In a study of bacteria, mice were cured of depression and anxiety with probiotics. It reminds me of an earlier experiment done on humans showing that people who took probiotic supplements felt less stressed and had less anxiety and depression than people who had taken a placebo.
In the more recent study, researchers took normal mice, which are usually fairly timid (staying close to walls when they explore and being reluctant to walk in the open). They fed half the mice a brew containing a particular strain of gut bacteria — Lactobacillus rhamnosus (a strain found in some yogurts and probiotic supplements) — and the mice became less timid; they explored more freely.
And when the researchers put the mice under stress (by plunging them in water, for example), the “probiotic mice” were less stressed than normal mice (the stress hormones in their blood didn’t rise as much in response to the stress). You can read more details about the study here and here.
But the researchers wondered how a bacteria in the gut could alter the mice “psychologically.” So they cut the vagus nerve — the bundle of nerve fibers that connect the guts and the brain — and sure enough, this stopped the positive effects of the probiotics.
So somehow the bacteria did something to the mice guts that sent a signal through the vagus nerve to the brain, causing the mice to feel (or at least behave) less anxious and depressed, and to produce less stress hormones.
Probiotics are also good for your immune system, can help prevent gum disease and cavities, and might lower your risks of cancer and heart disease. Read more about how you can use probiotics to improve your health and mood here: Why Are Probiotics Good For You?
Adam Khan is the author of Antivirus For Your Mind: How to Strengthen Your Persistence and Determination and Feel Good More Often and co-author with Klassy Evans of Viewfinder: How to Change the Way You Look at Things.