So That's Why

Vegetology
  • 5.0 (1)
  • Education
  • Updated Weekly

You've been told to drink eight glasses of water a day. You've chased 10,000 steps like it's some kind of biological law. You've checked your cholesterol without being entirely sure what you're actually checking for. Most health content tells you what to do. Nobody explains why. That's the gap So That's Why was made to fill. Each week, Jen, Chris, and Matt take one everyday health question — the kind that's been nagging at the back of your mind, or that you've just accepted without thinking — and unpack the actual science behind it. Where did this idea come from? What's really happening inside your body? And does the evidence actually hold up? What they find is often surprising. The 10,000-steps rule was invented by a Japanese marketing team in 1964. The eight-glasses-of-water recommendation came from a misread document. The reason some people turn tomato-red when they exercise has nothing to do with fitness — it's about blood vessel density. The thing that makes you cry when you chop onions was only properly understood in 2002. Cholesterol is in every single cell of your body — so why the terrible reputation? The science is real, the research is specific, and the conversations are genuinely fascinating. And the three people having them have the backgrounds to get it right. Jen holds a PhD in biochemistry and molecular biology. She asks the questions you're thinking — informed ones, not naive ones — and keeps the conversation grounded in the human experience of all this biology. Chris is a formulation scientist with over 30 years of experience. He's read the studies, knows the mechanisms, and has the analogies that make complex biology actually click. Matt looks at the science and asks what it means for real people, with real lives, real schedules, and no time for perfectionism. Together they hit that sweet spot between too technical to understand and so simplified it's not actually true anymore. Getting there, it turns out, is harder than it sounds. So That's Why doesn't give you a list of rules to follow. It doesn't shame you for the things you haven't been doing. It explains the mechanism — the actual biology — so you can make decisions that fit your life, rather than just following advice that might not apply to you at all. Episodes run about 20 minutes. They're built for commutes, workouts, or cooking dinner. By the end of each one, you'll be able to explain the answer to someone else — which is the whole point. New episodes every week. Subscribe and find out why.

  1. 4d ago

    Why Do We Need Cortisol?

    Cortisol has become the hormone everyone wants to get rid of. It is also one of the reasons you can get out of bed at all. Jen, Chris and Matt unpack what cortisol is actually doing while you go about your day. They cover how the HPA axis works as a self-correcting chain rather than a tap left running, why cortisol climbs before you wake and jumps again in the first half hour after you open your eyes, and how one hormone reaches nearly every tissue in the body by slipping into the nucleus of your cells and changing which genes are switched on. They also look at where the frightening reputation genuinely comes from. Chronic elevation is a real problem, the cortisol belly has more behind it than you might expect, and a flattened daily rhythm is one of the most consistent biological findings in depression. Adrenal fatigue, on the other hand, is not a recognised diagnosis. In this episode 00:00 Introduction01:13 What cortisol actually is02:49 How your body decides how much you get04:10 The daily rhythm and the cortisol awakening response08:46 When cortisol goes wrong11:09 Adrenal fatigue and the myths the internet loves14:54 What actually helps19:03 Well-timed cortisol, not low cortisol Cortisol Is Talking to Almost Every Cell You Own (01:13)Cortisol is a glucocorticoid, a steroid hormone built from cholesterol by the adrenal glands that sit on top of your kidneys. Nearly every tissue in the body carries glucocorticoid receptors, the docking sites cortisol uses to pass instructions into a cell. The reason its reach is so wide comes down to one property. Cortisol is fat soluble, so it slips straight through the cell membrane and into the nucleus, where it changes which genes are switched on. "So it's not tucked away doing one small job then, it's talking to more or less all of me at the same time." MattThe System Was Built to Turn Itself Down (02:49)The HPA axis is a three-part chain. The hypothalamus releases CRH, which tells the pituitary to release ACTH, which tells the adrenals to release cortisol. Once cortisol rises, it signals back up the chain and tells the top to ease off. "It's not a tap left running. It turns itself down once the messages seem to have landed." MattAlmost everything that goes wrong with cortisol is a version of that tap failing to turn itself down. Cortisol Clocks On Before You Do (04:10)Cortisol runs highest in the early morning and lowest around midnight. On top of that sits the cortisol awakening response, named by the Endocrine Society. In the first half hour after waking, cortisol jumps a further 38 to 75 per cent on top of the level it was already climbing to, in roughly 77 per cent of people. That rise is not a side effect of waking up. It is part of the signal that wakes you, and current thinking is that it is anticipatory. The jump tends to be bigger before a workday and it goes flat in burnout. "So the snooze button then is me arguing with my own biology, and it seems losing." MattAdrenal Fatigue Is Not the Problem to Solve (11:09)Adrenal fatigue, the idea that the glands get exhausted and stop making cortisol, is not a recognised diagnosis and the evidence does not support it. What is real is HPA axis dysregulation, where the signalling between brain and glands drifts out of rhythm. "The glands aren't worn out, the timing's off, and that's a very different thing to put right." ChrisThe team are also clear that a genuine cortisol problem is a blood test and a conversation with a doctor, not a hunch from an internet forum. And on supplements, they are upfront. Vegetology sells them, and for cortisol specifically the evidence is thin. What Actually Helps (14:54)Sleep is the single strongest regulator of the rhythm, by a wide margin. Gentle to moderate movement nudges the baseline down over time, while constant over-training keeps cortisol stuck high. A sharp blood sugar crash is one of the strongest triggers there is for a cortisol spike, so regular meals with a bit of protein help. Easing back on the big afternoon coffee and late alcohol helps the evening dip arrive on time. "You were never meant to have low cortisol, you're meant to have well-timed cortisol." JenAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research. Website: https://www.vegetology.com/so-thats-why-podcast

