The mice were divided into two groups with one group being a control group which ate regular mice feed, and the other being a test group which ate a healthy strain of bacteria called
lactobacillus ramnosis which is frequently added to natural yoghurt.
Dr Cryan also discovered the mechanism; that
the lactobacillus ramnosis group had far higher levels of a sedative neurotransmitter called GABA, which prevents cortisol from spiking too high.
Compared to the rats fed
the lactobacillus ramnosis bacteria, the standard mice - feed rats had approximately 100 times more cortisol in their bloodstream.