Clean Gut by Alejandro Junger, M.D.
17 Dec 2025 · 13 min
Dr. Alejandro Junger argues that chronic disease stems from gut problems, not just symptoms. His 21-day Clean Gut reboot eliminates gluten, dairy, caffeine, alcohol, and sugar, then reintroduces foods to find your triggers. The gut produces most of your serotonin and controls far more than digestion.
Chapters
You're listening to Optimize with Bryan Johnson. More wisdom in less time. Hi, this is Brian. Welcome back to Philosopher's Notes TV. Today we've got another great book, Clean Gut by Dr. Alejandro Junger. Clean Gut Subtitle the breakthrough plan for eliminating the root cause of disease and revolutionizing your health. Dr. Junger is a friend. Alejandro, thank you for your work and for your support. Who's also a New York Times best selling author. He wrote Clean and this book, Clean Gut, we featured Clean before. This one is all about, as the title and subtitle suggests, getting to the root cause of our illness. Alejandro makes a compelling case for why the gut is is the source for all the things that we want to eliminate in our lives. He connects it to heart disease, depression, cancer, autoimmune diseases, everything else we're looking to avoid. We've got a philosopher's note. Bunch of my favorite big ideas and five of my favorite ideas here. So let's jump in. The first idea is symptoms versus root causes. Alejandro kicks the book off with a story of him as a kid following his gardener around. And his gardener would look at a given plant and look at the leaves briefly and then tend to the roots and soil. He looked at the soil and the roots to figure out how to create an environment where the tree can flourish. He didn't spend his time on the leaves, he spent his time on the roots. He says, it's almost silly. Imagine if that gardener would look at the leaves and say, oh, well, you know what? The leaves are turning brown. That's a bummer. So let me actually paint them green so they look better. Then he would be treating the symptoms of that tree's issues rather than the root issues. And he says, look, as a medical doctor, I've been trained over decades, and what we've done is we've become more and more specialized where what we're really doing is treating the symptoms and ignoring the root cause. And it's almost like we're painting leaves green when we see them show up. As Browning says, it's even more outrageous than that. At times we're so good at the science of treating symptoms that we can take an unhealthy branch out and put a healthy branch back in and actually act like everything's okay now, ignoring the systemic root causes of what's leading to those leaves being brown. The symptoms. Right. And the whole point of the whole book is we need to quit looking at symptoms and whether it's any range of diseases or issues and start looking at the root cause and the root of it all, he says, is a healthy, clean gut. Symptoms versus root causes. 1 of the ideas in the book as we look at healing our guts is to eliminate. We're going to talk about toxic triggers, right? Removing the things that actually trigger an unhealthy response from our gut. One of those things we want to remove is, is antibiotics. He says some of the most complicated cases that he deals with are with individuals who have had a ton of antibiotics in their lifetime, particularly at a young age. Right. And he talks about the C section generation of antibiotics before they're even brought into the world. Right. And a whole bunch of issues that come with that. But he makes that point, right, that when we use antibiotics, of course they're magical when they can be life saving human. He in fact saved his own life. Double pneumonia was saved via antibiotics. But we use them too much and we don't pay enough attention to the destruction that the antibiotics do to all the friendly bacteria in our gut. Whole nother conversation. For now, we want to focus on the fact that he says that antibiotics are in a lot of the foods we eat, not just the industrialized meat that we eat and all the antibiotics that are given to the cattle in those situations, but also all the food that, that shows up in boxes and jars and tubes and other things that have preservatives in them. He says the food industry calls them preservatives, but we can call them antibiotics because think about it. How could anything that's alive stay fresh in quotes or good enough to eat for years if the shelf life is super long? They had to put in a ton of preservatives to kill the effective life in it so it didn't spoil. And he says there's a correlation here. The more food you eat that has a longer shelf life, the shorter your life is going to be. So think about that the next time you're shopping. When you look at an item that's in a box or a jar or a tube, think about how long that item will last in your pantry. And then realize the longer it's going to last without spoiling, the shorter your life is going to be. If you consume a ton of that, want to be smart about it, eat whole foods minus our toxic triggers, which we're going to talk about in a moment. But I love that phrase. The longer the shelf life, the shorter your life. It's a powerful thing to keep in mind. Third big idea is nutragenomics, which is basically epigenetics of food. Fascinating stuff. We talk about epigenetics all the time. Epigenetics is above the genes, right? It's how we influence our genetic expression, our DNA, by our lifestyle choices. Well, nutrigenomics is the science of studying how our food choices affect our genetic expression. He talks about the fact that things like cancer are really, really complicated, but it is very, very rarely a genetic equals outcome scenario. It's influenced by our choices bite by bite by bite and movement by movement by movement. As we talked about in Move