  2. Sep 3

    Why Do We Get Goosebumps?

    A cold shower, a jump scare and your favourite song all trigger the same reflex. Here's why we get goosebumps, and what they really mean. This week, Jen, Chris and Jamie unpack one of the body's quietest mysteries. Why does a freezing shower, a fright in a dark room and the best moment of a song you love all produce the exact same reaction? The answer starts with a single nervous-system circuit and a tiny muscle at the base of every hair. Along the way, the team explores why goosebumps are far more common than most people assume, the surprising 2020 finding that links the reflex to hair growth, why some people get musical chills and others never do, and a neat myth-bust: most of the goosebumps you think you feel never actually reach your skin. There's a rare superpower, a gentle wellbeing footnote, and Chris's obligatory Captain Sensible moment. In this episode: (01:44) How common goosebumps really are(03:42) The biology behind the bumps(05:52) Where the reflex comes from(08:20) Frisson and why music gives you chills(10:17) Why the shiver and the bump are not the same thing(12:21) What goosebumps say about you Goosebumps Are a Whole-Body Reaction, Not Just Your Hair (03:42)Almost every hair on your body has a tiny muscle at its base called the arrector pili muscle. When it contracts, it tugs the hair upright and pulls the skin into a little dome. Across a whole patch of skin, that gives you the pebbled look named after a plucked goose. The trigger is the sympathetic nervous system, the same side of you that runs fight-or-flight, with noradrenaline carrying the message. For almost everyone, it is completely involuntary. "Picture it less like an alarm and more like an orchestra following the same conductor." (Chris)"Goosebumps are simply the part of the performance that you actually see." (Jen)The Reflex Has a Surprising Second Job (06:55)Goosebumps are not the do-nothing quirk people assume. A 2020 study found that the nerves setting off goosebumps sit right next to the stem cells in your hair follicles. A brief burst of cold gives you the bumps. Prolonged cold can nudge those same nerves into helping the follicle grow new hair. It is still fresh research, but it suggests the reflex is doing quiet maintenance work most of us never knew about. Frisson Explains Why Music Gives You Chills (08:20)The musical version of goosebumps has its own name: frisson. Your emotional brain flags a sudden swell in the music as a possible big event and fires the response. Then the rest of your brain catches up, confirms you are safe, and rewards you with a hit of dopamine. Estimates suggest anywhere from 45% to 85% of people get musical chills, and it turns out to be less about being emotional and more about how actively you engage with what you are hearing. "So it's basically a jump scare with a happy ending." (Jamie)The Shiver and the Bump Are Not the Same Thing (10:17)Here's the myth-bust. When researchers use skin sensors to measure the real muscle response, only about a third of the goosebumps people report actually show up on the skin. The shivery chill you feel and the physical contraction are two separate events. They often travel together, but they don't have to. "So most of the time that I think I've got goosebumps, I haven't actually got goosebumps. It's my brain telling me I've got goosebumps." (Jamie)About So That's WhySo That's Why is a weekly podcast where Jen, Chris and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research. Website: https://www.vegetology.com/so-thats-why-podcast

  3. Aug 27

    Why Do Cells Turn Cancerous?

