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Welcome to The Dr Kumar Discovery Podcast, where Dr Kumar challenges conventional medical dogma and offers fresh perspectives on optimizing health and wellness.
Welcome to the doctor Kumar Discovery podcast. My name is doctor Ravi Kumar. I'm a board certified neurosurgeon and assistant professor at UNC. Today, we're gonna talk about the magical biochemistry of Thanksgiving. Thanksgiving is one of those rare days where everything seems to click.
Ravi Kumar MD:Good food, family, football, heavy plates, full bellies, and that deep exhale that only happens once or twice a year. You feel calm, you feel content, and you sleep like a rock. And for as long as most of us can remember, we've heard the same line. Turkey is packed with tryptophan, and tryptophan makes you sleepy. But is that really the whole story?
Ravi Kumar MD:Does that warm, relaxed, almost drowsy Thanksgiving feeling come down to one amino acid hiding in a roasted turkey? If that were true, turkey would basically be a prescription sedative wrapped in gravy. But the truth is more interesting. Tryptophan is part of the picture, but Thanksgiving is actually this perfect collision of biochemistry, nutrition, and behavior. It's a day where what we eat, how we eat, and who we eat with all stack together and push the body into a state of relaxation, safety, and emotional ease.
Ravi Kumar MD:And those words are not just flowery wellness talk. This is real physiology, actual hard science that's been studied for decades. It explains why the specific meal on this specific day with this specific social rhythm pulls us into an almost childlike state of being where we're satisfied and ready for the best sleep of the year. So in this episode, we're gonna crack it wide open. We'll look at what tryptophan actually does, how it turns into serotonin and melatonin, why carbs play an important role, and how the simple act of gathering with the people you love changes your whole nervous system.
Ravi Kumar MD:So before we dive into that, I first wanna say happy Thanksgiving. I hope today brings you warmth, good food, and people you care about. And second, it's important to say that none of what we talk about here should be taken as medical advice. I'm a doctor, but I'm not your doctor. Everything in this episode is for educational and informational purposes only.
Ravi Kumar MD:My goal is to help you understand your own biology a little better. I want you to understand and appreciate the chemistry, the behavior, and the rhythms inside your body and brain that make Thanksgiving so unique. And one last thing, if you're enjoying this show, please take a moment to rate it on Apple Podcasts. It makes a huge difference in helping new listeners find the podcast, and it keeps me putting out good evidence based information because I feel motivated when you guys review me. So please do it if you can, and I'd be super appreciative.
Ravi Kumar MD:Okay. Let's start simple. What is tryptophan? Tryptophan is an amino acid, and amino acids are the building blocks of proteins. And proteins are the molecular machines that make life happen.
Ravi Kumar MD:They form structures, carry signals, move things around, and run the chemistry that basically keeps us alive. And tryptophan is special because it's essential. That means your body can't make it on its own. You have to get it through food. And the brain cares about tryptophan for one major reason.
Ravi Kumar MD:It's the raw material for two chemicals that shape how we feel and how we sleep, serotonin and melatonin. So let's talk about serotonin first. Serotonin gets called the mood chemical, and there's truth to that. In the brain, serotonin helps us remain calm, steady, resilient, and able to handle stress without feeling overwhelmed. It's the molecule that creates balance in our brains and in our bodies.
Ravi Kumar MD:Interestingly, over 90% of serotonin is actually made in the gut. There, serotonin helps control digestion and how the whole system keeps rhythm. It's a key communicator between what you eat and how your body processes it. And another large portion of serotonin sits inside platelets where it helps regulate blood vessel tone, clotting, and wound healing. I like to think of serotonin as the molecule of balance and flow.
Ravi Kumar MD:It helps steady our emotions, keeps digestion moving smoothly, and supports healthy circulation, all working together to keep the body in a stable, responsive state. So the other chemical that comes from tryptophan is melatonin. Most of us know melatonin because it's sold as a sleep supplement, but melatonin doesn't actually knock you out. It's really a timing signal. It's the brain's way of saying, it's nighttime, start winding down.
Ravi Kumar MD:Melatonin helps trigger the onset of sleep and anchors your circadian rhythm, which is the internal clock that tells you when to be awake and when to be asleep. Now here's how the large amounts of Thanksgiving tryptophan fit into this whole picture. Tryptophan is converted into a molecule called five hydroxytryptophan or five HTP by an enzyme called tryptophan hydroxylase. Five HTP then becomes serotonin. Later in the pineal gland, that serotonin is converted into melatonin.
Ravi Kumar MD:The path is simple, tryptophan to five HTP to serotonin to melatonin. During the day, serotonin helps regulate mood and balance the body. Then at night, some of that serotonin is turned into melatonin, which sends the go to sleep signal. Now let's talk about what actually happens when you eat a meal that's rich in tryptophan. Tryptophan can't just float into the brain.
