Podcast: How Does Alcohol Impact the Gut Microbiome?

Dr. Stephanie Rutledge: Alcohol has some inherent toxins within it that cause increased intestinal inflammation and allow some toxins that are produced by the bacteria in the gut to escape out of the gut and into the bloodstream.

Courtney: Welcome to Health Matters, your weekly dose of the latest in health and wellness from NewYork-Presbyterian. I’m Courtney Allison.

Have you ever wondered what happens inside your body when you drink alcohol? You may know that excessive drinking can damage your liver, but it can also change your gut microbiome.

To learn more about alcohol’s impact on the gut microbiome, I spoke with Dr. Stephanie Rutledge, gastroenterologist and transplant hepatologist with NewYork-Presbyterian and Weill Cornell Medicine.

She explained how an unhealthy microbiome can lead to a leaky gut and even liver disease. She also offered ways to help foster a more diverse microbiome. These range from simple steps like including more fiber in your diet, to incredible treatments for improving gut health, like fecal transplants.

Courtney: Hi, Dr. Rutledge, thank you so much for being here today!

Dr. Stephanie Rutledge: Thanks so much, Courtney. It’s my pleasure and I appreciate the invitation.

Courtney: So let’s get started with the basics. What is the gut microbiome?

Dr. Stephanie Rutledge: Sure. So the gut microbiome is all of the microbes or the bacteria, viruses, and fungi that inhabit and that live in our Intestines. All the way from the gut to the anus is inhabited by trillions of bacteria that are affected by what we eat and affect how we feel and have very complex interactions with our brain and a lot of our bodily functions.

We know that a microbiome that is more diverse tends to be a healthier microbiome. And that means that people with more diverse microbiomes may feel overall better than those who have a less diverse or a more dysfunctional microbiome.

Courtney: Could I ask you to drill down on what it means to have a diverse microbiome?

Dr. Stephanie Rutledge: Sure, so, I think the microbiome is one of the most exciting areas in medicine because there’s so much that we have left to find out about it. It wasn’t until recently that we could accurately identify the bacteria that are living in our gut. And so for a long time, it was a black box, but now we are starting to understand more and more.

So more diverse a microbiome simply means that there’s a bigger variety of species living in our gut. And so generally we know that the more diverse is usually thought to be better but there are so-called good and bad bacteria that are known to have associations with either more gut health or more gut problems.

Courtney: How is the microbiome influenced by what we eat and drink?

Dr. Stephanie Rutledge: Usually someone’s microbiome is set by early childhood, but as you grow older, it is still possible for there to be minor shifts in the microbiome, depending on what we eat.

So for example, fiber is a prebiotic and that helps to form some of the good or the healthier bacteria within the gut, whereas we know that things like alcohol can have a bad impact on our gut microbiome, making it less diverse and allowing those so-called bad bacteria to proliferate. If someone eats a lot of processed food and not a lot of fiber, their microbiome becomes set a certain way. But if someone changes their diet and increases their fiber, decreases their processed food, it is possible even in the space of a few days to make some really good and impactful changes to your own microbiome that can improve how you feel.

On the other hand, taking things like antibiotics tends to eradicate some of those so-called good bacteria, and it may allow some of the bad bacteria to proliferate. Obviously, antibiotics are essential in some cases, and they can be life saving, but these are just some of the impacts that we know of, that are what we eat and drink and what we ingest, and how it can affect microbiome.

Courtney: What about alcohol? How does that affect our microbiome?

Dr. Stephanie Rutledge: Alcohol’s effect on the microbiome is incredibly interesting. Occasional alcohol is unlikely to affect the microbiome significantly. So if you have someone who doesn’t drink much alcohol, they might have the microbiome that is thought to be most associated with the healthy state.

But when someone starts to drink more than one drink a day for women or two for men, which is the current recommended amount, we start to see change in their microbiome. It becomes less diverse and we see some of the bad bacteria proliferate.

Those who drink to excess and have liver disease may have the worst microbiome of all. And so those with the least diverse microbiome tend to have more severe liver disease, and it’s not just bacteria, but even fungi have been shown to be associated with worse hepatitis and worse cirrhosis in people who drink alcohol.

We’ve seen that this diversity can be improved with reducing or stopping alcohol, but we know that in people with liver disease, the severity of liver disease seems to correlate with the microbiome.

Courtney: Are you able to break down what it is about alcohol that’s affecting the microbiome so much?

Dr. Stephanie Rutledge: It seems like alcohol has some inherent toxins within it that cause increased intestinal inflammation. We see that the lining of the gut becomes looser or more permeable. These tight junctions that are supposed to keep our gut intact start to become a little looser and allow some toxins that are produced by the bacteria in the gut to escape out of the gut and into the bloodstream where they can accelerate liver disease and cause more significant infections and bacterial consequences.

People who drink alcohol are more likely to have a condition called SIBO or small intestinal bacterial overgrowth. As the name suggests, a condition where the bacteria proliferate in the small intestine.

Courtney: Do you know how quickly you can see the impact of alcohol on the gut microbiome?

Dr. Stephanie Rutledge: Alcohol has a very fast effect. As soon as the alcohol hits the gut and the microbiome starts to work on it and break it down. Especially if drinking on an empty stomach, of drinking quickly, a large number of drinks or binge drinking. You can certainly see effects immediately in the gut because the alcohol is being broken down into its byproducts and they’re being absorbed. The microbiome is already starting to ingest the toxins.

Courtney: Okay, and so conversely, if a heavy drinker quits, how quickly can you see gut microbiome recovery?

