The Science of Spice – Ciara Barrett

We, as Brits, love spicy food. Studies show that as a nation, Chinese and Indian are our all-round favourite cuisines even after our own classics like fish and chips or the humble traditional roast. This leads us to ask why and how do so many people, despite not having grown up eating spicy, rich food, love it with such a passion? These foods originated from other parts of the world and even the growing effect of multicultural communities doesn’t explain why we have grown so diverse in our food choices. Another possible question is why is there such a big divide between chilli lovers and haters? There are those that have stuck to the British stereotype of preferring milder food, which is perfectly fine, but what determines this difference?

Diving into the chemistry side, capsaicin is the most common molecule found to give chillies their heat, belonging to the capsaicinoids, a class of compounds found in almost all peppers. It stimulates the pain receptors in your mouth which explains the burning felt when eating spicy food. This is the same receptor that responds when you touch hot objects by transmitting pain to the brain. (As a side note, capsaicin is hydrophobic, meaning it repels water, which explains why drinking water really won’t help to wash it down when you accidentally put too much chilli sauce on your food.)

There are a number of relatively untested theories as to why we love spicy food (spicy food here meaning food containing chillies and not food with actual spices like ginger, paprika, etc.) and why some people can tolerate higher levels of heat than others who prefer none at all.

One possible explanation is that spice tolerance is genetic; some people have less responsive receptors which gives them a high tolerance. In the same way that people may have a naturally high pain tolerance (read: fire eaters), people with a high spice tolerance aren’t affected as much by the effects of spicy food and therefore feel less pain from it and can eat hotter chillies to get the same effect as someone with more sensitive receptors. Similarly, fondness of strong flavours has been shown to have genetic factors in some people too, so some people really are born with it.

The next theory is that tolerance of spice is an environmentally influenced trait. People who eat spicy food regularly and/or from a young age gain a greater tolerance and don’t feel as much burn from it. It was thought that people who ate lots of hot chillies from a young age had damaged nerve endings in their taste buds, but taste buds only have a lifespan of 10-14 days so, like burning your tongue on a hot drink, the damage would be non-permanent even if chillies did burn off your taste buds. However, with this myth busted, it is in fact possible to become used to a certain level of spice by eating it from a young age and thus be able to tolerate hotter food later in life because you’ve become accustomed. This redefines your threshold of what constitutes ‘very spicy’ relative to others and is known as desensitisation.

The final, least tested theory is that for some people, eating spicy food is a “thrill-seeking activity”. Like touching a hot surface, the pain receptors transmit a message to the brain that this food is possibly dangerous, but the logical side of the brain knows it isn’t. This is a similar situation as coming down a rollercoaster- once the body realises this seemingly dangerous activity isn’t dangerous at all, it gives a thrilling rush of endorphins.

These theories all aim to explain why some people go for the Extra Hot option at Nando’s and how this is possible in an infamously “bland” society like Britain. They’re all relatively uncharted so for now it will remain a mystery as to why we love spicy food; maybe it’s because it just feels like a rollercoaster.

Chocoholics Anonymous

Vanessa Kam

Oh, sugar!  Did I just single-handedly finish that 12 pack of creme eggs for lunch?

Perhaps you were disciplined enough to give chocolate up for lent, or maybe you ate all your Easter eggs in one day. Either way, it begs the question, is chocolate really addictive?  Can we really become hooked on certain foods?

How do we define food addiction?

Until recently, there was no recognised psychometric to identify food addictions.  Scales existed for binge eating, emotional overeating, eating disorders and alcohol consumption, but none to explore the behavioural indicators of food addiction.

In 2009, researchers from Yale University developed the Yale Food Addiction Scale to fill this gap, updated to version 2.0 in 2016.  This is a set of 35 questions on eating behaviour derived from criteria for substance use disorders, drawing parallels between drug addiction and food addiction. Each question is scored, from ‘never’ to different frequencies within a month, week or daily.

The scale shows how eating habits may fall within the boundaries of substance abuse:


Source: Yale University

With a diagnostic tool for food addiction settled, what actually happens in the brain when we crave another bar of chocolate; when we snap another chunk off and let it melt in our mouths?

The biological basis of chocolate addiction

The simplest explanation for chocolate addiction is its activation of dopamine and opioid systems in the body, providing a sense of reward.  A study assessed the psychological response of subjects to chocolate using drug-effect questions, normally used to judge well-being, euphoria, and other sensations after taking drugs like morphine.

They found that chocolate consumption caused an increase in drug-like ‘psychoactive’ effects. Psychoactive substances change brain function and alter mental processing. The effects were proportional to the chocolate’s sugar and cocoa content and associated with a desire to consume more.

In another study, MRI scans of brain activity in young female subjects showed that those who scored higher on the Yale Food Addiction Scale had higher activation in brain regions regulating rewards and cravings when anticipating a chocolate milkshake.

