Over the past few years it has become increasingly clear that gastrointestinal (GI) bacteria play a variety of important roles in human digestion and overall health. The growing popularity of probiotic drinks and formulas indicate that the majority of us are aware of the importance of GI bacteria balance and gut health, but now scientists have proposed that GI bacteria also exert some control over appetite.
GI bacteria recognise and synthesise neuroendocrine hormones. The microbiota respond to both the nutrients consumed by their host and to the state of their hosts as signalled by various hormones. They also contribute to the generation of signalling compounds such as amino acid tyrosine and tryptophan which can be converted into mood altering molecules dopamine and serotonin. Mood has a distinct affect on appetite and further study is being conducted to establish whether GI bacteria inadvertently affects our food choices as well as our appetite.
Norris V, Molina F, Gewirtz AT, Hypothesis: Bacteria Control Host Appetites, Journal of Bacteriology, 2012.