Has anyone ever tried to trick you by asking “What is the most populous cell in the human body?” More than likely, the person asking this was a young child, as they always seem to find quirky questions like these the funniest. After digging into the back of your brain for something that you probably learned in elementary school, you may come up with a very reasonable answer: red blood cells. However, this answer to the child’s joke would be wrong. The child cleverly answers back “Actually, they aren’t cells made by the human body at all! They are the bacterial cells that inhabit our guts!”
True, the bacteria that reside in our intestines are on the order of 100-fold greater in numbers than any other cell in the body. This begs the question of if they have any influence over the workings of our bodies. We know that the bacterial cells are important to our digestion and live in a symbiotic relationship with ourselves. Recent studies are showing that the bacteria also play a role in our appetites and our cravings. How can such tiny organisms have such great influence?
Scientists have only recently begun to appreciate the magnitude of the bacteria in our gut and the interplay between us and them. Because our digestive tract is intimately connected with our bloodstream and our lymphatic system, it is possible that bacteria release chemical signals that can travel to our brains and influence the types of foods that we next choose to eat. Bacteria are also known to produce toxins after certain foods are eaten that cause us to feel ill. This will definitely influence our choices in the future! Even more interesting is research involving the vagus nerve. This is the 10th cranial nerve that enervates the stomach, providing a direct connection between the digestive tract and the brain. Scientists believe that bacteria can produce chemicals that act upon the brain through this conduit, too!
The composition of the bacteria in our guts differ based on the foods that we eat. Some digest sugars more readily while others prefer fats. Some are even as specific as to digest cultural delicacies that are only found in certain parts of the world (and therefore, only the guts of those living in those regions). As our diets change, so do the bacteria in our intestines. Future endeavors for scientists will be to investigate changing diets and the incorporation of probiotics to alter the bacterial flora. Will this cause cravings to change? Only time will tell.
Article Source: University of California, San Francisco (UCSF). “Do gut bacteria rule our minds? In an ecosystem within us, microbes evolved to sway food choices.” ScienceDaily. ScienceDaily, 15 August 2014.
Image Source: PNNL. “Improving Human Intestinal Health” 26 September 2012 via Flickr. Creative Commons Attributions.