Instant noodles are banned for being too spicy! There is so much science behind eating spicy food

About one-third of the world's population eats chili peppers every day. For thousands of years, people have endured the stinging and burning sensations of chili peppers while diligently incorporating them into their diets. Why do people like spicy food so much? Scientists in different fields have given possible revelations from different aspects, but they cannot fully understand why humans prefer chili peppers so much. Eating those super spicy peppers may cause serious physical discomfort, so please eat according to your ability.

Written by | Xiaoye

In the hot summer, it is the best time to eat spicy food. However, some people love spicy food, while others try their best to ban spicy food. According to media reports, the Danish Food Administration asked Samyang Foods to recall three types of spicy turkey noodles produced by the company because the chili content was "too high and may cause acute poisoning to consumers."[1]

Coincidentally, Germany also banned the sale of a brand of devil pepper potato chips nationwide after a 14-year-old student died of food poisoning hours after eating them. [2]

It seems that chili peppers are just like the old saying: "One man's meat is another man's poison." What is the scientific reason behind such divisive evaluations?

Nobel Prize winner reveals the mechanism of spicy food

When you eat chili peppers, you will first feel a stinging sensation in your mouth, followed by a burning sensation, as if there is a blazing fire burning in your mouth. This real pain and illusory heat are the result of the capsaicin in the chili pepper and the capsaicin-specific receptor in our body, the vanilloid receptor type 1 (TRPV1). In addition, it is the study of capsaicin receptors that made American neuroscientist David Julius one of the winners of the 2021 Nobel Prize in Physiology or Medicine [3].

As early as the late 1990s, David Julius led a team at the University of California, San Francisco, to actively analyze how capsaicin causes us to feel when it comes into contact with it. Through various experimental methods, he finally successfully identified and cloned TRPV1, demonstrating the basis of the body's perception of spiciness at the molecular level: TRPV1 is an ion channel activated by pain and heat (noxious heat ≥42°C), which specifically recognizes afferent neurons of noxious stimuli and is widely distributed in multiple tissues and organs of the body. When the mouth comes into contact with capsaicin, TRPV1 is immediately activated, generating electrical signals that are transmitted to the brain along noxious afferent neurons, and the brain interprets these signals as "painful" stimuli. From a scientific point of view, the feeling of spiciness is defined as "pain" [4-5].

In addition to pain, how does capsaicin make us feel hot? The heat generated by eating chili peppers or chili-like substances is not the result of physical heating, but after we are spicy, we become more sensitive to heat. When TRPV1 is activated by capsaicin, the threshold for temperature perception is also lowered. Even a body temperature of less than 42°C will induce TRPV1 to transmit harmful heat signals to the brain, causing the brain to have an abnormal perception of "heat". Therefore, under the dual stimulation of capsaicin and temperature, the excitability of sensory neurons expressing TRPV1 receptors is also enhanced. In summary, our feelings are "abnormally" amplified, and our mouths are like "breathing fire".

David Julius used capsaicin to identify TRPV1, an ion channel activated by painful heat.

Next, our body also responds to the stimulus, which is still related to the TRPV1 receptor. TRPV1, a non-selective cation channel, is expressed in both neural and non-neural tissues. Its activation leads to a large influx of calcium ions, increases the calcium ion concentration in non-neural tissues, and mediates the release of a variety of neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP). The former can induce vasodilation, increase vascular permeability, lead to edema, stimulate mast cells to release inflammatory mediators, and induce leukocytes to release proteases and reactive oxygen species. CGRP relaxes arteries, regulates skin blood flow, and induces neurogenic inflammation. [6-7] As a result, our body induces an inflammatory response out of "self-defense", and begins to sweat, have a runny nose, blush, swell, etc.

Spicy food: Pain and happiness

Why can’t humans stop eating spicy food when it causes us pain and heat? Records show that the earliest use of chili peppers can be traced back to 7000 BC in Central America[8], and an article published in Science[9] revealed that humans began to grow and eat domesticated chili peppers from the Bahamas to the Andes 6000 years ago, and in some areas, chili pepper cultivation even predates the emergence of pottery. During the Age of Exploration in the 15th century, Columbus and other early explorers brought chili peppers from the Americas to the Old World of Europe, and then spread them around the world through sea routes and the Silk Road. Today, chili peppers have become an important part of the diet in many countries around the world, including West Africa, East Africa, India, Southeast Asia, parts of China, South Korea, and more[10].