Dr. Stephanie Rutledge: Within a few weeks, I think you would start to see some meaningful improvement in the diversity of the gut microbiome. We see the same for the liver within four to six weeks, if you are someone who is a heavy drinker. 90 percent of people who drink more than say four or five drinks a day will develop fatty liver or steatosis in their liver. But after four to six weeks in most people, that’s completely reversible.

You would probably have reversed the fat in your liver and probably have completely replenished your microbiome with a brand new healthy set of bacteria, especially if that change in alcohol was accompanied by some more good health habits like eating more fiber, less processed foods, more fruit and vegetables, and a diet that is diverse and includes lots of different food groups and different nutrients.

Courtney: I find that so encouraging to hear, knowing just within a few weeks of cutting back and better habits. That’s really great to hear.

Dr. Stephanie Rutledge: It’s really encouraging. I try to tell that to my patients that there are so many benefits from either stopping or cutting down on alcohol, depending on how severe their liver disease is. But we can see improvements in things like heartburn, which is inflammation of the esophagus or the food pipe. We can see things like improvement in stomach inflammation.

So I think there’s hope out there and it’s never too late. Even in people with more advanced liver disease, we can still see a huge improvement with abstinence from alcohol.

So I totally understand. And it’s nice to go out and have a drink with friends, but just to remember that it doesn’t have to be five or six, maybe it can be one or two.

Courtney: What are some other ways that alcohol impacts our gut?

Dr. Stephanie Rutledge: Alcohol has many, many effects on the gut. It has so many health impacts, not just the microbiome but the risk of cancer, it affects sleep, it can cause cognitive impairment over many years and it can cause, in some people, diarrhea or constipation. It can cause bloating, which can be due to the condition of small intestinal bacterial overgrowth. It can cause more heartburn, and alcohol is one of the most common culprits for causing acid reflux. There are others, but alcohol is one of the easiest ones to address because by drinking less you can decrease the amount of acid that is going back up into the esophagus and improve the symptoms.

So sometimes patients who cut back on alcohol actually tell me that they feel a lot better for a variety of reasons. Their bowel habits might have normalized. Their heartburn has improved. Alcohol is a huge source of empty calories. And so depending on what you’re drinking, it can be full of those empty calories that don’t have nutritional value, but just add huge numbers of calories to our daily intake, which often exceeds the recommended number of calories per day.

Courtney:  So it seems like the gut microbiome affects kind of our entire body, our mind, everything. And since we’re talking specifically about alcohol, is there a connection between a healthy gut microbiome and the liver functioning well?

Dr. Stephanie Rutledge: For sure. We see that the liver likes a diverse, healthy microbiome and that even when you have mice who are fed alcohol, if you give them the microbiome from a person with liver disease, their liver gets worse compared to if you give these alcohol-fed mice the microbiome from a healthy person.

They don’t see the same effect, the same severity of liver disease. And so the microbiome certainly is intrinsically linked with liver disease. We see that the worse the microbiome, the worse the liver disease. And we don’t know exactly whether this is causation or correlation, that the more sick your liver becomes, maybe your microbiome can’t be healthy because of the sick liver, or is it that the change in the microbiome is driving the liver disease?

We see that if you have a less diverse and a more so-called unhealthy microbiome, we see higher rates of inflammation, more intestinal permeability, and more accelerated liver disease. And so I think this is just the tip of the iceberg. We have so much more to learn about the liver and the microbiome, which is why it’s been studied extensively across the country and the world.

Courtney: So when the microbiome is really out of whack, what are some treatments that can really help?

Dr. Stephanie Rutledge: I wish I could say if you take this, this one thing, it’ll fix your microbiome. Drinking less is probably going to help and eating more fiber is probably going to help, too. Then things like having a high protein, low carbohydrate diet. Sort of the general advice that people get from their doctors.

One of the most exciting parts of the microbiome and alcohol is that if you give someone a brand new microbiome, it seems like you can reverse some of the damage that has been done to the liver.The most drastic of these is a fecal transplant, which is when healthy stool from a donor is given either via a capsule or via colonoscopy into someone with liver disease. So I’ve done colonoscopies where you go to the end and you squirt in all of this healthy stool, and we have seen in these very small experimental studies of only a handful of patients, they saw improved survival in people with alcohol associated hepatitis who had a fecal transplant.

Courtney: That’s so interesting. So how does someone’s health improve when their microbiome gets healthier?

Dr. Stephanie Rutledge: So I think there’s a multitude of ways both physical and psychological or mental health can also improve.

We see that the liver likes a diverse, healthy microbiome. And I hope that in the future we would have targeted microbiome treatments for people with liver disease because the microbiome, while it, there may be consequences of giving someone a new microbiome, it can also be a lot safer than the medications that we have to treat liver disease.

The microbiome is really like the depths of the ocean where there are millions of bacteria that have yet to be discovered and we know so little about them. But I think that it’ll be a key part of not just liver health but overall health, will be someone’s microbiome and how we can change the microbiome to restore a healthier state.

We’ve seen that in people with alcohol use disorder changes in the gut microbiome go hand in hand with symptoms like anxiety and depression. And so people, when they drink alcohol, may find that they feel less anxious or they may feel euphoric or less depressed while they’re drinking or while they have the alcohol on board, but the next day their psychologic symptoms may be a lot worse.

Courtney: Yeah.

Dr. Stephanie Rutledge: And so we see that by decreasing the amount that you drink the microbiome can improve, which can in turn improve mental health and psychologic symptoms.

Courtney: You know, we often talk about the link between our physical health and mental health, and to hear about the role the microbiome plays in the gut-brain connection is just so fascinating. Thank you so much for sharing these insights with us today.

Dr. Stephanie Rutledge: Thanks so much for having me, I’m delighted.

 Courtney: Our many thanks to Dr. Stephanie Rutledge. I’m Courtney Allison.  

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