These females also displayed lower activity in inhibitory brain regions while consuming the milkshake. This suggests that these individuals had less inhibitory control or a reduced feeling of fullness while eating palatable foods. These responses are strikingly similar to brain scans of drug users when presented with their substance of abuse.

Chocoholic or social animal?

Despite the evidence of the psychoactive effects of certain foods, many researchers remain reluctant to recognise ‘food addiction’ per se as it implies substance-based dependence, where specific nutrients evoke addiction.

Chocolate, for example, does have pharmacologically active substances like caffeine, theobromine and phenylethylamine. However, studies have shown that consumption of white chocolate, which does not contain cocoa and therefore lacks the above substances, provides a similar craving relief.  This suggests that our love for chocolate is less due to its pharmacological constituents and more to do with the combined sensory experience of aroma and texture from fat and sweetness from sugar.

Rogers and Smit offer an intriguing alternative perspective, citing the psychosocial factors behind why we might be self-proclaimed chocoholics.  They argue that chocolate is labelled ‘nice but naughty’ by society, a sugary, fatty but extremely tasty snack which ought to be eaten with restraint.  Attempts to restrict desires for chocolate only exacerbate them, so we become more conscious of our consumption, accompanied by feelings of guilt and a lack of self-control.

In a study comparing the attributes of 50 food items compared to their frequency of consumption, chocolate scored highest in ‘difficult to resist’ but was ranked 17th in consumption.  In contrast, tea and coffee ranked 18th and 25th respectively for the difficulty to resist, but were the most frequently consumed.  This is because tea and coffee are more socially acceptable sources of pharmacological stimulation, whereas the hedonistic effect of eating chocolate, an unhealthy treat, is negatively perceived as overindulgence.

In essence, Rogers and Smit claim that chocolate is most frequently pointed towards as an addictive substance because it is the one food most people try to resist; there is not enough evidence to demonstrate it has the same potent neuroadaptive effects as drug addictions.

The next time you find yourself proclaiming chocoholic status, ask yourself this: am I really addicted to chocolate, in the sense of cravings, tolerance, withdrawal, inhibited control, and impaired lifestyle, or am I simply responding to environmental or emotional cues, desiring the pleasure of some good old chocolate?


Virtual Reality Food

Rachel Jones

Virtual reality food is where the user can see, taste, feel, smell and hear themselves eating a food, but they are not actually eating. This is being developed by a number of independent laboratories and companies, but it is being led by Project Nourished.

Project Nourished is developing a range of products to be used together to give a virtual reality eating experience. The headset allows the user to see the 3D-printed food as the food that is being imitated and the environment in which the food is being enjoyed. A aromatic diffuser gives an appropriate scent to the food. A bone conduction transducer is similar to headphones, but the sound waves are transmitted through the skull in a way that allows the sound to be heard as if it was coming from the jaw.

It also includes a gyroscopic utensil, loosely resembling a spoon, that is necessary for the movements of the user to be translated to virtual reality. The virtual glass seems to have a similar function to the utensil; telling the headset to display the process of drinking, but may also inform the headset that the user is an alcoholic drink and cause a visual simulation of intoxication for those who cannot consume alcohol. A hydrocolloid-based 3D printed food is used to confer taste, texture and consistency, as it is emulsifiable and low caloric.

There are many theoretical applications for the Project Nourished experience, ranging between leisure to  therapeutic use. A lot of sales will be made by those who are looking for something to help with weight loss. Users will benefit from the system by allowing themselves to give into unhealthy cravings without consequence through the device. Project Nourished intends to simulate food that is being eaten but does not actually exist, in fictional places. Long distance relationships could be supported by the technology, as couples will be able to experience dining together from locations continents apart.

Good_Food_Display_-_NCI_Visuals_Online simple wikipedia

Image Credit: Simple Wikipedia

Many people cannot eat certain foods they love; people with allergies, diabetes, problems with chewing, swallowing and digestion, or even astronauts who miss foods that cannot be taken into space. Project Nourished aims to supplement their lifestyle with the experience of eating what they want to eat. In contrast to this, the devices may be used to acclimatise fussy eaters to acquired tastes, particularly in children who will not eat healthy foods. This approach could also be carefully taken in eating therapy for patients with eating disorders, weaning them onto the idea of eating and developing healthy eating habits without the stress of calorific consequences. Prader-Willi syndrome is a condition in which, among other symptoms, the patient does not receive a ‘full’ signal and will constantly eat as they feel as though they are starving. Project Nourished claims that their technology could be used by these people to combine eating with negative stimuli, associating eating with unpleasant memories.

What does science say about the effectiveness of these applications? Studies into mimicking food consumption without the calorific intake modelled with chewing gum generally conclude that chewing gum reduces appetite and results in decreased food consumption. One may question whether these findings would apply to virtual eating. Excessively controlled dieting is known to be less easily maintained and so diets fail more when they are too strict; maybe treating yourself with unhealthy foods, without metabolic consequence, will make dieting more successful.

