There are trillions of microbes living in and on our bodies. Bacteria, fungi, viruses and other microorganisms. And a growing body of evidence indicates that these bugs aren’t bad for us. In fact, it looks like they’re vital for our health.
MEGHNA CHAKRABARTI, HOST:
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Let's talk about one of the hottest field in biomedical research these days, the trillions of microbes that live in and on the human body. That's right, your body. Bacteria, fungi, viruses and other microorganisms, and a growing body of evidence suggests that these microbes aren't bad for us. In fact, they're vital for our health. NPR's Rob Stein has been exploring the human-microbe symbiosis in a series of stories, and he joins us now to talk about what he's found. Hi, Rob.
ROB STEIN, BYLINE: Hi. Nice to be here.
CHAKRABARTI: Great to have you. So first of all, let's talk about this notion that we are basically covered head to toe, inside and out, in microbes. What's going on there?
STEIN: Yeah. You know, I think like a lot of people, I grew up with this pretty simple idea about things like bacteria, fungi and viruses. It's basically that they're scary things that are swarming out there in the world and they're just waiting for their chance to invade our bodies and make us sick. And up until recently, approached this idea the same way, that, basically, the only good microbe was basically a dead microbe.
CHAKRABARTI: Right, the whole germ theory of disease is based on that.
STEIN: Exactly, exactly. And - but in more recent years, scientists have started to realize that it's not that simple. That, yeah, there are lots of dangerous microbes out there. I mean, the list goes on. There's E. coli and staph and TB and hepatitis, you know, it's a long list. And they, you know, they can make us sick, and they can even kill us. But there's a growing realization that most of the microbes out there, especially those that are in and on our bodies, aren't bad for us. And, in fact, we need them. They're essential for our health and well-being.
CHAKRABARTI: And so, how essential are they? I mean, could we live without them?
STEIN: You know, the growing realization is that, no, we really couldn't live without them, that they provide vital functions for our bodies. And without them, we couldn't survive.
CHAKRABARTI: So, Rob, describe how important they are to us. Tell me more about the symbiosis that you're talking about.
STEIN: Yeah. Well, you know, we've known for a long time that the bacteria in our digestive systems are really important, that we need them to help us digest our food. They actually manufacture certain vitamins that are vital to our survival that we couldn't produce any other way. But scientists have started to realize that, you know, there are so many of them. And they're everywhere in our bodies, all over our bodies, from head to toe, that they must be doing a lot more than that. It's got to be more complicated than that and more nuanced.
CHAKRABARTI: You know, Rob, this is really interesting to me because awhile ago, I had to have a little bit of dental surgery. And after that, my doctor gave me a bunch of antibiotics to take to prevent infection from coming into the place where I had a couple of stitches. He said, take them all but then definitely, you should also take, eat plenty of yogurt as well to sort of recolonize the bacteria that you'd be killing off with the antibiotics. So, I mean, it's interesting that we're, on the one hand, while we're beginning to recognize the importance of the microbiome, we still don't necessarily have drugs that can selectively target what we want. We sort of do a slash and burn across the microbiome when we take some really powerful antibiotics.
STEIN: Oh, there's no question about that. And that's one of the big things that scientists think we're doing that might be messing up our microbiomes, which is overusing antibiotics. Of course, you know, we need to take antibiotics when we're really sick and when we have an infection that, you know, really might be life-threatening.
But we - it's pretty clear that we use antibiotics way, way more than we need to. You know, antibiotics are like neutron bombs for our microbes. They completely disrupt the system. And so one of the things that may be playing a role in our health problems these days is that we're using antibiotics too much and disrupting our microbes and leaving us vulnerable to diseases. And that's just one of several trends in modern society that scientists think may be playing a role in disrupting our microbiomes.
Another one is big increase in C-sections, which means babies don't get exposed to their moms' microbes. Not enough moms breastfeeding, meaning again that the babies don't get exposed to microbes that could be beneficial. There's the overuse of antibiotics that you mentioned and we've been talking about. And all those things together, scientists think may be playing a role in some of the diseases that have been increasing big time in recent years, things like asthma, allergies, autoimmune diseases. And they all may be because our immune systems don't develop properly and aren't tutored by our microbes as they way they should be.
CHAKRABARTI: I've seen in your reporting that even there may be some relationship between our microbiome and diabetes or obesity?
STEIN: Yeah, yeah. That's one of the most fascinating areas that is being studied right now is that the microbes in our gut, that's the biggest, most diverse habitat for our microbes. And the thinking is that those microbes play really important roles in regulating fundamental parts of our metabolisms, including the way we burn fat and store energy, including the regulation of blood sugar in our blood. And there's increasing evidence that when our microbes get disrupted, blood sugar levels rise and people are more prone to obesity.
In fact, there are some really fascinating papers that have come out over the last couple of weeks that showed that when you compare the microbes of obese people to the microbes of lean people, obese people's microbes seem to be much less diverse, meaning they've lost a lot of microbes that they should have, and that might be playing a role in why they are more prone to gaining weight and developing a lot of the health problems associated with obesity.
CHAKRABARTI: I see that doctors are looking into doing something called a microbiome transplant. What is that?
STEIN: Basically it involves removing the microbes from the digestive system and replacing them with somebody else's. And this is being done right now to treat a condition known as Clostridium difficile, or C. diff, which is actually at epidemic levels right now. It's a really nasty gastrointestinal infection that can become life-threatening. And these are people who have repeated bouts of debilitating infections, and they tried repeated courses of antibiotics. Nothing works. Nothing works. So what they've been trying to do is they basically flush out their systems and replace it with the microbes from a donor. And often it's donated by a spouse or another family member. And the results can be quite miraculous. These are people who look like they were on death's door, within hours or days are fine.
CHAKRABARTI: Wow. You know, I imagine that there are a number of listeners hearing this right now who say, well, I'm very proactive about keeping my microbiome healthy. I take probiotics. I mean, does it work?
STEIN: Reality is, is that there's been some research on some of them. But for the most part, we really don't know yet which of these products really work and what they work for and for who. And so it would be really interesting to see in the next few years where this leads.
CHAKRABARTI: You know, Rob, if we could take a step back for just a moment, I still can't get over that there may be 10 times as many microbes as individual cells that I have. It seems kind of amazing. I mean, it almost makes me wonder if we ought to rethink what it means to be human.
STEIN: You know, that's a very interesting point. One of the things this research has sparked is a kind of philosophical discussion about what it means to be human. And some people have started to refer to this idea that we're really a supraorganism. We're a combination of us and them together - our cells, their cells, our genes, their genes - and that we really have to think of ourselves in an entirely new way, that we're not just a separate, single individual but we're part of the world around us in a way that we really hadn't thought of ourselves.
CHAKRABARTI: Well, Rob Stein is a science correspondent and senior editor for NPR. Rob, thank you so much.
STEIN: Oh, thanks for having me.
CHAKRABARTI: There's more in a moment, so stay with us. You're listening to HERE AND NOW. Transcript provided by NPR, Copyright NPR.