    Your body will copy three billion letters of DNA today, tens of billions of times over, and get almost every one right. So the real puzzle is not why cells occasionally go wrong. It is why they so rarely do. Jen, Chris and Matt take on one of the biggest questions the show has tackled, and they take it on strictly as biology. This episode is about what physically changes inside a single cell to turn it cancerous. It does not cover causes, risk or anyone's diagnosis, and the hosts say so plainly at the top. What follows is the mechanism, step by step. The three rules a healthy cell lives by, including the one most people never think about. What a mutation actually is, and why inserting or deleting a letter does more damage than swapping one. The two families of genes that decide whether any of it matters. P53, the Guardian of the Genome, faulty in more than half of all cancers. And why a process that creeps along quietly for years can appear to arrive all at once. The takeaway is not the one you might expect going in. Given the sheer number of cell divisions happening every day, cancer is genuinely rare, and it is rare precisely because the body is so good at catching it. Timestamps 00:00 Introduction and a note before we start 01:00 The scale of what the body gets right 02:36 The rules a normal cell lives by 03:46 DNA, mutations and how errors slip through 06:44 Oncogenes, tumour suppressors and the Guardian of the Genome 09:33 How it accelerates and the epigenetics layer 11:34 The hallmarks of cancer 15:41 So that's why Why the Real Puzzle Is How Rarely Cells Go Wrong01:00 Over a lifetime the body performs tens of trillions of cell divisions, each one copying what is effectively a three billion letter instruction manual. Errors do happen. What is remarkable is the amount of proofreading and repair sitting on top of the process, catching them before they ever matter. Chris reframes the whole topic in one line early on. "Cancer isn't one dramatic event. It's what happens on the very rare occasions where a series of those safeguards fail in the same cell one after another." (Chris)Jen also sets out the three rules a healthy cell lives by. It divides only when signalled to, it does its specific job, and it dies on a schedule. That last one is called apoptosis, a controlled self shutdown the body uses to clear out cells that are old, damaged or no longer needed. Matt's response is the one most listeners will share. "So my cells are programmed to die. Sounds a little bit like a fault, not a feature." (Matt)What a Mutation Actually Is03:46 DNA is a long instruction written in a four letter alphabet, and the letters pair up in a fixed way. A with T, C with G. When a cell divides the double helix unzips and each strand is used as a template to rebuild its partner, which makes the pairing rule a built in check. Errors that slip through come in three kinds. A letter substituted, a letter inserted, or a letter deleted. The reason the last two matter more comes down to how the code is read, in three letter blocks that each code for one amino acid. Insert or delete one and every block after it shifts along, which is called a frame shift. "A substitution is a typo in one word, but an insertion or deletion knocks the whole sentence out of step from that point on." (Matt)Most mutations still never amount to anything. They land in stretches of DNA that do not code for anything, or they get repaired within minutes, or the cell triggers apoptosis. The Two Families of Genes That Decide Whether It Matters06:44 Proto-oncogenes normally drive healthy growth, telling cells to divide when there is a real signal. Mutate one and it becomes an oncogene, locked permanently on, so cells divide nonstop with nothing asking them to. Tumour suppressor genes do the opposite job. They hold growth back, repair DNA and call for apoptosis when a cell is too far gone. The most important is P53, nicknamed the Guardian of the Genome, and Chris notes that it is faulty in more than half of all cancers. "So losing P53 doesn't just allow damage, it removes the very thing that would have caught the damage." (Matt)Jen adds the detail that explains why some cancers appear to run in families. You inherit two copies of each tumour suppressor, so both have to be knocked out before the safeguard is gone. That is the two hit rule, first worked out in 1971 by Alfred Knudson. Being born missing one copy changes where the count starts, and as Chris is careful to say, it does not mean anyone's fate is sealed. Why Cancer Can Look Sudden When It Has Been Building for Years09:33 A cancer cell can carry hundreds of mutations, but most are passengers doing nothing. It is the handful of drivers that matter, and it usually takes six or more of them stacking up in the same cell line. Things change pace when some of the genes knocked out are the DNA repair genes themselves. The genome becomes unstable, a state called a mutator phenotype, and a process that crept along quietly can appear to accelerate. "What looks sudden is usually the visible end of a long, quiet process." (Jen)The episode closes on the hallmarks of cancer, including how a cancer cell becomes effectively immortal by switching the enzyme telomerase back on, and how it learns to hide from the immune system using checkpoint signals such as PD-L1. A 2025 study published in Nature found it can go further still, physically passing its own faulty mitochondria into the immune cells sent to destroy it. And then the reassurance, which is where the hosts deliberately land. "Given the sheer number of cell divisions every day, cancer is genuinely rare." (Jen)About So That's WhySo That's Why is a weekly podcast where Jen, Chris and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research. Website: https://www.vegetology.com/so-thats-why-podcast

