According to the National Institutes of Health (NIH), roughly 18 percent of American adults summer from an anxiety disorder and about seven percent suffer from major depression. Recent research has focused on substantiating inflammatory models of mental illness, including markers that indicate immune distress. That research has led to the conclusion that “good” bacteria found in probiotics can have a significantly positive effect on mental health.
We already know that probiotics are beneficial for healthy digestion, can alleviate eczema and relieve allergy symptoms. But the extent of their impact goes well beyond the gut. Scientists now recognize the amount of communication that goes on between the gut and the brain. This should come as no surprise with everyday phrases such as a “gut instinct” or bravery translated as being “gutsy.” When we’re feeling nervous, we often describe the feeling of “butterflies in our tummies.”
In a groundbreaking study, John Cryan, a professor of anatomy and neuroscience at University College Cork in Ireland, studied the effects of Lactobacillus on mice. Lactobacillus is one of the most commonly used probiotics. Cryan gave the probiotic to a group of mice every day for a month to see if their behavior changed. They found that compared to mice fed just regular broth, those receiving the probiotic were significantly less anxious. In his words, “They behaved almost as if they were on Valium or Prozac.”
A more recent study published in the journal Brain, Behavior, and Immunity found more compelling evidence to support probiotic use and decreased depression. Researchers from Leiden University reported that among 40 healthy subjects, those who unknowingly underwent four weeks of probiotic treatment showed a decrease in negative thoughts and feelings. Lead study investigator, Lorenza S. Colzato, said “…our findings shed an interesting new light on the potential of probiotics to serve as adjuvant or preventive therapy for depression.” While the research on humans and probiotics is still in its infancy, the current study provides evidence that the intake of probiotics may help reduce negative thoughts associated with depression.
Scientist aren’t yet sure how probiotics reduce negative mood, thoughts and feelings, but it’s possible that they increase levels of plasma tryptophan. Plasma tryptophan is a neurochemical involved in mood and emotions and is found in the gut. Research suggests these neurochemicals reach the brain by way of the vagus nerve. Probiotics also help control unwanted inflammatory responses in the immune system and inflammation has been previously linked to depression.
So, should you be taking probiotics to treat your depression and anxiety? Experts agree that more research is needed. But it certainly can’t hurt to try (they offer so many other health benefits) under the guidance of your physician.