Ravi Kumar MD:It has to cross the blood brain barrier through a specific transporter called the large neutral amino acid transporter, and tryptophan isn't the only one trying to use that doorway. Other amino acids like leucine, isoleucine, valine, and phenylalanine are all competing for the same transport system. They're basically all lining up for the same ride into the brain. So the more of those competing amino acids you have in your bloodstream, the harder it is for tryptophan to get in. If tryptophan makes up a small slice of the total amino acids in circulation, only a small slice of the tryptophan gets into the brain.
Ravi Kumar MD:But if tryptophan makes up a larger share of that pool of amino acids, it has a much better chance of winning space on that transporter. In other words, the brain supply of tryptophan doesn't rely on the absolute amount of tryptophan you ate. It relies on the ratio of tryptophan to the other amino acids in your blood. Now here's the catch with turkey. Turkey doesn't just contain tryptophan.
Ravi Kumar MD:It contains all of those other competing amino acids. So eating turkey by itself doesn't give tryptophan an easy path into the brain. But this is where Thanksgiving gets interesting. On Thanksgiving, you're not just eating turkey, you're eating mashed potatoes, stuffing, rolls, pie, all full of carbohydrates. When you eat carbohydrates, your blood sugar rises, and your body releases insulin.
Ravi Kumar MD:Insulin helps move glucose into cells, but it also pulls many of those competing amino acids into muscle and other tissue more strongly than it pulls on tryptophan. As those other amino acids leave the bloodstream, the ratio shifts. Suddenly, tryptophan makes up a bigger share of what's left in circulation. Now tryptophan finally wins the competition for that transporter and more of it crosses into the brain through the blood brain barrier. And once it's in the brain, your body can make serotonin.
Ravi Kumar MD:Higher serotonin levels are what give you that calm, content, easy feeling after a big Thanksgiving meal. Then as the evening arrives and the light fades, some of that serotonin gets converted into melatonin in the pineal gland, and that's what sets the stage for deep sleep. And all of this stacks with the basic physiology of a huge meal. A large meal pushes the body into rest and digest mode. Blood flow shifts towards the gut, alertness drops, and if you add a glass or two of wine, which acts on GABA receptors slowing down the central nervous system, you've created the perfect recipe for a Thanksgiving slumber.
Ravi Kumar MD:So it's not just the turkey. It's the carbs, the insulin response, the shift in amino acid ratios, the serotonin bump, the nighttime conversion of melatonin, and the rest and digest state, all working together to pull you into that classic Thanksgiving calm. So that's the biochemistry of Thanksgiving, and it's super cool. But here's the truth, tryptophan isn't the whole story. Thanksgiving feels good long before the first bite of turkey ever hits your tongue.
Ravi Kumar MD:Your body and mind start to relax the moment you walk into a room filled with people you trust. Before the carbs, before the serotonin bump, something deeper is already happening. The brain is always asking one quiet question. Am I safe? Most of the time, we don't notice it.
Ravi Kumar MD:We're rushing, pushing, surviving. But when the answer finally feels like, yes, you are safe, the nervous system shifts. The body moves out of defense mode and into repair mode. In that sense of safety, an afternoon with nowhere to be, no deadlines, no traffic, no pressure, no conflict, it's the best medicine all on its own. And a huge part of that feeling of safety comes from connection.
Ravi Kumar MD:You see, human beings were built to live in groups. That's how we survived. We watched out for each other, we fed each other, we raised children together, and that wiring never went away. Strong relationships are powerful. In fact, long term studies show that people with deep, consistent social connections live longer, and people who are isolated have significantly higher risk of early death.
Ravi Kumar MD:The effect size is on par with some of the biggest medical risk factors that we treat every day. But we don't prescribe connection the way we prescribe medications, even though it can completely change your biology. Being with people you love literally buffers stress. It lowers cortisol. It releases oxytocin.
Ravi Kumar MD:It nudges the autonomic nervous system towards calm. The voices, the laughter, the hugs, the stories, these are biochemical signals. They tell the brain you're safe and you belong. And when that message lands, the whole body downshifts. Muscles loosen, breathing eases, the threat system quiets, and that calm sets the stage for gratitude, contentment, and later that night, the best sleep you've had in months.
Ravi Kumar MD:So what you're feeling on Thanksgiving isn't just the turkey. Yes, the tryptophan and the carbs help, but the deeper magic is a sense of belonging. So here's my prescription to you. Spend this Thanksgiving with someone you truly care about. Reach out to someone you've lost touch with.
Ravi Kumar MD:Say the things you're grateful for out loud to yourself and to those around you. And if there's a relationship that needs healing, let this holiday be the opening. Give your brain the permission it's been waiting for that you can actually let go for a little while and let love, social connection, and gratitude heal your wounds. This is how humans heal. Through food, yes.
Ravi Kumar MD:Through chemistry, yes. But even more through human connection. So love, laugh, eat turkey and carbohydrates, and let the biochemistry of Thanksgiving work its magic. So happy Thanksgiving, my friends. I'll see you in the next episode.
Ravi Kumar MD:Cheers.