  4. Aug 20

    Why Does Stress Make Us Ill?

    Stress gets blamed for everything, yet a little of it is genuinely good for you. So why does stress make us ill? In this episode, Jen, Chris and Jamie unpack one of the most misunderstood ideas in health. Stress on its own isn't the problem. The problem is a system that's brilliant in short bursts but never gets switched off. The team walks through the two systems that fire when your brain senses a threat, why chronic stress is now ranked alongside smoking as a heart risk, and how the same chemistry that saves you in a five-minute scramble starts wearing down your heart, immune system, brain, muscles and gut when it runs for months. Along the way there's a kitchen full of guests who never leave, a healthy dose of Captain Sensible, and a clear, evidence-based look at what actually helps. The goal was never a stress-free life. It's an off switch that works as well as the on switch. In this episode: 00:04 When stress is actually on your side01:22 How big is the problem03:48 What stress actually does to your body06:29 Stress, your heart and your immune system09:22 Brain fog, gut knots and the ageing effect12:47 What actually moves the needle17:22 The goal was never a stress-free life The Good Kind of Stress Has a Name(00:04) Not all stress is the enemy. The nerves before a big presentation or the push before a deadline can sharpen you up, and there's even a word for the helpful kind: eustress. The trouble is that most of us aren't living in short bursts anymore. We're living in the chronic version that never lets go. "I spent years blaming stress for everything, bad mood, lost keys, the lot. Now you're telling me it was on my side the whole time?"JamieA survey of more than 145,000 adults across 144 countries found more than one in three had felt significant stress on an ordinary dayThe World Health Organisation counts over a billion people living with a mental health conditionIn the UK, around 964,000 workers were dealing with work-related stress, anxiety or depression across 2024 and 2025, the sharpest single-year jump on record Your Body Reacts Like a Kitchen Before Guests Arrive(03:48) When your brain senses a threat, two systems fire. A fast one floods you with adrenaline, raising your heart rate and blood pressure. A slower one releases cortisol, which keeps your energy topped up by quietly turning down anything non-essential, including digestion, repair and part of your immune system. "You get a text that guests are arriving at the door in five minutes. Everything urgent gets done immediately. The gas goes on, the hob's on full. That's the adrenaline."JamieFor a short scramble, your body is brilliant at this. The problem is the version where the guests never leave, the hob stays on full day after day, and the upkeep never happens. Chronic Stress Wears the Body Down System by System(06:29) Run that emergency chemistry for months instead of minutes, and the damage shows up everywhere. Chronic stress is now treated as an independent risk factor for cardiovascular disease. Heart: A 2023 study found depression and anxiety raised the risk of a major heart event by about 35% and brought warning signs forward by roughly six months. It doesn't hand you a heart attack on the spot; it moves the timeline forwardImmune system: Short bursts sharpen your defences, but sustained cortisol suppresses them, which is why you often fall ill the first day of the holidayBrain, muscles and gut: The hippocampus can shrink under a long soak in cortisol, muscles brace into tension headaches and a tight neck, and digestion drops out, leaving that knotted feeling "Walking into a room and forgetting why you went there isn't you being hopeless. It's just chemistry."JamieWhat Actually Moves the Needle(12:47) The strongest evidence is for movement, and the dose is gentler than most people think. Around 20 minutes of something moderate on most days lowers cortisol and improves sleep. Consistency beats intensity, breathing helps in the moment, sleep and social contact both steady the system, and if stress is genuinely affecting your health, that's a conversation with a doctor rather than a podcast. "The best exercise is one that you will actually do."JamieAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research. Website: https://www.vegetology.com/so-thats-why-podcast

  5. Aug 13

    Why Do We Get Afternoon Energy Crashes?

