Bacteria in the stomach can "speak" to the brain to strongly influence food cravings, an Australian study has found.
The study, released by Monash University on Wednesday, revealed the first evidence of two species of bacteria that have an impact on dietary decisions.
Experiments conducted on a common fruit fly allowed the researchers to analyze the interaction between diet and microbes and its effect on food preference.
The scientists discovered that the flies which were deprived of amino acids showed decreased fertility and a stronger preference for protein-rich food.
Furthermore, two specific species of bacteria could abolish the craving for protein in the flies that were deprived of amino acids.
"With the right micobiome, fruit flies are able to face these unfavorable nutritional situations," study co-author Zita Carvalho-Santos said in a media release on Wednesday.
Patricia Francisco, a fellow author, said the complexity of the human system compared to that of the fly highlighted the importance of using simple animal models to gain insights into factors that could be crucial for human health.
"In the fruit fly, there are five main bacterial species, in humans there are hundreds," Francisco said.
Santos said the next step was to establish how the bacteria was acting on the brain to alter appetite.
"Our first hypothesis was that these bacteria might be providing the flies with the missing essential amino acids," she said.
However, the research disproved the hypothesis.
Instead, the gut bacteria "seem to induce some metabolic change that acts directly on the brain and the body, which mimics a state of protein satiety," Santos said.
