Jane A. Foster, PhD, and Scot Bay, MD: Influence of the Microbiome on Mood
Interview by Craig Gustafson
Scot Bay, MD, is board certified in adult psychiatry. He was educated at the University of Rochester and New York Medical College. He completed his residency in psychiatry at St. Vincent’s Hospital in New York City. Dr Bay specializes in the evaluation and management of mood, anxiety, and thought disorders and has special interests and expertise in psychopharmacology. He has extensive experience with numerous psychiatric medications and has lectured all over the Southeast regarding practical and innovative uses of psychiatric medications.
Jane Foster, PhD, joined the McMaster University faculty in 2003. She holds a research appointment with the University Health Network in Toronto, Ontario, Canada, as well as a scientific position with St. Michael’s Hospital. Dr Foster is an active researcher with two translational networks, The Province of Ontario Neurodevelopment Disorders Network (POND) and the Canadian Biomarker Integration Network in Depression (CAN-BIND). Her research focuses on the role of immune-brain and gut-brain interactions on neurodevelopment, behavior, and brain function.
InnoVision Professional Media (IVPM): Regarding those differences from individual to individual in microbiome composition, Dr Foster, you have said that people are 98% or 99% the same from a genetic standpoint, but only about 10% the same from a microbiome standpoint?
Dr Foster: Yes. That is based on the Human Genome Project. Essentially all our genes line up identically. We have snips and variations, but the way our genome is organized is pretty similar. With respect to the microbiome, we are only 10% similar. That was actually a bit of a surprise, once all this started coming down the pike, and it is the basis of projects such as the Human Microbiome Project, and the MetaHIT project. Now there are a few other big consortiums, and these really drove the field to consider what a healthy microbiome is.
Diet is a big player. It's a small player when it comes to what your bacterial composition is, but when it comes to the function of those bacteria that are there and we start looking at metabolism, diet is a big factor on how the bacteria you have behave. One of the biggest factors that people were surprised about was geography. When people started researching what a healthy microbiome is, a lot of the big data came only from the United States. A couple of key papers [looked at] rural communities, or communities that haven't yet been urbanized, and they all have their own microbiome. So in order to take into account the population effect, we have to broaden the scope in how we think about these things.
We know that big individual differences exist, and people have started to [investigate], "Is that because we first have to take this category and sort people into these unique profiles?" There has been some clustering work on that, and there is some consensus that there are some profiles of microbiome. Some of that work comes from comparing vegetarians to omnivores, where there are some key bacteria that seem to be much more prevalent if you have a vegan diet. But again, that is within the healthy population. Like everything else, we have to understand what is driving these systems in a healthy person before we can figure out why it matters in an unhealthy person.
IVPM: If a wide diversity exists in microbiome composition from individual to individual, how do you go about employing a probiotic in order to affect a change in health?
Dr Bay: Certainly like anything else, [a particular intervention] is not going to work for everyone who takes it. But as far as how you choose [a probiotic to use for a given condition], the whole way that I came at this was reading the research, the paper where that [probiotic] was described.
We can talk about an example of a particular probiotic, the Target gb-X (Klaire Labs), which was tested to see how it would affect a key symptom in people who suffer from depression. It was tested in people who were not depressed, but it was found to be helpful with aggressive, negative, self-critical ruminations. That's one of the core symptoms of major depressive disorder. Even though, again, it was tested in healthy patients, it decreased that symptom. The species they chose to include in the blend were designed to attack all the [typical] problems, like preserving the integrity of the epithelial layer, preventing the effects of inflammation, and promoting adequate production of neurotransmitters.
IVPM: So after reading the literature, you saw some synergy with the patients you were seeing in your practice and decided to give it a try?
Dr Bay: Absolutely. I thought, "Well, if this probiotic can affect mood-related symptoms, I have so many people who, despite really aggressive psychotropic medication regimens, are only marginally better. Let's give it a try." So [I began] combining it with psychotropic medications to treat mood disorders and also some anxiety disorders, too. I also have been using it in people with comorbid gastrointestinal symptoms, although I've been trying to expand that to people who don't have comorbid, coexisting gastrointestinal disorders. But, certainly, those are the people I target first to see if they would improve.
IVPM: And what did you see?
Dr Bay: I saw notable improvement in both types of symptoms. At least noticeable, slight improvements in mood as well as improvement in gastrointestinal symptoms, be that irritable bowel syndrome, chronic constipation, chronic diarrhea, or gastroparesis. It seems to be a good fit in psychiatric patients who have had limited response to medications and also have comorbid gastrointestinal symptoms.
IVPM: It is my understanding that when you began using the probiotic you focused on people who exhibited signs of medication resistance. Have you had opportunities to try it with less problematic cases?
Dr Bay: Yes, in fact, there was at least one patient in my original case series who wasn't overly resistant to medication, fairly responsive to it, but did have an unusually high tolerance to it and required an unusually high dose. In other respects it wasn't what I would classify as medication-resistant. Polypharmacy was not required to achieve benefit from the medication, and she responded to it pretty well. She had chronic IBS and those symptoms improved. And I've given it to some other patients and they've also been pleased with it.
The reason that original case series looked like a whole bunch of really tough, treatment-resistant patients [is because] there was a question of scarcity of resources. I had a case of it shipped to me from the company in the Netherlands, so I only had a limited supply, and I just decided to give it to the most difficult [cases]. But since it became available in the United States, I've certainly expanded beyond that type of patient.
IVPM: And you're seeing similar results?
Dr Bay: Yes.
Dr Foster: One important thing that Dr Bay touched on is that from an evidence-based perspective it seems that the strain matters. So, in a particular formulation, like Target gb-X, it's got a series of bacteria that are a specific substrain on that label. So from an evidence perspective, and the reason why I think it was so attractive to Dr Bay, that formulation was targeting a symptom that he was interested in treating.
The International Society of Prebiotics and Probiotics and other groups that try to keep the science real in this domain like to emphasize the fact that the evidence suggests that formulation works for what it was tested on, specifically, and it is not generalizable outside of that. That doesn't mean every product on the market that has these labels is going to have the same impact. It's possible, but we really do think the science, the evidence, needs to be strengthened for some of the most actively used. And there are some resources online that list the evidence for these types of products.
There's a database both on the Canadian side and on the US side that summarizes the evidence for all of the probiotics on the market, that there's any evidence for, from a good-to-bad evidence level, or some evidence to a lot of evidence. And that is updated regularly. When I talk to families they always [ask], "What probiotic?" So I talk about the benefits, the mood one is generally Target gb-X, which [has effects] that have been demonstrated. For other problems like intestinal inflammation and some of the more gut-related things, there are quite a few on the market that have demonstrated [effects]. Lots [exist] for women's health, too. It's important for people to understand that it's a very dynamic thing, and that the evidence supports specific products for specific uses at this point. That doesn't mean [these strains or products] are not going to have other benefits. But [one product] is not a panacea that's going to work for everybody.
Dr Bay: That's a fantastic point, Dr Foster. Specifically [with regard to] the species Bifidobacterium and [its] subspecies, I have seen other literature even before seeing Dr Steinbergen's article—which is the one I mentioned before, where they [tested it on] healthy folks and founded the Target gb-X product. The original manufacturer, Winclove Probiotics in the Netherlands, called it Ecologic Barrier. That particular species caught my eye, because I'd seen literature from other sources in the past where there were findings about probiotics and mood. This particular species had also been mentioned there. As far as diving more into how Winclove developed the product, they actually included very specific subspecies specifically to target mood symptoms. So again, I think that adds to how [products can be] specifically tailored to help with mood.
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