    Ever wondered why your energy nosedives at almost exactly the same time every afternoon? Surveys put the average moment at a suspiciously precise 2:36 PM. The twist is that it happens whether you eat lunch or not. In this episode, Jen, Chris and Matt unpack the real reason behind the afternoon slump. It isn't one thing breaking down. It's four biological systems reaching their low point at the same time and amplifying each other into a measurable dip in focus, accuracy and motivation. They walk through circadian rhythm, sleep pressure, cortisol and food, explain why some people crash much harder than others, and finish with the small, realistic things that actually move the needle. No burpees required. In this episode: 00:00 The suspiciously precise 2:36 PM crash02:29 The real cost at work04:42 The four biological forces10:20 Why it hits some people harder14:00 What actually helps17:30 Working with your biology, not against it The Afternoon Crash Has Almost Nothing to Do With Lunch (02:29)Most people blame the post-lunch dip on the food itself. The episode busts that assumption early. Lunch can make the dip sharper, but it isn't the cause, because the crash shows up even on days you skip it. The stakes are real and measurable. A report from the American Academy of Sleep Medicine concluded that afternoon cognitive performance drops noticeably, and a Slack survey of over 10,000 desk workers found only one in four people felt productive between 3:00 and 6:00 PM. "So the crash isn't one thing breaking. It's four things showing up at exactly the same time when you don't want it to." — Matt"Cognitive performance drops by about 15 to 25% in the afternoon." — ChrisThe Four Forces That Stack Up (04:42)The dip is really four systems converging. Your circadian rhythm dips twice a day, and the afternoon one drops your core body temperature by around half a degree to a degree. Sleep pressure, driven by a chemical called adenosine, has been building since you woke. Cortisol, one of your main alertness hormones, can be 50 to 70% lower by mid-afternoon than it was in the morning. And food sets the gradient of the slope. The key point is that these forces don't simply add together. They amplify one another, which is why a single afternoon coffee rarely fixes things on its own. "It just decides whether the slope is gentle or steep." — MattCircadian dip: lower temperature, quieter motivation circuits (research from Swinburne University)Sleep pressure: adenosine, the same molecule caffeine blocksCortisol: falls steadily across the day, flattened further by chronic stressFood: a balanced lunch smooths the dip but doesn't remove it Why Some People Crash Harder (10:20)If everyone has these four forces, why does the dip floor some people and barely touch others? Amplifiers. Around 45% of people point to poor sleep as the main reason their crash feels worse, because it lowers your baseline before the dip even starts. Even mild dehydration, a loss of just 1 to 2% of body water, affects attention and fatigue, backed by a meta-analysis of 33 studies. And caffeine, with a half-life of five to seven hours, can still be active at bedtime, quietly shaping tomorrow's slump too. It also varies from person to person. Early risers dip earlier, night owls dip later, and older adults metabolise caffeine more slowly, so the same coffee lingers longer. What Actually Helps (14:00)The fixes are refreshingly ordinary. Drink water early, before you fall behind. Build a balanced lunch with protein, fibre and fats. Get a few minutes of movement and some natural light. And if your day allows, a short nap before 3:00 PM, kept under 30 minutes, can reset things without the grogginess. The things to skip are the big sugary hit and the giant afternoon coffee, both of which borrow energy from later. "It's not a failure, it's a normal rhythm, and the goal isn't to eliminate it, it's to understand it and work with it." — JenAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research.

  6. Aug 6

    Why Do We Get Headaches?

