Common probiotics may reduce stress, anxiety: study

A common probiotic sold in supplements and yogurt may decrease anxiety and stress-related behaviour, a new study has claimed.
Probiotics, or beneficial live bacteria that are introduced into the body, have become increasingly popular as a way to improve health and well-being, researchers said.
Previous studies have shown a direct correlation between gut microbes and the central nervous system.
Now, researchers at the University of Missouri (MU) in the US, using a zebrafish model, determined that a common probiotic sold in supplements and yogurt can decrease stress-related behaviour and anxiety.
"Zebrafish are an emerging model species for neurobehavioral studies and their use is well-established in drug-screening," said Aaron Ericsson, director of the MU Metagenomics Centre.

"Our study has shown that simple probiotics that we normally use to keep our digestive tract in sync, could be beneficial to reducing our stress levels as well," said Ericsson.

In a series of studies, researchers tested how zebrafish behaved after doses of Lactobacillus plantarum, a common bacteria found in yogurt and probiotic supplements.
In the first study, scientists added the bacteria to certain tanks housing zebrafish; other tanks of zebrafish received no probiotics.
Then, the researchers introduced environmental stressors to both groups, such as draining small amounts of water from the tank and overcrowding.
"Each day we introduced a different stressor - tests that are validated by other researchers and cause higher anxiety among zebrafish," said Elizabeth Bryda, professor in the MU College of Veterinary Medicine.

"These are common environmental stress patterns, such as isolation stress and temperature change, so it made the tests relevant to humans as well," said Bryda.
By analysing the gene pathways of both groups of fish, the research team found that zebrafish that were given the supplements showed a reduction in the metabolic pathways associated with stress.
"By measuring the genes associated with stress and anxiety, our tests were able to predict how this common probiotic is able to benefit behavioural responses in these fish," said Daniel Davis, assistant director of the MU Animal Modeling Core.
"Essentially, bacteria in the gut altered the gene expression associated with stress- and anxiety-related pathways in the fish allowing for increased signalling of particular neurotransmitters," said Davis.

The study was published in the journal Scientific Reports.