For thousands of years, people have endured the burning pain of chili peppers while diligently incorporating them into their diet. Paul Rozin, a psychologist at the University of Pennsylvania, pointed out that about one-third of the world's population eats chili peppers every day. Why? Simply put: they like it.

To date, most scientists still do not fully understand why humans love chili peppers so much. Scientists from different fields have given possible explanations from different perspectives[11].

Biologists explain from an evolutionary perspective why eating chili peppers has become a cultural preference in certain regions. Jennifer Billing and Paul W. Sherman of Cornell University in the United States analyzed more than 4,000 recipes from 36 countries around the world and found that there is a certain relationship between the average temperature of a region and the proportion of spicy food in the diet[12]: the higher the average temperature of a region, the higher the proportion of spicy ingredients used in local cuisine, because hot weather can easily cause a large number of microorganisms to grow quickly in food, and spicy substances have a bactericidal effect, ensuring food safety. People in cold regions also prefer spicy food, which may be related to the physiological effect of eating spicy food that produces a sense of heat and causes an increase in body temperature. A study published in Bioscience, Biotechnology and Biochemistry in 2007[13] pointed out that the intake of capsaicin will increase the core and surface temperature of the body, which can play a certain role in keeping out the cold.

In addition, genes also seem to play a role in the preference for spicy food. A paper published in Physiology & Behavior in 2012[14] used Finnish twins as subjects and first asked them to rate their preference for spicy food. Then, a quantitative genetic model was used to analyze the influence of genetic and environmental factors on the preference for spicy food. The results showed that people who do not like spicy food give higher scores for the spiciness of spicy food, but lower scores for the pleasure it produces. Genetic factors explain 18% to 58% of this preference, and the rest is due to environmental factors, indicating that the preference for spicy food may also have a genetic tendency.

The theory of "benign maochism" in psychology also provides a reasonable explanation to help understand people's motivation to eat spicy food. Benign maochism refers to individuals enjoying negative experiences that are misinterpreted by the body or brain as threats. Once the individual realizes that there is no real danger, the difference between cognition and physiological response produces a pleasant excitement. Therefore, humans' love of spicy food is a behavior of actively seeking negative experiences. Rozin led a team to conduct research and verified eight types of experiences that belong to benign maochism[15]. Among them, eating spicy food belongs to the category of burning pain. When an individual eats spicy food, the body sends a "false alarm" that it is threatened, causing the body to make a series of defensive reactions, but at the same time the individual realizes that there is no danger, and the pain of eating spicy food turns into a stimulating enjoyment. In addition, the study also proposed that when the spiciness of the food consumed by an individual is just slightly lower than his or her tolerance, the most pleasant spicy food experience may be produced, but further verification is still needed.

How much spiciness can you handle?

People who love spicy food are often quite confident in their ability to tolerate spiciness. So, how to quantify and evaluate this ability? The Scoville Scale provides a detailed reference measurement.

In 1912, American pharmacist Wilbur Scoville designed a subjective evaluation method called the Scoville Organoleptic Test to measure the capsaicin content in different pepper varieties. He used his last name as the unit of capsaicin content, called the Scoville Heat Unit, abbreviated as SHU. However, his experimental method mainly relied on the subjective feelings of the subjects. Later generations developed a more objective "high performance liquid chromatography" method for measurement, but the capsaicin content unit SHU was retained and is still used today [16].

Take the following table as an example. Bell peppers contain no capsaicin at all, so their Scoville index is 0; Mexican peppers are between 2,500 SHU and 10,000 SHU. The pepper with the highest Scoville index is also the hottest pepper in the world today - Pepper X, which has a spiciness of more than 2.69 million SHU. However, this pepper is a cultivated variety. It was cultivated by Ed Currie, an American pepper breeder and creator of the Carolina Reaper, which was once the hottest pepper in the world, over a period of 10 years. Through selective breeding, Currie gradually allowed the pepper hybrids to show the desired characteristics. After more than ten generations of breeding, the characteristics were stabilized and finally produced the strongest spiciness [17]. However, eating these super spicy peppers may cause serious physical discomfort, so please eat according to your ability.

A ranking of the hottest peppers in the world, measured using the Scoville heat scale.
If you are not familiar with the numerical measurement of spiciness using SHU, then my country, as a country that loves spicy food and produces a lot of chili peppers, also has a traditional spiciness rating system: "mildly spicy, medium spicy, very spicy, extremely spicy" and so on. Mildly spicy food is characterized by a very slight irritation on the tongue and mouth, which most people can tolerate. When the spiciness is adjusted to medium spicy, the tongue and mouth can already feel a certain tingling and burning sensation, which is the taste of the home-cooked tiger skin green pepper. When eating very spicy peppers, the tongue and mouth will experience a significant burning sensation, and people who are not good at eating spicy food may start to sweat, have a runny nose, sneeze, or even cry from the spiciness. Extremely spicy peppers, such as the shabu-shabu peppers in Yunnan, are rarely eaten directly by people because the irritation they produce is unbearable for most people[18].