youe DNA with Katie Bowman, and getting a good night of sleep, after a good night of sleep, after a good night of sleep, taking time for meditation, one minute here, one minute there. All these things influence our genetic expression. We know this unequivocally, scientifically. We're flipping on healthy expression, flipping off unhealthy expression, or not, depending on our lifestyle choices. So keep that in mind, bite by bite. Fourth big idea is gluten. Gluten is our number one toxic trigger. The clean gut program is basically a 21 day reboot where you remove your toxic triggers. The number one thing we want to remove is gluten. Alejandro talks about the fact that gluten is tied to so many different diseases. David Perlmutter calls it kind of a silent poison. It's ubiquitous. It's in obvious things like wheat and rye and barley. But the word gluten comes from the Latin word glue in. And gluten is really, really helpful for food manufacturers to do a ton of crazy things to food. And you find it in everything from hot dogs to ice cream. It's ubiquitous. It should be being removed from our diets because we know that it's connected to so many issues. Instead, it's becoming more and more ubiquitous. One of the key ways to avoid gluten is to avoid processed foods. Again, Alejandro talks about how to approach this. But for now, we want to know that you, if you or your family has some health issues and your health is suboptimal, think about experimenting with removing gluten and seeing if you experience some positive benefits. Which leads us to the fifth big idea, our toxic triggers. This is step one in the Clean Gut program. You need to remove the things that are triggering your unhealthy response in your gut. The key list of things we want to remove include, start with gluten and dairy. Those are our top two most common toxic triggers. Now, some people can deal with gluten and with dairy. A lot of people cannot. I am in the group that cannot. I'm also in the group that Had a ton of antibiotics from the time I was tiny. Right. Restoring healthy gut is unbelievably important for us. So you want to check in and remove those things during this 21 day period of time. You also want to remove caffeine, you want to remove alcohol, you want to remove sugar. Those are our top five toxic triggers. There are other things like corn and soy that you may or may not be sensitive to, but on this program, you take them out, right? And then after the 21 days, you systematically reintroduce different things and see, is this a trigger for me or not? And he says just simply identifying whether or not gluten or dairy or these other triggers are in fact potential triggers, are in fact triggers for you is huge. We want to make the connection between the little choices we're making and how we feel. That is Emerson. Alexander and I talk to Emerson about this all the time. Making the connection, right? When you eat this, then this happens. He really doesn't like having a runny nose. We can make a connection when you eat this type of food. That's the connection, right? That's a toxic trigger. Therefore, let's be more consistent about removing these certain things. So we want to identify our toxic triggers and then go from there. At the end of the book, they talk about the seven guiding principles for clean living. The first rule is removing the stuff that doesn't work. Then you add the things that do work. They say the simple formula is whole foods. Things that occur in nature on their own, naturally, in a whole foods context, Right? One ingredient that you can name. No crazy ingredients, no food that your great grandparents didn't eat, or whole foods minus your toxic triggers. That's a really simple look at the basic underlying plan of an effective nutrition strategy. I'm excited. We're going to be talking a lot more about nutrition in the next few weeks as I Prepare for Nutrition 101. But for now, toxic triggers. Eliminate them, then reintroduce to see what works and what doesn't. Gluten. It's amazing how much stuff is tied to gluten issues. Nutrigenomics, the study of how nutrition affects our genetic expression. The. The longer the shelf life of the food you're eating, the shorter your life. And then symptoms versus root causes. One of the things we didn't talk about is the fact that your gut is also your second brain. I'm always blown away by the fact that 90% of your serotonin is produced in your gut. Alejandro talks about the fact that when he was at the peak of his medical career as a cardiologist working crazy hours, eating horrible food. He was diagnosed with depression, with irritable bowel syndrome, and some other things. He was on a number of prescription drugs and when he saw his psychiatrist, his psychiatrist said, you know what? Your head. And he points to his head, your head is not producing enough serotonin. Your brain is not producing enough serotonin. Alejandro says in hindsight, he should have been pointing at his gut and said, your gut is not producing enough serotonin. Your second brain There are more neurons in your gut than in your brain. Crazy hard to believe, but it's true. We want to have a clean gut and optimize our emotional well being, our physical well being, and everything in between. Hope you enjoyed what was the big idea that jumped out. Think about it, reflect on it, and make it a more integrated part of your life. Here's to a clean gut as we optimize and actualize. Thank you Alejandro. See ya. Hi, this is Brian. I hope you enjoyed that Philosopher's Notes TV episode. If so, I think you'll enjoy everything else we offer at BrianJohnson me two basic things one our free newsletter. It's called the Optimizer. Over 50,000 people start their day with it and they tell us it's pretty awesome. 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