There are apparently no dedicated Project Nourished team members advising on the psychological consequences of virtual eating. One would hope that the company bases suggestions of therapeutic applications on fact, and that suggestions of effective treatment of Prader-Willi syndrome, eating disorders and weight loss by this technology are backed up by reliable studies. A concern about the use of this technology is that users will replace too much of their diet with a replacement to food, aiding eating disorder development by enabling the users to live without food more easily.  

The use of the products to stimulate alcoholic intoxication is not expanded upon on the project’s website. If it is for use in treating alcoholics, its efficacy would be questionable, as it would not satisfy the chemical addiction involved in alcoholism unless alcohol is provided. If it is for use by people who wish to experience drunkenness without the damaging effects of alcohol consumption, whether they have a medical condition affected by alcohol or not, the simulation cannot mimic many aspects of drinking, such as the specific mood and behavioural changes, which are the main draw to drinking many people feel.

Many of the most interesting psychological and medical applications of virtual eating technology have yet to be seen as this is state-of-the-art technology, and will likely be studied extensively upon product release.  

Why Do I Hate Marmite?

Helen Alford

Ah, marmite. The notorious dark brown, gloopy sludge (I’m hard-pushed to call it a food) is a byproduct of beer brewing. The yeast extract left over from brewing lager, bitter, and ale is mixed with vegetable and spice extracts, along with some other ingredients that are ‘trade secrets’. The manufacturing process sounds just as unappetising as the end product tastes.

The spread is behind one of the UK’s most divisive advertising campaigns – ‘Love it or hate it’. Polling agents YouGov ran a poll in 2011, asking 2,500 British adults whether they loved, hated, or had no opinion on marmite. The results were 33% for both love and hate, with 27% remaining neutral. That’s a pretty even split. Personally, I just can’t understand how anybody could willingly eat this vile excuse for a condiment. But clearly, people do. So what makes our palates so different?


Love it or hate it? (Image Credit: Helen Alford)

Taste and smell have long been evolutionary survival tactics. If something doesn’t taste right, we know to avoid it. Bitter tastes usually mean poison, while a sulphurous smell can be associated with something harbouring dangerous bacteria. The ‘survival’ role of these senses has declined as we have developed ways to keep food safe and the availability of food has grown. Even so, we still use these senses to judge food. If milk smells bad, we don’t put it in our tea. Evolution can explain the general aversion to bitter-tasting foods like grapefruit and broccoli, but what about more personal preferences?

Babies may inherit food preferences from their mothers. The flavours are transferred to the child from the mum through the amniotic fluid. One study found that babies whose mothers consumed carrots during the last stage of pregnancy were more likely to eat carrot-flavoured food compared to babies whose mothers did not eat carrots. The same principle could potentially be applied to other foods.

Another biological factor that can account for differing tastes is the amount of taste buds on an individual’s tongue. Taste buds detect the five tastes: sweet, sour, salty, butter and umami (savoury). “Supertasters” have more fungiform papillae – projections holding taste buds – and so taste things with much more intensity. They also have an increased sensitivity to bitterness. Research has shown supertasters have reduced preferences for foods including coffee, mushrooms, gin, tequila, green tea, and cabbage. Average tasters usually have a more accepting palate.

To try and understand why supertasters react negatively to certain foods, scientists are considering a gene named TAS2R38. The gene encodes a protein which is a bitter taste receptor. People who have a version of the gene that is very influential in tasting (as opposed to a non-tasting or subdued version) may be supertasters. Fussy eating could well be the results of genetic factors like this.

A person’s taste can evolve through the influence of various psychological factors. For example, association of a food with a feeling or emotion can affect the way the food is perceived in the future. If a person eats a food which makes them ill, chances are they won’t like that food anymore. The appeal of the food in terms of all 5 senses is diminished.  In contrast, if a person associated a food with being exceptionally positive, they’re probably more likely to keep eating it.

Interestingly, recent studies have shown that people who enjoy bitter foods like gin may have psychopathic traits.  One experiment showed that the ‘agreeableness’ of a person is negatively correlated with a liking of bitter foods.

Societal influences can also play a role in determining what people like and don’t like. As children, we naturally have a fear of trying new things. It’s possible that people whose parents encourage them to eat new foods regularly could grow up to be less fussy than those who stuck to a more restricted diet. Adults are expected to be less fussy than children, and so may be forced to consume foods they don’t like to ‘fit in’. Olives seem to be the prime example of this. Luckily, research shows that the more times you eat a food, the more you grow to like it.

Food preferences are down to the interaction of numerous factors. Gene variation, upbringing, number of taste buds, psychology, society, experience… Call me narrow minded but none of these factors could ever explain to me the love people have for marmite.