The inconclusive science behind probiotics
Illustration by Chloe Latour.
With the explosion of interest in the microbiome and gut health, most people are aware of the bacteria and other organisms living in their body. This area of science has been super trendy recently, and for good reason. The human microbiome may have large-scale effects on mood, cancer risk, and even life span.
Entrepreneurs have recognized this, and have produced a wide array of products and services claiming vaguely to ‘improve’ your microbiome. However, for many consumers, this influx of health-promoting products begs the following question: do these products really work?
First, a short introduction to the human microbiome. It’s not just the bacteria that live in our intestines. On nearly every surface of your body, internal and external, there is a symbiotic community of bacteria, fungi, viruses, and other organisms. Diverse communities exist in your mouth, on your skin, and of course in your gut, and the composition varies from site to site.
Our microbiome is generally beneficial, and assists with many necessary bodily tasks like digestion, defence against infection, and production of beneficial nutrients. The type of bacteria present in your gut depends on your lifestyle, genetics, and environment. The foods you eat and the medications you take have major roles in shaping your bacterial composition. All of this variability leads to a pain in the neck for scientists. Researching this unique part of the human body is very complex.
What scientists are still not sure of though, is the ability of probiotics — edible supplements of live, beneficial bacteria — to benefit all people who take them.
Touted for their gut-healing abilities, supplements containing probiotics have received a lot of attention lately. One way that our bodies oppose these products is something called colonization resistance, a process by which already established bacteria in your gut resist the attempts of new, foreign bacteria to set up shop. Colonization resistance, like many other facets of the microbiota, varies from person to person. Probiotic supplements stick around in some people’s guts, but get flushed through others. So how do you know if your microbiome is going to be partial to these probiotics or not?
If we could see the bacterial composition of the intestinal microbiome, we could be able to solve some of the problems associated with microbial differences. From this data, we could determine if the microbes present are permissive of or resistant to colonization by probiotics.
Thankfully, scientists do have a method like this at their disposal. Microbiome sequencing is an emerging tool that has caused a major stir in the scientific community. This technique has given us the ability to probe an individual’s gut microbiota to see the full genome of the microbes that are present.
One of UVic’s resident experts on the human microbiome, Dr. Lauren Davey, is a professor in the biochemistry and microbiology department. Her class, Microbiota and Human Health, provides a host of engaging information, from microbiome basics to emerging discoveries in the field. I reached out over email to hear her thoughts about these trendy probiotic products.
“Commercial probiotics and microbiome sequencing services are often expensive, and while they can offer a peek into our gut health, the ability to turn this data into personalized advice isn’t quite there yet. The field is rapidly evolving, but realistically, we’re about five years away from confidently using this information to improve health outcomes. The potential is huge, but the science hasn’t caught up yet.”
It seems like sequencing may not be the answer, but other emerging areas of science could tell us if our guts are susceptible to probiotics. A way that scientists are trying to address the complexities of the microbiome is with machine learning. Using an artificial gut and an algorithm, researchers are predicting what probiotics can be successful, without needing any experiments at all.
Additionally, current research is looking into the ingestion of a probiotic with a prebiotic (food that you can’t digest, but bacteria can) as a way of increasing colonization. These are known as ‘synbiotics’, and are being investigated as a potential treatment for conditions like diabetes and arthritis.
So then what’s our consensus? Can probiotics contribute to a healthy lifestyle and fix all of our problems? The short and unfulfilling answer is maybe, but we’re not completely sure yet. For some people, the answer may be yes. Because of the massive amount of variance from person to person, proof of probiotic efficacy is hard to nail down.
Like many areas of science, microbiome research is uncovering new advances all the time, and though there have been some promising results, nothing is conclusive yet. As for right now, you probably don’t need to run to your local pharmacy and shell out for a pricey supplement. Instead, maybe just settle for a few bites of Greek yogurt.
