Show Me the Science with Luke O'Neill

Cholesterol has a reputation problem. We tend to think of it as the enemy, but your body makes it for a reason. Every cell membrane relies on it, and it’s the building block for key hormones like oestrogen, progesterone, and corticosteroids. You also get cholesterol from your diet. The real issue isn’t cholesterol itself — it’s where it ends up.
In the early 1900s, pathologists examining people who died from heart attacks found arteries lined with cholesterol-rich plaques, complete with visible crystals. By the 1950s and 60s, research confirmed that high cholesterol in the blood is a major risk factor for heart disease. When plaques build up, they trigger inflammation and clotting, potentially cutting off blood supply to the heart.
Cholesterol doesn’t travel freely in the bloodstream — it’s packaged into tiny particles called lipoproteins. These act like delivery vehicles, carrying cholesterol around the body. Drugs such as statins reduce cholesterol production and improve its clearance, saving millions of lives. Exercise, diet, and blood pressure control are also critical, especially since high blood pressure and high cholesterol together significantly increase risk.
But there’s more to the story. Around one in 250 people have inherited conditions that leave them with very high cholesterol levels. And as listener Tara asked in her email to the podcast, what about Lipoprotein little a — or Lp(a)?
Lp(a) is a specialised lipoprotein that can increase inflammation and clot formation. Elevated levels are linked to a greater risk of heart attack — even if your standard cholesterol numbers look normal. That means measuring total cholesterol alone may not tell the full story.
On this week’s podcast Professor Luke O’Neill explores why cholesterol is essential, how it becomes dangerous, and why particles like Lp(a) could be key to identifying hidden heart risk.
Have a science question you’d like answered? Email [email protected] and it might feature in a future episode.

Why do we sweat? And what secrets does it hold about our bodies? On this week’s podcast, Professor Luke O'Neill dives into the fascinating science of sweat. From keeping our body temperature in check to signalling stress and even potential mate selection, sweat is far more than just water and salt.
The podcast explores how sweat is made by specialized eccrine glands, originating from plasma in our blood, and why humans are among the sweatiest animals on the planet. Luke explains how the average adult can produce up to four litres a day, and why staying hydrated is crucial.
But there’s more: stress, exercise, and climate all change how and why we sweat. Sweat itself is odorless, but bacteria, lactic acid, and urea can create the smells we associate with adolescence, gyms, and armpits. And surprisingly, sweat contains proteins that fight bacteria, hinting at a role in our body’s natural defence.
Could sweat one day be a diagnostic tool for disease? Why do identical twins sweat the same amount? And could it even act as a pheromone signal? Professor O’Neill explains all this and more, in a conversation sparked by a listener question from Siún.
If you want to ask Luke your own science question, email him at:
📧 [email protected]

Weather forecasts are famously imperfect, but the science behind them is far cleverer than we usually give it credit for.
In this week's podcast, Professor Luke O’Neill explores how weather forecasting works, and why floods remain one of the hardest things to predict. Luke isn’t a meteorologist — although he did briefly consider it in college — but too much physics put him off. Still, he’s an ideal guide to the basics because the weather is really about a few core ideas behaving badly.
At its heart, forecasting comes down to temperature, air pressure, humidity, sunlight, and the way air flows like a fluid. Air moves from high to low pressure, dragging wind and weather systems with it. Add water vapour into the mix and things get interesting very quickly.
People have been trying to predict the weather for hundreds of years, using almanacs, folklore, and observation. It was never perfect, but it mattered hugely to farmers and sailors. Rain, in particular, remains tricky. Moist air rises, cools and condenses into clouds — but rain doesn’t just appear. It needs tiny particles like dust, sea salt, or pollen to form droplets, and those microscopic details are hard to pin down.
Today’s forecasts rely on satellites, radar, weather balloons, and ground stations, all feeding data into powerful computer models. Those models keep improving, and artificial intelligence is now helping to sharpen predictions.
Flooding is even more complicated. It’s not just about how much rain falls, but how fast it falls, how long it lasts, and where it lands. Soil type, vegetation, evaporation, and urban concrete all matter. Forests and wetlands act like sponges, while cities can make flooding worse — something Ireland knows well after decades of building on flood plains.
Some countries lead the world in flood modelling, but nowhere reliably predicts flash floods. Luke argues that weather is a brilliant way to teach science, and that we already know how to reduce flood risk. The challenge now is acting on that knowledge and getting on with it.

Why does the marathon push the human body to its absolute limits? And why do some people seem built to keep going when everyone else hits the wall? On this week’s podcast, Professor Luke O’Neill takes a biochemical deep dive into marathon running, sparked by a listener’s request. The modern marathon may trace its roots back to Ancient Greece, but what happens inside the body during those 26.2 miles is a very modern scientific story — one that turns runners into walking, sweating demonstrations of bioenergetics.
Luke explains how the body powers long-distance running by converting energy rather than creating it, moving between carbohydrates and fats to keep muscles firing. ATP — the energy currency of life — sits at the heart of the process, with phosphocreatine, glycolysis and oxygen all playing starring roles. When carbohydrate stores finally run dry, runners hit the infamous “wall”, a moment when the body is forced to switch fuel sources, and everything suddenly feels much harder.
The podcast also looks at how training physically reshapes marathon runners over time: denser networks of capillaries in muscles, powerful hearts with remarkably low resting heart rates, and lungs capable of shifting huge volumes of oxygen. Luke explores why elite runners can seemingly run a marathon at will.
There’s science behind the mental side too. Endorphins and the so-called “runners high” can lift mood for days, while visualisation plays a key role in endurance. Luke even dips into the Guinness Book of World Records to uncover astonishing marathon facts, including runners in their 90s and some jaw-dropping physiological extremes.
Along the way, Luke admits he’s never run a marathon himself — but from a biochemist’s point of view, few sports are more revealing of how the human body really works.
You can suggest future topics by emailing Luke at [email protected].

Turmeric is everywhere – in teas, capsules, curry powders and health ads – but what does it actually do? On this week's podcast, Professor Luke O’Neill explores the science behind the golden root, explaining why it’s been used for centuries in Eastern medicine and what modern research tells us about its effects.
We dive into curcumin, turmeric’s active ingredient, and learn how it fights inflammation, works as an antioxidant, and even interacts with our gut bacteria to become more potent. Luke separates the science from the hype, highlights the evidence for conditions like ulcerative colitis, and explains why taking turmeric might help – as long as it’s not replacing your prescribed medication.
Along the way, we uncover fascinating trivia: the plant’s own sunscreen, why it stains everything yellow, and how it became a sacred dye for Buddhist and Hindu robes. Whether you love it in your curry or in your supplement cabinet, this episode shows why turmeric has earned its golden reputation.