Welcome to Nutrition Bites. The no nonsense podcast where you get the truth about food so you can eat what you want and be healthy. I’m your host Maggie and welcome to the series! Chili peppers are a globally divisive ingredient - you either hate ‘em or love ‘em. But apart from a temporary state of euphoric pain, do they affect our health in any other way? On the menu today, spicy foods.
Growing up I had a general aversion to anything flavored - be it sour, savory or especially spicy. No joke, for a good portion of my youth black pepper was as hot as my palate could handle. Fortunately for both my culinary and social reputation, I’ve become a lot more interesting at meal time, and now I choose to embrace the heat. Well, a little heat at least. Whether it’s cooking with gochujang, drizzling Mexican hot sauce on my eggs, or ordering, wait for it, medium spice chicken wings, I’ve come a long way from my humble, bland beginnings. Now my old aversion to spicy foods is not uncommon, and I think many would agree that avoiding the spice life originates from the same mindset - why do you want to be in pain when you eat? Well for devotees the answer is simple: the addition brings about a whole new experience, and flavor to food. But there’s also another reason often mentioned in the cayenne community - it’s good for you! Folklore has it that eating spicy food can cure colds, boost your metabolism and even induce birth when a woman is past her due date. And while some of these are simply urban legends, the health allure around spice is not entirely false. Which brings us to today’s question: can spicy food improve our health? Let’s dig in.
The hot, fiery, burning sensation of spicy foods is thanks to a family of compounds called capsaicinoids, the most common of which is capsaicin. Contrary to popular belief these molecules are not found in the seeds of chili peppers, rather, the white fleshy pith. And their concentration is what determines whether a pepper will provoke a funky little tongue tingle or a scorching from the depth’s of hell, out of body experience. This range of heat is measured through something called the Scoville scale, with the concentration of capsaicinoids in a pepper corresponding to a number of Scoville Heat Units. The higher that number, the more mind-numbing the spice is. Ranking at the very bottom of the Scoville scale, is the bell pepper - with 0 Scoville Heat Units to its name. Close by is one of the lesser scary peppers - the jalapeno. It has a heat range of 2500 - 10,000 Scoville Heat Units. And jumping all the way to the top of the scale is the world’s hottest pepper, the Carolina Reaper. This monstrosity is at least 1.5 million Scoville Heat Units, or, around 150x hotter than a jalapeno. Now for any of you mildly curious about what it feels like to meet the Reaper, first off don’t. And secondly, go watch any youtube video titled “Carolina Reaper challenge” to witness the absolute torment that will ensue should you choose to pursue your curiosity. Now eating this scorching pepper may not kill you, but it will give you the worst bathroom trip of your life. So what exactly happens to cause such temporary torture?
The uncomfortable sensations which occur when we eat spicy food is thanks to capsaicin interacting with a cellular receptor called TRPV1. Now TRPV1 helps regulate body temperature, but it also can cause us to perceive pain - even if no actual damage has occurred. So when capsaicin comes into contact with TRPV1 two things happen: an internal warMing of the body, and a triggering of pain. Now these receptors are found all over, from the inside of the mouth, to the outside of the skin, within the joints, and across the gastrointestinal and respiratory tracts. This is why the effects of eating spicy foods can be felt throughout the body. For example, over activation of TRPV1 in the diaphragm can trigger hiccups and in the stomach lining can lead to nausea and even vomiting. At their core capsaicinoids are chemical irritants, so even just exposing our bare skin to high concentrations, like when cutting a load of jalapenos for salsa season, can feel like we’ve been physically burned. Now despite the biological branding of being a known pain-inducer, humans willingly, and regularly, consume chili peppers. Whether it’s in dried or fresh form, capsaicin is a key component of so many cuisines. And part of their ancient allure has been their supposed health benefits - like the Traditional Chinese Medicine belief that chili raises the yang energy in the body to improve circulation. But modern day science has its eye on capsaicin for different reasons.
One of spicy foods most well studied and popular health claims is that it can speed up your metabolism. It’s one of the reasons why cayenne pepper is included in the Master Cleanse - a 10 day juice fast once popular with celebrities when they wanted to drop weight. This water, lemon, maple syrup and cayenne pepper concoction allegedly “tones, cleanses and heals the body”, but critics, of which there are many, are quick to call this a buzzword-laden starvation diet. So don’t bother trying it.
Now as I detailed in Episode 22 of the podcast, by and large your metabolism can’t change..at least not permanently and rarely to a big degree. However, that doesn’t make capsaicin’s metabolism boosting claim completely false. Metabolism covers a wide range of biological processes all centered around transforming energy from food into energy our body can use. Having a quote unqote “high” metabolism, or more specifically metabolic rate, simply means your body has a large caloric need - it uses a lot of energy and so requires a high number of calories to survive. To many people, a high metabolic rate is enticing because it means that at rest, your body uses, or “burns” a lot of calories. And this is like catnip to folks engaged in fitness, or who want to lose weight. Spending energy during nothing, means a higher likelihood of maintaining photoshop worthy abs without having to extend the gym sesh.
