QUESTION: “Hey Dr. Neal, I was wondering if you could revisit the topic of the the microbiome, recent research, and the benefits and disadvantages of tests promising to analyze one’s gut health. I have been researching and considering purchasing a test to better understand my gut health, which foods my body would prefer me not to eat, as well as what food, vitamins, etc. may be missing from my diet. Any insight would be great! Love the show and your consistency and consideration you provide in the commentaries.”
DR. NEAL: Thank you so much for taking the time to send in your question. I am thrilled that you enjoy the podcast and find it so helpful.
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One of the biggest challenges when studying the microbiome is actually trying to define it. Even those that specialize in studying it aren’t really sure how to define it (or even what to call it). Some use the term microbiota as a synonym for the microbiome.
What we can agree on is that, first, we’re talking about the good bacteria found in the gut. And we’re talking about LOTS of them; it is estimated that each person has anywhere from 10-100 trillion of these good bacteria in our intestines. These are good bacteria – they help keep us healthy.
What’s amazing is that each person’s microbiome is different. There are lots of different strains or species of these good bacteria within each person, but in different quantities. It is believed there are at least 400 different species of these good bacteria within each person. It’s these different quantities that make everyone’s microbiome unique to each person.
Researchers can agree that it is always a good idea to try to preserve the health of your gut. Now, what if there was some way for us to know what our microbiome is made of? Meaning, how many good bacteria and the specific species of good bacteria there are in our gut? Would that be useful? Would this information even be accurate? Well, that’s basically what Brad was asking. So, let’s find out…
How is the Microbiome Tested?
Some doctors have ways to test for this and there are even tests that you can buy for use at-home… all with the aim of determining what your gut microbiome is composed of. The way these tests work is that they analyze your fecal matter (also known as stool). It is estimated that just 1 g of stool contains 100 billion microbes.
So, by sending the lab a small sample of stool, they can supposedly detect what your microbiome is made of. But the problem with these gut microbiome tests is that they are really new. This means that, yes, labs may be able to guesstimate the number and types of good bacteria in your gut. But interpreting this information and providing recommendations based on these results is another issue altogether. One problem is that there aren’t any established reference ranges.
I’ll give you an example. Say you go to the doctor and get a blood test. When the results of the test come back, your doctor may say something like, “You’re doing great. Your cholesterol levels are looking really good.” How does the doctor know that your cholesterol levels are good?
Well, there are established reference ranges. You’ve probably seen these ranges before. When you get the results of the lab tests, there’s always that extra column that tells you what the “normal” values should be. These are the reference ranges. When your values fall above or below these reference ranges, the doctor would provide guidance about how to get your lab values back in these reference ranges.
What Do These Microbiome Tests Really Tell Us?
The trouble with these new gut microbiome tests is that there aren’t any of these reference ranges. Health professionals may not be sure how to interpret the results. For example, the results of these gut microbiome tests may tell us which species of good bacteria are found in your gut but doctors may not know what each specific species of bacteria is responsible for.
Which ones help with promoting the health of the immune system overall? Which ones help us better digest the foods we eat? How do different species of bacteria interact and help each other? All of this information is unclear at this point.
Oh, and the other problem is that our gut microbiome is constantly changing – the number and species of good bacteria change all the time. And finally, health professionals aren’t even agreeable on whether our stool is the most accurate representation of our microbiome.
The Bottom Line
What we do know at this point is that these good bacteria in our gut promote health. But how many of each species we need, understanding how each species interacts, what each is responsible for… and so on is still a mystery.
So, most health experts agree that for now, save your money on these microbiome tests until we know more about how to interpret these results.