How your diet affects your mood

They say you are what you eat, but exciting new research suggests otherwise: You feel what you eat. Scientists are focusing on psychobiotics, a type of bacteria found in certain foods that can produce and deliver important chemicals like serotonin to the brain. Their findings could mean a whole new approach to treating mental health issues, including depression and anxiety.

Psychobiotics are a subset of probiotics, bacteria that have made headlines in the last few years for aiding digestion and boosting the immune system. Today you can buy probiotic-rich yogurt, juice and even chocolate bars. Now it appears that some of these probiotics may also have a meaningful impact on mood disorders.

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The evidence for the power of these psychobiotics is preliminary but promising: In one study from University College Cork in Ireland, depressed rats swam more vigorously and their immune systems improved after ingesting a particular bacteria, Bifidobacterium infantis. Human results are scarcer, but a University of California in Los Angeles study found that women who ate yogurt with probiotics twice a day for a month showed distinct changes in a part of the brain related to emotions when scientists examined them using functional MRI technology.

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This increase occurs as a result of the so-called “brain-gut axis,” the connection between our brain and the billions of microorganisms that live in our digestive system. Whereas drugs like Valium reach the brain through the bloodstream, it’s believed that some key bacteria enhance the performance of mood-lifting neurotransmitters by sending a signal through the vagus nerve, which runs between the brain and abdomen.

So will cups of Activia someday replace Celexa at the pharmacy? Probably not. Ted Dinan, M.D., the Irish psychiatrist and researcher who coined the term psychobiotic, says they will need to be taken in larger quantities than occur naturally in food. That will mean swallowing pills, not just eating more yogurt.

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The kinds of major human experiments that would make such treatments mainstream are still in progress. But since natural bacteria generally cause fewer risky side effects than the powerful drugs currently used to treat mental illness, Dr. Dinan says the time frame for getting them to market will be much shorter than the typical FDA approval process. Meaning, the psychobiotic revolution may be here in just a few years.