neurons in the enteric nervous system (nervous system of our gastrointestinal tract) in the gut to the base of the brain at the medulla,” they explain.

The enteric nerves have receptors that react to the presence of particular bacteria as well as to bacterial metabolites.

Research has also shown that blocking or cutting of the vagus nerve causes drastic weight loss while stimulation of its activity through the adrenal hormone norepinephrine appears to drive excessive eating behavior in satiated rats.

Another neuronal pathway through which microbes may influence our eating behavior is through secretion of hormones involved in mood and behavior, including dopamine and serotonin.

Microbes may also manipulate eating behavior by altering receptor expression. Changes in taste receptor expression and activity have been reported following gastric bypass surgery, a procedure that changes gut microbiota and alters satiety and food preference, as the authors point out.

“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,” coauthor Athena Aktipis, PhD, Arizona State University, Phoenix, states in a press release.

“Together, these results suggest that microbes have opportunities to manipulate vagus nerve traffic in order to control host eating. Exerting self-control over eating choices may be partly a matter of suppressing microbial signals that originate in the gut.”

The use of antibiotics severely damages the guts microbiota, killing off and altering the bacteria that colonize our bodies.

Happily, researchers add, the use of prebiotics, probiotics and dietary changes can rapidly alter the intestinal microbiome within 24 hours of administration.

If you suffer from weight related issues or other health issues of the GI tract contact Dr. Walter K. Crooks to schedule a workshop so that you may learn more about how to improve your gastrointestinal health naturally.


BioEssays. Published online August 7, 2014. Abstract