In the first study of its kind, Canadian researchers are investigating whether probiotics, the good stomach bacteria that aid digestion, regulate the immune system and reduce inflammation, may in fact be a treatment for those with bipolar disorder.

Human guts contain 400 different kinds of probiotics, and health food store shelves are filled with different brands to help keep them at optimal levels.

Researchers at Women’s College Hospital in Toronto are studying probiotics versus a placebo in 50 patients with bipolar disorder. The patients stay on their medication over the eight-week trial, and researchers are studying whether the probiotics help further stabilize their illness.

Probiotics are “a novel area for exploration” for treating mental illness, researcher Dr. Valerie Taylor, a psychiatrist at Women’s College, told CTV News.

The key to improving treatments, and the lives of those suffering from mental illness, may lie in “looking outside the box and other body systems,” Taylor said.

“There may be something (with probiotics) that is worth exploring and we'll never know unless we try,” she said.

So far, animal studies offer hope.

Last year, researchers at St. Joseph’s Healthcare in Hamilton, Ont., discovered that mice that were stripped of their good stomach bacteria became anxious and depressed.

When they were given a probiotic, the animals’ moods improved as chemicals that reduce anxiety flooded their brains.

Those findings showed that “it is possible to simply feed a bacterium and then actually change the chemistry in the brain,” Dr. John Bienenstock, director of the Brain-Body Institute at St. Joseph’s, told CTV.

The treatment possibilities of over-the-counter probiotics are “unbelievable” should the human studies reach the same conclusions as the research in mice.

“Psychiatry may well find that there are many factors in the intestines that promote the expression of anxiety, depression, and so on,” Bienenstock said. “So looking inside the brain only is not the only way of looking at things. This is a revolution in itself.”

As for research in humans, the only study into how probiotics affect brain chemistry has been conducted in healthy people.

The Women’s College study furthers that research by looking at individuals who already have a diagnosis of depression or bipolar disorder.

Because probiotics reduce inflammation in the body, they may treat depression or anxiety in two ways. Researchers from the Centre for Addiction and Mental Health recently found brain inflammation in patients with depression. The greater the inflammation, the more severe the patient’s symptoms, they reported.

In addition to regulating stomach bacteria, the probiotics could help reduce that brain inflammation.

While the Women’s College team is still hoping to recruit more patients to their study, one participant said she likes the fact that researchers are looking into probiotics as a supplement to drug therapy.

“I am happy they are just exploring different possibilities because I was really upset that I had to rely on medication,” Jeanetta, who did not want her last name used, told CTV.

The researchers should have the first results from their study later this year.

“If it just works for a small group of clients, that is a small group of clients that will have access to novel treatments that are a little more tolerable than some of the things we have now,” Taylor said.

With a report from CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip