It sounds like science fiction, but it seems that bacteria within us — which outnumber our own cells by approximately 100-fold — may very well be affecting both our cravings and our moods to get us to eat what they want, and often are driving us toward obesity. In an article published online on August 7, 2014 in the journal BioEssays, researchers from the University of California-San Francisco, (UCSF), Arizona State University, and the University of New Mexico concluded from a review of the recent scientific literature that microbes influence human eating behavior and dietary choices to favor consumption of the particular nutrients the microbes grow best on, rather than simply passively living off whatever nutrients humans choose to send their way. Bacterial species vary in the nutrients they need. Some prefer fat, and others sugar, for instance. But they not only vie with each other for food and to retain a niche within their ecosystem — our digestive tracts — they also often have different aims than we do when it comes to our own actions, according to senior author Athena Aktipis, Ph.D., co-founder of the Center for Evolution and Cancer with the Helen Diller Family Comprehensive Cancer Center at UCSF. While it is unclear exactly how this occurs, the authors believe this diverse community of microbes, collectively known as the gut microbiome, may influence our decisions by releasing signaling molecules into our gut. Because the gut is linked to the immune system, the endocrine system, and the nervous system, those signals could influence our physiologic and behavioral responses. "Bacteria within the gut are manipulative," said Carlo Maley, Ph.D., director of the UCSF Center for Evolution and Cancer and the corresponding author on the BioEssays paper.Login Or Register To Read Full Story