Turning up the heat on chillies and their health benefits

If variety is the spice of life, then for some, a hot chilli dish is the ultimate way to add spice to life. But outside of the Mexican fiesta party happening inside your mouth and the waterworks from your sweat glands, could there be some benefits for your health? It's time to turn up the heat on chillies as I look at the science and health benefits linked to eating them.

Links referred to in the podcast

• Effects of capsaicinoids supplementation on metabolic syndrome https://www.nature.com/articles/s41598-020-77983-2
• Effect of capsaicinoids on sports performance https://journals.humankinetics.com/view/journals/ijspp/16/4/article-p464.xml

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Transcript

If variety is the spice of life, then for some, a hot chilli dish is the ultimate way to add spice to life. But outside of the Mexican fiesta party happening inside your mouth and the waterworks from your sweat glands, could there be some benefits for your health? It's time to turn up the heat on chillies as I look at the science and health benefits linked to eating them.

Chilli peppers are perennial shrub varieties of the berry-fruit of plants belonging to the genus Capsicum. You’ll see the terms chilli, chilli pepper and capsicum used interchangeably. Chillies are an excellent source of provitamin A compounds which give them their wide variety of vivid colours. You’ll also find plenty of vitamin C in them too.

They are used in culinary dishes all over the world to add spice and ‘kick’ to food. The substance that gives chilli peppers their spicy heat when eaten or applied topically is the compound capsaicin and several related chemicals, collectively called capsaicinoids.

That capsaicin is not there for our culinary benefit; it’s part of the plant’s defence system against predators. And fun fact: there are even marine paints that have capsaicin added to them to deter marine life from adhering to the hull of ships.

When we eat capsaicin, it binds to pain receptors in the mouth and throat. This evokes a pain sensation via neuronal connections to the brainstem and thalamus where heat and discomfort are perceived.

The intensity of the ‘heat’ of chilli peppers is commonly reported in Scoville heat units. The intensity of chilli peppers can range from almost undetectable for the humble capsicum (also called a bell pepper) to around 10,000 Scoville heat units for a jalapeno pepper right up to the eye-watering and mouth-destroying heat of a habanero which comes in at a Scoville heat unit in the 6-figure range. One of the highest pepper ratings recorded comes in at 2.2 million for the Carolina Reaper pepper. For context, pure capsaicin has a rating of 16 million. Don’t try a spoonful of this at home. Ever. You’ll die.

Apart from the code red your mouth calls when you eat a hot pepper, that sweating you experience from eating a particularly spicy dish is your body reacting to the heat-generating spices in much the same way it reacts from the excessive body heat of exercise – it’s trying to cool itself off and maintain a safe internal body temperature. Black pepper and ginger, while not usually the first ingredients that come to mind when you think of ‘hot and spicy’, can also create comparable effects.

That bounce you get in heat production from a spicy dish does speed up your metabolism by a notch. It does this from capsaicin stimulating several neural pathways that result in adrenaline (also known as epinephrine) release from the adrenal glands. Now, a quick reading of popular health articles on the Internet all make similar claims that chillies are great for weight loss because of this metabolism boost. Don’t get too excited though. Generally, studies have shown that on average a meal containing a spicy dish can temporarily increase metabolism by about 8 percent over a person’s normal rate, an amount considered negligible. And this boost only lasts about 30 minutes after a meal. So, the effect is pretty small. And if you’re not a chilli lover, then all that pain and suffering is really just not worth it.

Fat oxidation appears to be increased following ingestion of capsaicin. But just because you can measure greater fat oxidation, get the idea out of your head that that means weight loss from more fat loss. All that is happening is that you’re using slightly more fat than carbohydrate stores at that particular time, but the law of energy balance will still apply if you’re not in a calorie deficit as longer-term, most energy needs will be met by fat as the primary source of energy.

But besides a slight uptick in metabolism, spicy foods may also increase feelings of satiety and fullness after a meal. There is a chemical receptor in our stomach called TRPV1 which can bind to capsaicin and which when activated, sends messages to the brain about how full the body is. In rodents, capsaicin appears to reduce food intake. Suppression of food intake and self-reported appetite has also been seen in humans with chilli consumption which appears to reduce food intake at a subsequent meal in the range of about 8 percent, primarily through a reduced fat intake. This suggests that weight loss from capsaicin, if it happens, is most likely from an appetite suppressant effect.

If you look at the wider research to do with capsaicin and human health, in particular metabolic syndrome and body weight, the results are not that impressive though. A 2020 review of this topic that included 11 human trials only found an effect of capsaicin on LDL-cholesterol and no significant benefit on blood pressure, triglycerides, HDL-cholesterol or blood glucose. And as for body weight, it was a clinically insignificant amount of just 190 grams. I’ll link to this review in the show notes. https://www.nature.com/articles/s41598-020-77983-2

But could that spicy kick also light a fire under your sports performance? There has been a small amount of animal and human research looking at capsaicin supplementation on exercise performance and endurance benefits. A 2021 review compiled this research together with 14 animal studies and eight human studies. Nine of those 14 animal studies appeared to show a benefit. But for the human research, three studies found a significant benefit in acute endurance benefits and two studies found a benefit in acute resistance exercise performance. I’ll link to this review in the show notes. So, maybe something is going on here, likely by adrenal effects on adrenaline release, but the effects are by no means consistent. https://journals.humankinetics.com/view/journals/ijspp/16/4/article-p464.xml  

So, let’s wrap all this up. If you’re looking for a different way to add flavour and spice to your food without turning to salt, then try using fresh or powdered chilli pepper in your next recipe. One of the most common side effects of capsaicin is a burning effect throughout the digestive tract so for those with acid reflux, heartburn or IBS, capsaicin-containing foods or supplements may increase your symptoms. But over time, your gut can become desensitised to capsaicin’s effects, reducing the uncomfortable feelings - allowing you to work your way up the Scoville heat unit ladder if you so desire. And if you can't stand the heat... pick a milder chilli.

So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.

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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.