Probiotics have been receiving considerable attention lately due to their potential health benefits. These live bacteria, found in fermented foods, yogurt, and supplements, are associated with various health advantages, such as reducing gastrointestinal distress, urinary tract infections, and eczema. However, can they also improve one’s mood?
The relationship between behavior, mental health, and probiotics is complex. However, recent research by the team suggests that the answer is likely yes.
Probiotic bacteria become part of a diverse community of microscopic organisms in the human gut known as the gut microbiome. This microbiome consists of trillions of bacteria, fungi, and viruses.
The gut is home to hundreds of bacterial species, each with numerous strains that differ in metabolism, byproducts, and environmental preferences. This diversity is important because not all probiotics are the same. Studies have shown that specific Lactobacillus strains can have mood-enhancing effects.
However, these effects depend on the right mix of bacteria and conditions. For example, a probiotic that reduces stress in someone preparing for an exam may not be effective for someone with post-traumatic stress disorder.
As a neuroscientist, the researchers investigate how the gut affects the brain. Recent experiments in mice support the idea that the gut microbiota plays a role in regulating stress.
To measure the mood of mice, the researchers first needed to understand how stress affects their behavior. The mice were subjected to short periods of stress, similar to being confined in a car or office for hours. Stressed mice showed signs of depression and anxiety, such as hiding and slow reactions.
What surprised the researchers was the impact of the mice’s feces on their behavior. To see if stress-related behavior could be transmitted through the microbiome, clean mice (without any microbiome) were exposed to feces from stressed or normal mice. The clean mice exposed to stressed mice’s feces developed stress and anxiety-like behavior, while those exposed to normal mice’s feces showed no changes.
Further analysis revealed that stressed mice had lower levels of a bacteria group called Lactobacillus, which is associated with stress reduction. However, Lactobacillus comprises over 170 species and even more strains.
To determine which strains affect mood, the researchers created a method to systematically test different Lactobacillus strains in mice. Two strains, Lactobacillus intestinalis ASF360 and Lactobacillus murinus ASF361, were found to make mice more resilient to stress and reduce neural pathways associated with fear.
This study is just the beginning. The researchers hope that their research will inspire other scientists to explore different probiotics. While it’s becoming clear that gut bacteria can influence mood, more research is needed in both animals and humans.
In the meantime, supporting Lactobacillus in one’s gut with a healthy, probiotics-rich diet may be beneficial.