    Your brain has 86 billion neurons and zero pain receptors, so why does a headache feel like it's happening inside your skull? It's one of the strangest facts in human biology, and it changes how you think about every headache you've ever had. In this episode, Jen, Chris, and Matt unpack where head pain actually comes from, why migraines arrive with nausea and light sensitivity, why caffeine both helps and hurts, and why reaching for painkillers too often can quietly make things worse. With over 200 classified types of headache and more than 400 potential migraine triggers, generic advice rarely works. Understanding the mechanism does. By the end, you'll see headaches not as random bad luck but as signals worth paying attention to. In this episode: (00:00) Can your brain feel pain?(01:50) How common headaches really are(03:34) Where head pain actually comes from(05:13) Serotonin, CGRP, and hormones(07:51) Tension, migraine, and cluster headaches(10:07) Triggers, caffeine, and medication overuse(12:34) What actually helps, and when to see a doctor Where Headache Pain Really Comes From (00:03:34)The brain itself can't feel pain, but the structures around it can. The blood vessels, the meninges (the membranes around the brain), and the muscles of the scalp, face, and neck are full of pain receptors called nociceptors. These all feed into the trigeminal nerve, the head's main communication hub, which carries the signal up to the brainstem to be felt as pain. "So the brain isn't actually feeling the pain, it's more like it's being told about the pain from somewhere else." — MattBecause the brainstem also links to systems handling balance, digestion, and light and sound, a bad headache often brings nausea, dizziness, and the urge to shut everything out. That instinct to lie down in a dark room is your nervous system asking for less input. The Chemicals That Turn Headaches Up and Down (00:05:13)A few key chemicals control how loud the pain signal gets: Serotonin affects blood vessels as well as mood. When levels drop, vessels can expand and amplify pain.CGRP (calcitonin gene-related peptide) is released during migraine attacks and dilates blood vessels. It's so central that a whole class of modern migraine drugs is designed to block it.Oestrogen drops before menstruation can trigger migraines, one reason migraines are around three times more common in women than men. In migraine specifically, a process called cortical spreading depression sends a slow wave of altered electrical activity across the brain. It's visible on brain imaging, and it's likely what causes auras. A migraine is a real, measurable biological event, not "just a headache." Tension, Migraine, and Cluster Headaches Explained (00:07:51)The three main types differ in location, severity, duration, and the symptoms they bring: Tension headaches are the most common, affecting around 80% of adults at least once a year (roughly two billion people). They feel like a tight band, are usually mild to moderate, and rarely bring nausea or light sensitivity.Migraines are a neurological condition affecting around 12% of adults. The pain is throbbing and often one-sided, commonly with nausea, light and sound sensitivity, and sometimes aura. They can last from four to 72 hours.Cluster headaches affect about 0.1% of people but are among the most intense pain in medicine. They come in cycles and focus around one eye. Caffeine, Painkillers, and What Actually Helps (00:10:07)Caffeine confuses everyone because it works both ways. Small amounts can help by constricting blood vessels and boosting painkillers, but 400mg or more a day was linked with over a 40% higher prevalence of headache or migraine. Withdrawal can trigger one too. The surprising one is medication overuse. Taking painkillers on more than 10 to 15 days a month can flip the system so the medication itself maintains the headache. The encouraging part is that breaking the cycle often brings real improvement (worth a GP conversation rather than stopping everything overnight). What helps most is reassuringly simple: regular sleep with a fixed wake-up time, steady hydration, regular meals, and stress management. One trial found that drinking about 1.5 litres more water a day improved headaches in almost half of participants. "Headaches are almost a bit like a pressure gauge for everything else going on inside your body." — JenAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research.

  7. Jul 30

    Why Do We Need Iron?

