The definition of a probiotic, according to the WHO, is:
(And I am quoting, so don't hold me responsible for the lack of commas...)
"Live microorganisms which when administered in adequate amounts confer a health benefit on the host."
This is the question that some researchers at Acadia University Department of Psychology are addressing in a new study. They're recruiting subjects with anxiety and depression for a clinical intervention study called Probiotics and the Microbiome.
|Probiotic Lactobacillus acidophilus (Bob Blaylock, Wikimedia Commons)|
For ten weeks, the researchers will give participants 400 mg doses of acidophilus, bifidum, casei, plantarum, bulgaris, breve, and rhamnosus strains of bacteria. For another ten weeks, the researchers will give them a placebo. Participants won't know whether they're receiving the live bacteria or the placebo first.
It's not a mistake that the Department of Psychology is conducting the research, rather than a school of medicine. In fact, I think it's quite exciting that they need no medical professionals to be involved in a study that involves a kind of "pill". Health Canada considers probiotics a Natural Health Product, and as such, they do not require a prescription. If the study were to find a connection between probiotics and reduced symptoms of anxiety or depression, people could use this information to keep themselves well by doing nothing more than visiting their local health food store.
Meanwhile, the status of probiotics in the marketplace continues to be debated. Ostensibly, the goal is to ensure responsible clinical research and to prevent manufacturers from saying outrageous things on the labels, such as "probiotics cure alcoholism and all cancers." But under what circumstances should probiotics be considered drugs? Food additives? Foods?
For now, we can thank our lucky stars that it's not considered a drug. Otherwise, the clinical intervention trial would be a lot more complicated and the dear little Department of Psychology would be in over its head.
On the other side, though, some wish it would be considered a drug. Natural health product manufacturing is notoriously less regulated than drug manufacturing. I've spoken with several health professionals off-the-record (including one GI doc) who recommend probiotics to patients, but stay awake at night worrying about whether the patients are getting what the label says they're getting.
Let's leave that issue aside for a minute, though. The great part about this Acadia University research is that it may help uncover the "adequate amount" of microorganisms required for a potential benefit to mental health. And that could help a lot of people in their daily lives - including those with only mild symptoms of anxiety or depression who don't have a formal diagnosis.
Limitations of the study include the fact that - whatever the result - the results will be a drop in the bucket. If the researchers observe a positive effect, the results will only hold for those particular strains at that dose. If the researchers observe no effect, it's still possible that other strains or doses (yet unstudied) would be effective. Regardless, I'll be awaiting the result. (Non-anxiously, though, since I'm taking my own probiotic on a daily basis.)
For a great overview of the gut-brain connection, try Michael Gershon's book, "The Second Brain."