Why can some people happily munch on chillies whereas others abhor the intense burning sensation that comes from eating them? It turns out that our genes play a part, writes Jennifer Bowden.
Q: I was fascinated by your February 4 column about genetic variance in taste receptors. I can’t tolerate chilli beyond a mild spice level. It’s not for want of trying. For me, a medium chilli drowns out every other flavour and removes the taste and nuance of different herbs and spices. My mouth and lips feel swollen (but aren’t), and my throat is sore. Perhaps my genes are to blame?
A: Capsaicin is the compound in chillies that elicits the spicy sensation that’s either loved or hated by many people. Although repeated exposure, particularly over a lifetime, can improve liking for chilli, research suggests there is undoubtedly a genetic component to preference. And we have a bunch of unsuspecting twins who dined on strange chilli concoctions to thank for these revelations.
Finnish researchers recruited a group of adults comprising 47 identical twin pairs, 93 non-identical twin pairs and 51 twin individuals (without their co-twin) for their chilli trials. The researchers fed the poor twins (depending on your perspective, I guess) standard strawberry jelly or one spiked with capsaicin and asked them to rate the pleasantness.
The researchers then used modelling to determine what percentage of chilli liking was associated with genetics. They concluded genetic factors accounted for 18-58 per cent of the variation in liking spicy foods, oral pungency and pungent sensations. The remaining proportion of enjoyment for spicy foods was the result of environmental factors, such as regular exposure to chilli, exposure from an early age, and so on.
The interesting thing about spicy foods is that our nervous system perceives the hotness of capsaicin as a burning sensation. So, chillies produce a pain response rather than being sensed by the body as a taste or smell. Notably, capsaicin from chilli activates heat receptors on nerve endings in our mouth and throat, on our tongue and even in our airways. So, you are correct in noting that you feel the burn in your mouth and throat. And accurate in deducing that you may be genetically different from your friends and family, who are better able to tolerate the capsaicin in chilli, even after repeated exposure.
Other irritants similar to capsaicin are oleoresin in ginger and piperine in black pepper. Wasabi, horseradish and carbon dioxide from soda also produce similar irritation to capsaicin, so chilli haters may be more inclined to eschew sparkling water and these other ingredients.
There is evidence that repeated exposure to capsaicin and chillies can produce long-term desensitisation, but the story is more complicated than that. Indeed, studies have found that only a slight desensitisation to pain occurs with regular consumption of chillies. So, something else must happen (other than pain reduction) that results in people becoming chilli lovers.
There is evidence that those who like chilli after repeated exposure have learnt to enjoy the oral-burn sensation. Psychologists rightly wondered what motivated some people to seek out that pain. They found the personality trait of “sensation seeking”, in particular, was associated with liking chilli. Sensation seeking exists on a spectrum, and people higher on the spectrum seek out varied, novel and intense experiences for the sake of having new and different sensations. These may include adrenaline-pumping activities, trying a new dance class or restaurant, or even tasting weird and wonderful new cuisines (attendees at the Wildfoods Festival, perhaps?).
All this affirms we are complex and variable people with different food preferences based not only on our culture and upbringing but also on our genetics and personality. What is tasty and enjoyable for one person can be disgusting and repulsive for another, and there is nothing wrong with either response. On that note, I’ll continue ordering my butter chicken as mild, thanks.
