Monday, June 11, 2012

Good Bacteria (Probiotics)

There’s another good reason to take probiotics, like those found in yogurt and fermented foods. Not only do they boost immunity and help ward off drug-resistant superbugs, but they could also help improve mood, new research suggests.

In a study done on mice, researchers at St. Joseph’s Healthcare in Hamilton and the University College in Cork, Ireland found that rodents fed a certain type of probiotic, or good bacteria, showed reduced signs of stress, anxiety and depression.

Probiotics are living organisms that inhabit the gut, keeping intestinal flora in balance and stimulating the immune response.

For 28 days, the mice were fed the probiotic Lactobacillus rhamnosus JB-1. The study, which was published this week in the Proceedings of the National Academy of Sciences, found that the probiotics affected neurotransmitter receptors, altering brain activity in the hippocampus, amygdala and prefrontal cortex. These are areas of the brain associated with mood.

 As well, the mice had less of the stress hormone corticosterone in their blood.

“This is the first-ever demonstration that harmless bacteria, found naturally in the intestine, can influence mood and behaviour in a normal animal,” said the study’s co-author Dr. John Bienenstock, director of the McMaster Brain-Body Institute at St. Joseph’s.

The findings suggest that changes in the gastrointestinal tract are communicated to the central nervous system via the vagus nerve, a long cranial nerve that extends from the brain to the abdomen. The discovery of this pathway is particularly significant Bienenstock said, explaining that electrical stimulation of the vagus nerve in humans has been shown to improve difficult-to-treat depression.

 “That is a clue to us that this is not just curing depression in mice, but there is some hope that this could eventually be applied to the human,” he said.Bienenstock hopes to get approval from Health Canada to conduct a clinical trial, using Lactobacillus rhamnosus JB-1 on humans.

Meantime, he is continuing to study the impact of the probiotic on mice, trying to determine exactly how it stimulates the nervous system.

“(The study) highlights the idea that bacteria in the intestine can influence certain mood and behavioural disorders and identifies the gut as a possible target for treatment,” Bienenstock said.

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