    Iron is the most common nutritional deficiency on the planet, and most of us barely think about it. In this episode, Jen, Chris and Matt unpack why iron quietly runs every cell in your body, why so many of us are running short, and why the tiredness it causes is the kind no amount of coffee will fix. Around a quarter of the world is anaemic, and iron deficiency is behind roughly half of those cases. Yet iron rarely gets the attention of magnesium or vitamin D. The team explains what iron actually does, why a standard blood test can miss a deficiency entirely, the difference between plant and animal iron, who needs far more than the average, and the simple, manageable habits that keep iron levels healthy whatever your diet. In this episode: The most common deficiency you've never heard of (00:48)Iron deficiency without anaemia, and why tests miss it (03:08)What iron actually does in the body (05:12)Heme vs non-heme iron and what affects absorption (08:23)Who needs more iron (11:50)Food sources, testing and supplements (16:45) Iron Is the Oxygen Courier Service Your Body Can't Run WithoutAround 70% of the iron in your body is locked inside two proteins, haemoglobin in your red blood cells and myoglobin in your muscles, and both exist to move oxygen around. Each haemoglobin molecule carries four iron atoms, each grabbing a single oxygen molecule in the lungs and releasing it where it's needed. (05:12) When iron drops, your body makes smaller red blood cells with less haemoglobin, so each one carries less oxygenThe delivery never stops, it just sends half-empty parcelsThat single shortage is why symptoms feel so scattered, from brain fog to breathlessness to brittle nails "Iron's basically the postmaster in the postal system. Without it, the oxygen never gets sorted, never gets delivered, and never makes it to the front door." — MattWhy a Normal Blood Test Can Still Miss Low IronThere's a category called iron deficiency without anaemia, where your stores are depleted and you feel rough, but your haemoglobin hasn't fallen far enough to trigger an anaemia diagnosis. The standard test measures haemoglobin, which is the last thing to fall. (03:08) Ferritin, your iron storage marker, is the true early warning signIt often isn't checked unless a doctor specifically asks for itThis is why persistent fatigue gets blamed on being busy or sleeping badly "The true early warning sign is ferritin, which is your iron storage marker, and unless your doctor specifically asks for it, it often doesn't get checked." — ChrisPlant Iron and Animal Iron Behave Very DifferentlyHeme iron from meat, fish and shellfish absorbs at roughly 15 to 35%, almost regardless of the meal. Non-heme iron from plants, eggs and fortified foods absorbs far lower, from 2 to 20%, and is heavily affected by what's around it. (08:23) Phytates in whole grains, nuts and legumes can cut absorption by over 50%Tea, coffee, calcium and some proteins reduce it furtherVitamin C is a standout enhancer, so a squeeze of lemon or a glass of orange juice genuinely helps Who Actually Needs More IronThis is a nutrient where the average barely means anything. An adult man under 50 needs around 8 milligrams a day, a woman of reproductive age about 18, and a pregnant woman about 27, more than a threefold difference. (11:50) Pregnancy is the most demanding window, with around one gram of iron needed across the whole pregnancyFemale athletes, people on plant-based diets and infants aged six months to two years all carry extra demandFor most people, iron is very manageable with a little awareness "People often describe it as the lights coming back on, because every system that depends on oxygen delivery suddenly has the resources it needs again." — JenAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris, and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research.

  8. Jul 23

    Why Does Alcohol Affect People So Differently?

