We eat poison

A variety of spices in bowls on a white background, exploring the mouth's receptor for taste.
We all know the feeling — some spicy dish attracted our attention, and we dared to try it, only to feel a fire starting in our mouths soon after. Some enjoy this feeling, while others avoid it. Some love the spiciness of red pepper, some prefer hot mustard or raw garlic, and others cannot imagine their plate without horseradish spices and sauces. Whatever it is we’re eating, this taste is the result of our body’s absorption of the spicy chemical weapons that evolution has given plants for protection.

Some Use Spices

Some plants, such as pepper, garlic, and mustard, evolved to produce particular substances to protect themselves from bacteria and fungi. However, they were not the only ones suffering from the negative impact of these microorganisms. Our food also fell prey to them. Later, people noticed that if those special herbs were added to food, it stayed fresh for a longer time. That’s how the first preservatives appeared — people began using what we now call spices. Though, it took time to get used to these natural preservatives: some didn’t like the taste of pepper, and some got indigestion from mustard seeds. However, residents of hot regions eventually realized that the temporary discomfort from spicy food was a better prospect than death from a gastrointestinal infection.

Gradually, people adapted to the plants’ “chemical weapons,” and spicy dishes began to take root in the cuisines of the tropical and subtropical regions. However, for the inhabitants of the temperate climate zones, where, due to the moderate temperatures, food did not go bad for a while, spicy food often seems inedible. Northern people began to use spices relatively recently, with the establishment of trade routes between Europe and Southeast Asia. Prior to this, they preserved food by either salting or freezing it.

Travel guides to South America, Africa, and Southeast Asia often recommend eating spicy food. Countries with hot climates often experience problems with sanitation and clean drinking water, and spicy food may reduce the risk of getting an infection.

Savory, Spicy, Scorching

The red chili pepper and other chilies and fruits of the Capsicum shrub family allow a person to experience the most pungent spiciness possible. Capsaicinoids, a group of alkaloids of plant origin, are to blame.

Even in the hottest pepper, the content level of capsaicin is safe, but the substance itself is a very strong irritant. Those who work with pure capsaicin or capsaicinoids are required to wear gloves, goggles, respiratory protection, and even a full-body protective suit.

Most of the capsaicin is found in the white flesh of the peppers and their seeds, so the burning sensation is especially overwhelming when we chew the peppers’ seeds. In the oral cavity, capsaicin binds to TRPV1 receptors. These receptors then transmit a signal to our brain, indicating an increase in the mouth’s temperature.

The TRPV1 receptors are not meant to recognize capsaicin. They get activated once the temperature rises above 109.4 °F, and then they immediately send a signal to the central nervous system reporting the body is overheated. This way, they warn, for example, about the dangerously hot food or embers. Nonetheless, these natural sensors can identify some substances contained in the “hot” food. Capsaicin and its derivatives protect peppers not from microorganisms but from mammals.

Why We Perceive Spice

Capsaicin acts on our “pain” neurons, the membranes of which contain TRPV1 receptors. In turn, this receptor reacts to both chemical and physical stimuli, such as acidification of the ­medium and an increase in temperature above 109.4 °F.

TRPV1 is part of the TRP family of thermoreceptors responsible for thermoregulation in warm-blooded animals. Therefore, the activation of this receptor is expressed as either a burning sensation or stinging pain.

There are heat receptors in the oral cavity of humans and other mammals, but not in the mouths of birds. And peppers apply this fact to their advantage: they use birds as a means of transportation! Inside the digestive system of birds, seeds can travel safely over long distances and conquer new territories. The Aztecs also exploited birds’ lack of heat receptors. The diaries of conquistadors suggest that the Aztecs intentionally fed chilli peppers to canaries to give their plumage a red color.

Mind Games

So, TRPV1 receptors’ multitasking causes our nervous system to confuse a chemical signal with a thermal signal. That is why we eat something extremely spicy, the brain thinks we made a mistake of swallowing something hot. To relieve this 

feeling, the central nervous system takes measures to cool the body. It speeds up the metabolism, accelerates blood circulation, and you begin to sweat profusely. In the blood, the concentration of natural painkillers — endorphins — increases. The nasal mucosa becomes inflamed, tears start to flow, and your eyes close: the brain sends a signal to the eyelids to protect the organs of sight from the non-existent high temperatures.

Sure enough, sensations after consuming an unexpectedly hot dish will not be pleasant. However, the amount of capsaicin and capsaicinoids contained in pepper or sauce do not cause physical damage to tissues and organs.