The above spiciness levels are mainly based on personal subjective feelings and lack certain uniformity and accuracy. In 2006, the School of Food Science and Technology of Hunan Agricultural University was commissioned by the National Standards Committee to formulate national standards for the spiciness of chili peppers and chili pepper products. Since then, local governments and enterprises have also begun to define spiciness more accurately. In 2014, the Department of Food Science of Sichuan Tourism College and the Key Laboratory of Culinary Science of Sichuan Higher Education Institutions combined the Scoville Index, the content of capsaicinoids in food, and the traditional spiciness grading concept to classify 123 Sichuan dishes into four levels: slightly spicy, medium spicy, spicy, and very spicy [19].

The top 20 spiciest Sichuan dishes in the study.

In 2020, the Institute of Urban Agriculture of the Chinese Academy of Agricultural Sciences and a team from an enterprise published a paper in the International Journal of Food Properties on the use of the Li Spicy Unit (LSU) to measure the spiciness of hot pot seasonings such as hot pot bases[20]. The team used "degrees" as the unit to divide the spiciness of hot pot into six levels: mild (9°~29°), low (30°~39°), medium (40°~49°), high (50°~59°), extra spicy (60°~69°), and extremely spicy (≥70°)[21], helping consumers to more intuitively choose spicy food that suits their taste and tolerance.

Scientific Tips to Relieve Spicy Spiciness

Given that everyone has different tolerance to spicy food, if we unfortunately overestimate our tolerance and end up with a very spicy tongue with an unbearable burning sensation, how can we effectively relieve the spiciness?[22]

The first effective method is to destroy the binding of capsaicin to the TRPV1 receptor. Since capsaicin is only soluble in oil and alcohol, but not in water, drinking water cannot relieve the spiciness. Instead, it will spread the capsaicin throughout the mouth and even the throat, making the spiciness even spicier. Therefore, compared to drinking water, taking a mouthful of milk or other dairy products can help relieve the spiciness. Dairy products not only contain oil, but also casein, which is a non-polar molecule that can bind to capsaicin, which is also a non-polar molecule, to dissolve it and eliminate the burning sensation. Therefore, foods such as whole-fat ice milk, whole-fat yogurt, or ice cream are all "experts" in relieving spiciness.

In addition, starchy foods can also play a certain role in relieving the spiciness, such as rice, bread, potatoes, etc. Although starch cannot dissolve capsaicin, it can absorb capsaicin like a sponge, shortening the duration of the spicy taste and eliminating the spicy feeling. So if there is no milk, you might as well eat a few more mouthfuls of rice when you accidentally get spicy.

The second method is to interfere with the brain's perception of spiciness, such as sucrose. On the one hand, the stimulation of spicy and sweet tastes acts on different receptor cells in the mouth. After activation, these cells will interact with each other and interfere with the brain's perception of spiciness alone. On the other hand, the brain will release analgesics after receiving sweet stimulation to relieve the stinging sensation caused by spiciness.

The third method is to use acidic substances to neutralize alkaline capsaicin, such as lemon, sour plum, sweet orange, etc., which can alleviate the spicy feeling.

In addition, an article published in the journal Physiology & Behavior in 2018 proposed an interesting finding [23]: Completely blocking nasal airflow can reduce the perception of capsaicin by 50%. The reason is that after the nostrils are closed, the surface temperature of the tongue will decrease, and the temperature reduction will reduce the possibility of activating TRPV1. Maybe in the future, when you are choked by spicy food, you can try pinching your nostrils to relieve the spiciness with physical methods?

Samyang Spicy Chicken Noodles was once selected as the most satisfactory Korean instant noodle brand for Chinese consumers in the 2021 Korean Brand Awards, but now it has been unexpectedly banned in Denmark. After all, mainly due to health concerns, not everyone can accept instant noodles with a spiciness of more than 4,400 SHU, especially for children with more sensitive taste and digestive systems and frail adults, who will face a higher risk of adverse reactions including nausea, vomiting, gastrointestinal side effects, etc. Therefore, spicy taste can add vitality to life, but at the same time, be careful not to add burden to your health.

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