    In any group, one person is merry after two drinks while another seems untouched all evening. So why does alcohol affect people so differently? It turns out to be one of the most individual pieces of biology there is. In this episode, Jen, Chris and Matt unpack why the same few drinks can land completely differently on two people sitting side by side. They follow alcohol through the liver's two-step, single-lane processing system, explain why more than 500 genetic variants are involved before you've even had a sip, and look at how biological sex, body water, age, food, drink type, medications and mood all stack on top. Along the way they clear up the idea that water cures a hangover, explain why drinks really do hit harder in your 40s, and look at how drinking habits are shifting. No judgment and no rules, just the reasons behind something we've all witnessed. In this episode 02:12 The genetics behind your response03:27 How the liver breaks down alcohol06:51 Sex, body composition and body water08:37 Age, medications and tolerance09:40 Food, drink type and the water myth13:12 Changing drinking trends and lower-risk approaches Over 500 Genetic Variants, Before You've Had a Sip (02:12)The scale of the variation is the first surprise. Researchers have identified over 400 genomic regions and more than 500 genetic variants linked to how people experience and metabolise alcohol. That's an enormous amount of difference set before anyone takes a single sip.It's also why blanket advice fits so badly. Two people can drink the same amount at the same pace and end up with very different blood alcohol levels.Even "I know my limits" is only partly true, because those limits shift with sleep, food, stress, age and medications. "There's over 500 genetic factors influencing how you respond before you've even had a sip. Which is a lot of variation, baked in right from the start." — MattThe Liver's Single-Lane Road (03:27)Most of what happens comes down to how the liver processes alcohol, and it does so in two steps. First, an enzyme called alcohol dehydrogenase (ADH) converts the alcohol into acetaldehyde. Then a second enzyme, aldehyde dehydrogenase (ALDH), turns that acetaldehyde into acetate, which is broken down into water and carbon dioxide. Acetaldehyde is the toxic, carcinogenic in-between product. The headaches and nausea come from this, not the alcohol itself.The genes ADH1B and ALDH2 set how fast each step runs. When one runs fast and the other slow, the toxic middle product builds up.The liver can only clear roughly one standard drink per hour. Anything faster simply backs up. "Acetaldehyde is the nasty part, so it's toxic and carcinogenic, and it's responsible for a lot of the unpleasant effects of drinking." — Jen"It's not that the liver is struggling per se. You've got to think of it more like a single-lane road, with traffic building up behind it." — MattSex, Body Composition and Body Water (06:51)Genetics is the foundation, and biological sex is one of the most consistent layers on top, much of it down to body water. Alcohol is water soluble, so it spreads through the body's water. On average men have more total body water, so the same drink is more diluted.Men also have ADH activity in the stomach lining, breaking down some alcohol before it reaches the bloodstream. Women have far less.Muscle holds more water than fat, so two people of the same weight can respond very differently depending on body composition. "Alcohol is water soluble, so it distributes evenly through the body in its water. And on average, men have more total body water." — ChrisAge, Food, Drink Type and the Water Myth (08:37)Age shifts the whole system, and a few in-the-moment factors change the response too. After 30 we lose roughly 3 to 8% of lean muscle mass per decade, which lowers total body water, while the liver becomes less efficient. That's the real reason drinks hit harder in your 40s than your 20s.Food slows gastric emptying, so a meal with fats and carbs can significantly lower peak blood alcohol levels. Lining your stomach genuinely works.Spirits and carbonated drinks absorb faster than beer or wine. And water helps hydration and comfort, but it doesn't lower blood alcohol or do much for a hangover. "It's a real physiological shift. And that's why people often say drinks hit harder in their 40s than their 20s." — JenAbout So That's WhySo That's Why is a weekly podcast where Jen, Chris and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research.

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About

You've been told to drink eight glasses of water a day. You've chased 10,000 steps like it's some kind of biological law. You've checked your cholesterol without being entirely sure what you're actually checking for. Most health content tells you what to do. Nobody explains why. That's the gap So That's Why was made to fill. Each week, Jen, Chris, and Matt take one everyday health question — the kind that's been nagging at the back of your mind, or that you've just accepted without thinking — and unpack the actual science behind it. Where did this idea come from? What's really happening inside your body? And does the evidence actually hold up? What they find is often surprising. The 10,000-steps rule was invented by a Japanese marketing team in 1964. The eight-glasses-of-water recommendation came from a misread document. The reason some people turn tomato-red when they exercise has nothing to do with fitness — it's about blood vessel density. The thing that makes you cry when you chop onions was only properly understood in 2002. Cholesterol is in every single cell of your body — so why the terrible reputation? The science is real, the research is specific, and the conversations are genuinely fascinating. And the three people having them have the backgrounds to get it right. Jen holds a PhD in biochemistry and molecular biology. She asks the questions you're thinking — informed ones, not naive ones — and keeps the conversation grounded in the human experience of all this biology. Chris is a formulation scientist with over 30 years of experience. He's read the studies, knows the mechanisms, and has the analogies that make complex biology actually click. Matt looks at the science and asks what it means for real people, with real lives, real schedules, and no time for perfectionism. Together they hit that sweet spot between too technical to understand and so simplified it's not actually true anymore. Getting there, it turns out, is harder than it sounds. So That's Why doesn't give you a list of rules to follow. It doesn't shame you for the things you haven't been doing. It explains the mechanism — the actual biology — so you can make decisions that fit your life, rather than just following advice that might not apply to you at all. Episodes run about 20 minutes. They're built for commutes, workouts, or cooking dinner. By the end of each one, you'll be able to explain the answer to someone else — which is the whole point. New episodes every week. Subscribe and find out why.

Information

  • Creator
    Vegetology
  • Years Active
    2026
  • Episodes
    33
  • Rating
    Clean
  • Copyright
    © Copyright 2026 Vegetology
  • Show Website
    So That's Why

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