However, this does not mean that spicy food is completely safe. It still can cause indigestion, nausea, and vomiting. The brain receives a pain signal and decides to remove the culprit out of the body as quickly as possible, which triggers vomiting. This can be dangerous, though: during vomiting, acidic gastric juice gets into the esophagus, causing damage and inflammation to its lining. The degree of damage depends on the extent of irritation of TRPV1 receptors and the brain’s assessment of the “threat.”

The Scoville Heat Scale

Oddly enough, the chili pepper is not at all related to the country of Chile, whose name comes from the Quechua language, and instead originates from the Nahuatl word “chīlli,” meaning “hot pepper.”

Scoville scale, used to assess the hotness of a pepper. The higher the Scoville score, the hotter the pepper or dish is.

Pepper Pungency

There are several scales of measuring the “hotness” of food products. Scientists, cooks, and food technologists usually use the Scoville scale, which was introduced more than a century ago. In 1912, the American chemist Wilbur Scoville first proposed to use a quantitative scale based on taste sensations to assess the pungency of pepper. It was constructed as follows: extracts from different peppers were dissolved in alcohol, and then a drop of this solution was combined with sweetened water. Later, five professional tasters tried the mixture. If they experienced a burning sensation, the solution was diluted and offered again to sample. The procedure was repeated until the spiciness disappeared. The unit of measurement in the Scoville scale was the volume of water that was required to dilute the extract to the point at which the “pepper solution” was no longer an irritant. The higher the score on the Scoville scale, the more pungent the pepper or dish.

The spiciness of the bell pepper on the Scoville scale is zero. Tabasco sauce corresponds to 2,500 units, while jalapeño reaches 3,500–10,000 units. Some restaurants in the US offer their visitors the Dave’s Gourmet Insanity Sauce, the spiciness of which totals at 180,000 units on the Scoville scale (however, it is forbidden to serve this sauce in most states).

The world’s spiciest dish is a curry called “The Widower.” It was prepared in 2013 and courageously eaten by the British doctor Ian Rothwell. The spiciness of this dish measures at 6,000,000 units on the Scoville scale. The chef prepared the sauce while wearing a mask, goggles, and gloves. Having finished one portion in two sittings (after eating part of the dish, Rothwell left the restaurant, took a 40-minute walk, and then returned and finished the meal), the British thrill-seeker said that the ascent to the top of Mount Kilimanjaro, which he had completed a year earlier, had been easier.

Extinguish the Fire…With Milk?

We often try to pacify the raging inferno in our mouths with water. This is useless! Capsaicin is a fat-soluble substance, so it’s impossible to soothe the receptors with water.

But your everyday glass of milk (not skim milk, though!) will do the trick to neutralize the action of capsaicin. Casein proteins and fats in milk attach to capsaicinoids and strip the molecules away from their receptor binding sites. This way, capsaicin loses its effectiveness, and the fire in your mouth fades out. So if you are not sure you like spicy food, have a glass of milk ready before tasting something fiery.

The Smell of Garlic

There is a lot of sulfur in garlic’s defense substances. However, unlike in peppers and mustard, the spicy and unpleasant-smelling substances are not always perceptible in garlic — they reveal themselves when something threatens its life. When a garlic clove is damaged mechanically, the enzymes break down neutral (in terms of smell) alliin to form the smelly allicin. So, allicin is the main component of the garlic odor, released upon cutting the plant. Later, allicin is converted into sulfur-containing organic compounds responsible for “garlic breath.”

There are four of them: allyl methyl sulfide, allyl methyl disulfide, allyl mercaptan, and diallyl disulfide. The worst “offender” is allyl methyl sulfide, as the body processes and disposes of it the longest. Allyl methyl sulfide is absorbed in the gastrointestinal tract and enters the bloodstream, eventually reaching other organs, such as skin, kidneys, and lungs.

The substance leaves the body with sweat, urine, and breath. Full excretion can take up to 24 hours, and during this time, the fans of this spice will be enveloped in a weak but distinctive garlic odor.

Why Do We Eat Poison?

Today, we have refrigerators of different sizes and a variety of ways of preserving food, all of which are less risky than adding spices to it. So why do we continue to use hot pepper, mustard, and garlic? It’s simple: they have other advantages.

Spicy and savory substances cause excessive salivation, which stimulates digestion. Irritation occurs not only in the mouth but affects the entire gastrointestinal tract, which accelerates peristalsis, a process responsible for moving food along your gastrointestinal tract.

There is yet another factor. The chemical “burn” of capsaicin or allyl isothiocyanate stimulates the release of endorphins, so you might grow to crave spicy foods over time. And of course now, unlike in ancient times, when our ancestors had to adapt to eating spices, many of us consider spicy foods to be just plain yummy.

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