Feeling Down? Try Some Yogurt

[Buster's Uncle]

Feeling Down? Try Some Yogurt
US News
By Beth Howard  2 hours ago



Yogurt ads promise that ingesting active bacteria cultures will help keep you regular, and probiotic capsules are said to keep the system defended by healthful bugs when a course of antibiotics threatens the good ones along with the bad. But the benefits of attending to the bacteria in your GI tract may go well beyond preventing turmoil there. A growing body of research suggests that the health of the bug-rich environment below the belt may have profound effects above it, in the brain.

If borne out in people, recent insights from animal studies could eventually lead to new treatments for stress, mood disorders and perhaps even mental illness, says Stephen Collins, associate dean of research at McMaster University in Hamilton, Ontario, where scientists have shown that altering the gut bacteria in mice changes both their brain chemistry and behavior. Mice bred to lack gut bacteria, for example, unlike typical "cautious and apprehensive" mice, turned out to be "risk takers," says Collins. "They showed no anxiety at all." When given bacteria that normally inhabit the mouse gut, they became more careful. And when a shy strain of mice was colonized with bacteria from a more assertive strain, the group showed greater confidence in performing tasks.

A number of findings in people seem to confirm this relationship. A study from Australia's Swinburne University of Technology found that stool samples of students collected during exams contained fewer of the beneficial bacteria lactobacilli than during less stressful times. "Bacteria influence the brain, and the brain influences bacteria," says Mark Lyte, a professor in the department of immunotherapeutics and biotechnology at Texas Tech University, whose work with colleagues there and at Ohio State showed that mice forced to share a cage with more aggressive types had fewer healthful gut bacteria.

This synergy may help explain why so many people with GI conditions such as irritable bowel syndrome and ulcerative colitis also battle depression and anxiety. Research has also found that the bacterial composition in the intestines is different in some children with autism spectrum disorder, though "we're not certain that changes in the microbial environment cause behavioral changes or are secondary to it," says Collins. Researchers at the Sheppard Pratt Health System in Baltimore are currently studying whether probiotics could help prevent episodes of mania in people with bipolar disease.


The Second Brain

Scientists have long known that the GI tract is home to the enteric nervous system, or "second brain," thousands of nerves dependent on the same neurotransmitters that operate in the actual brain: GABA, which has valium-like effects, and serotonin, which helps regulate mood. (The gut, in fact, produces 95 percent of the body's serotonin.) The two centers appear to communicate via these neurotransmitters and the vagus nerve, which runs between the brain and the abdomen. "We hope that by understanding the link," says Collins, "we can start to identify novel ways to treat behavioral problems."

Meantime, might probiotics help depressed and anxious people feel different? That's an open question. Last year, UCLA researchers took a step toward an answer, giving healthy women a probiotic-rich yogurt drink for four weeks. Brain scans at the start and end of the period showed that circuits associated with emotion recognition were less reactive after consuming the drink, says senior study author Emeran Mayer, director of UCLA's Oppenheimer Center for the Neurobiology of Stress. While treatments are years away, some scientists envision a day when people are prescribed "psychotropic microbes" to improve all sorts of brain disorders and mental woes. Until then, occasional smoothies can't hurt.


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