Now one of the ways to “raise” your metabolism is through a process called thermogenesis. Thermogenesis is simply the use of energy, or calories, to produce heat. And you know what raises your internal temperature real nice? Spice. Dozens of clinical trials have concluded that capsaicin has a thermogenic effect. Triggering the TRPV1 receptor causes your body to produce heat - which is part of the reason why people sweat during and after a spicy meal. But that’s not all. Clinical trials have also shown that capsaicin affects our metabolism in another way - by shifting our body’s preferred energy source. You may recall that carbohydrates are the #1 fuel choice when we need energy. However, studies have shown that consuming capsaicin changes this - instead temporarily directing the body to use fat to meet our energy needs.
Summing up these two metabolic effects of capsaicin, many fitness influencers and Buzzfeed authors would be quick to proclaim that “Sriracha boosts metabolism and burns fat”, but the actual magnitude of this effect is far less exciting. On average, scientists estimate that ingestion of capsaicin can increase energy expenditure by 50 calories a day. In other words, spicy foods will help you burn the caloric equivalent of a single oreo. Theoretically this could result in weight loss, but only after one or two years. So it’s not as if this “ramped up metabolism” is really all that effective. And when you measure the effects of spicy food consumption on weight loss, fat loss, and obesity on a populational scale, there’s no consistent proof that anything changes. In short, despite all the internet hype about the metabolic boosting effects of cayenne pepper, capsaicin doesn’t actually affect your weight in any meaningful way.
But where it may have more of an impact on your health is far more interesting - helping you live longer. In 2015 a landmark observational study on 500,000 Chinese adults found that compared to people who rarely ate spicy food, those who consumed it every day had a 14% lower risk of premature death. In this study premature death included dying from cancer, heart disease, and respiratory disease. These results were further strengthened in 2019 when a study on 22,000 Italian adults found that those who ate chili peppers four times a week had a lower risk of death versus those who avoided the heat completely. And finally, a meta-analysis from last year which covered additional studies in the US and Iran concluded that regularly eating spicy food can reduce your risk of early death by around 12%. Now it’s unclear how or why this result is seen, but it’s definitely a bonus for those who already eat spicy food. So does this mean that those who aren’t daily capsaicin consumers should start learning to live with the heat? Well, not exactly.
Studying a single molecule like capsaicin in the context of long-term health is very difficult, and the research done so far is brimming with limitations. One key variable is the quantity of capsaicin needed to see a health effect. In clinical trials studying capsaicin, the dose is often quite big and given in supplement form. In one such study, subjects ingested a 6 milligram capsaicin pill - which is the equivalent of eating 6 dried jalapenos in one sitting. Not a regular snack for the average Joe I take it. And in real life people cook with a wide variety of capsaicin. Including different types of chili peppers, volume, and formats - like hot sauce, fresh peppers, dried peppers and spice blends. The diversity of our spice life makes evaluating the quantity of capsaicin consumed IRL really hard, and applying scientific findings that much more difficult.
Now when it comes to evaluating the strength of capsaicin research from observational studies, we all know by now that this data can only suggest correlation not causation. And because this science typically relies on people’s memories of their daily food intake and subjective interpretation of spiciness, the results are not always accurate. Finally, the biggest limitation to studying the health effects of capsaicin on a populational scale is the fact that we don’t eat this molecule on its own! This reality makes it impossible to isolate the effects of capsaicin compared to every other substance in a meal - especially over a lifetime. Multiple researchers even hypothesize that the longevity effect of capsaicin may be due to reduced salt intake, not increased spice consumption. It’s been shown that people often use chili peppers as a seasoning in place of sodium, thereby reducing their intake of the latter nutrient which we tend to overconsume. A separate, but related, example is noted by the author of the Italian longevity study. They state that in Mediterranean countries fresh chili is commonly eaten alongside legumes and vegetables. So it could actually be the presence of fibre and plant protein in these traditionally spicy meals, rather than capsaicin, that is contributing to their death-defying finding.
Now whether a spicy diet truly reduces the likelihood of premature death or elevates metabolism in a significant way, the fact of the matter is that there is no real downside to being a spice girl. Contrary to popular belief, spicy foods will not cause ulcers, in fact capsaicin may even protect against them. So apart from potentially aggravating existing digestive issues like IBS, IBD and Chron’s, consuming chili peppers is safe. Provided of course they’re not the Carolina Reaper or another clearly bro-named variety like the Ghost pepper, Infinity Chili, or Trinidad Scorpian Butch T.
What capsaicin suffers from in the nutrition world is not a lack of research or understanding, but a strong history of folklore and our deep desire for quick-fix weight loss solutions. Sure, consuming some szechuan peppercorn may clear your sinuses, but it won’t cure a cold. And despite the “I’ll-try-anything” desperation that comes when a birth date is overdue - spicy foods won’t induce labour either. And finally, the metabolism boosting capsaicin pills, or cayenne pepper hacks popularized on the internet are just another cash grab by a genetically blessed, and likely very hungry, fitness influencer. But with all that said, consuming chili peppers, in whatever quantity and format you prefer, can be a delicious and entertaining way to spice up your life. Realistically you won’t see any effects on your metabolism or weight, but who knows, maybe you’ll wind up living longer than your extra-mild friends.
That’s been the bite for today, stay hungry.