Feeling anxious? Having a panic attack? Buried under a cloud of depression? You might want to try adding a few scoops of yogurt to your daily diet.
That’s the suggestion of a study published on August 29th, in the Proceedings of The National Academy of Sciences. Here, a group of Irish researchers found that probiotics or “good bacteria” (some of which are found in foods like yogurt) may have the ability to significantly impact the brain chemistry involved in stress, anxiety and depression.
“These findings highlight the important role that gut bacteria play in the bidirectional communication between the gut and the brain, the gut-brain axis, and opens up the intriguing opportunity of developing unique microbial-based strategies for the treatment of stress-related psychiatric disorders such as anxiety and depression,” said one of the study authors Professor John Cryan from the Alimentary Phamabiotic Centre in University College in Cork, Ireleand.
Doctors have long known that receptors for mood regulating chemicals such as serotonin are found in the stomach as well as the brain. More recently however, there has been a growing body of evidence suggesting that by manipulating the level of bacteria in the gut, you may also manipulate and change not just the expression of the neurotransmitters in the stomach, but also how those in the brain respond as well. This week's new study adds one more piece of evidence to the increasingly important puzzle of what causes anxiety and depression.
“This study indentifies potential brain targets and a pathway through which certain gut organisms [may] alter …brain chemistry and behavior,” says Cryan.
How the study was done
The study involved two groups of mice. In addition to their regular diet, over a period of 28 days one group of mice was given a plain broth, while the other group was fed a broth laced with a probiotic known as L.rhamnosus (JB-1). Probiotics are "live" cultures of bacteria that are thought to be healthy for our intestines.
Some of the mice also underwent a surgery to remove a portion of their vagus nerve – the direct connection between the gut and the brain.
Toward the end of the 28 day test period all the mice were subjected to a variety of behavioral tests designed to measure responses to anxiety, fear, and even depression. They also underwent a series of blood and other fluid tests to measure brain and body chemicals associated with these conditions, including coticosterone, a key stress hormone.
The result: The mice who received regular feedings of the probiotic were less likely to be anxious or stressed, even in stressful situations, than the mice who had the plain broth – but only if their vagus nerve was intact. These mice also produced lower levels of the chemitcal corticosterone, a key hormone that is not just secreted in response to stress, but which can also plays a role in triggering a host of "fight or flight" chemical responses frequently associated with anxiety, including panic attacks.
The mice who had their vagus nerve truncated responded much like the mice who did not get the probiotics – their anxiety and stress reactions were high.
Thus, not only did the study illustrate that probitoics could help change brain chemistry, it also illustrated these changes occured in a direct path from the stomach to the brain
Indeed, this study was also the first to demonstrate probiotics could impact the way the brain processes the key neurotransmitter GABA (gamma-Aminobutyric acid) which also plays a key role in the anxiety-depression axis.
The brain-gut connection
If you’ve ever had a queasy stomach before giving a speech, or got a case of the “runs” when you’ve had a nerve-wracking experience, then you’ve already experienced some of the links between the stomach, the brain, and anxiety.
But while many believed it was the emotional thoughts that triggered the stomach reactions, increasingly research indicates it may just be the other way around: The root of the anxiety may be in the stomach, with messages sent from here to the brain.
The messenger of these “bad vibes”: The vagus nerve, the direct link between the stomach and the brain through which bacteria in the gut to influences the activity in the brain.
The fact that the mice who had their vagus nerve removed didn’t get the benefits of the probitoics bears this theory out.
So how does it all work? The researchers believe that the presence of the probiotics helped to normalize the release of certain neurotransmitters in the brain – including GABA - that would naturally ebb and flow when we become stressed or anxious.
However, in those who suffer with anxiety problems, the “sensitivity” of these neurotransmitters may be greater, thus triggering a release of “fight or flight” chemicals, even when we aren’t in danger. This in turn leaves a “surplus” of hormones and other chemicals that, because our body doesn’t need them to “fight or flee” end up as anxiety attack.
The probiotics may work by helping to better regulate our brain chemistry so fewer "misfirings" occur - and this may help reduce our overall psychological and physiological reaction to stress.
Will eating yogurt help you feel better?
Remember that the study was conducted in mice, and not humans – and while our gastrointestinal systems are similar, we don’t know for sure if the reaction to probiotics would be the same.
We also don’t know if the strain of probitoic used in the test – L.rhamnosus (JB-1)- would work as well on humans as it did on mice, or if we might need a different type to elicit the same effect.
That said, there are a number of yogurts on the market that do contain live probiotic cultures including Stoneyfield (which contains 6 live cultures including the strain used in the new study) and Dannon, which contains at least two varieties of probiotics and may contain up to 5.
And since probiotics in general are good for your overall health, it certainly wouldn’t hurt to add some yogurt to your daily diet and see for yourself if it helps you feel less stressed and better able to cope.
There are also a variety of different probiotic supplements available at most health food stores including those made by Nature’s Way and Jarrow Formulas available at Swason Health Products.
Colette Bouchez is an award winning health and wellness journalist and the author of 10 medical books. Here latest is Eat, Love, Get Pregnant: A Couple's Guide To Boosting Fertility and Having A Healthy Baby - in bookstores beginning October 2011.
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