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Like most folks, Zak White enjoys nights out with friends, a glass of wine or beer in hand, ready to dig into a freshly served meal.
Yet one tiny and seemingly harmless herb can spoil the whole mood for this self-proclaimed foodie.
“For some people cilantro tastes like soap, but I’ve never particularly found that,” he said. “For me, cilantro has a pungent bite to it. I don’t know what flavour it’s trying to be, but it’s certainly disgusting.”
Unlike subtler herbs such as bay leaves, whose flavour is barely perceptible in a dish, White said that cilantro permeates everything it touches. Even the tiniest sprinkle on his food can ruin what would otherwise be a good meal.
“If cilantro touches something that I’m having, I can take it off, but the taste remains,” he said. “It’s so distinctly disgusting and it’s inevitable. It overpowers everything with just a tang of ‘yuck.’”
“I hate it; it’s truly something inedible to me.”
As a vegetarian, White explained that avoiding cilantro is nearly impossible as it often sneakily makes its way on most menu items without ever being listed as an ingredient.
“A lot of restaurants in Victoria don’t have a large selection of vegetarian and vegan dishes,” he said. “Most restaurants will have some mundane (plant-based) burger or something, but any exciting vegetarian dishes, where it feels like they’re actually trying to promote other flavours, they’ve always got to add cilantro.”
Not limited to a lack of vegetarian offerings, the Victoria resident also said his dislike of the vibrant green herb prevents him from enjoying some of the world’s most flavourful cuisines, including Mexican and South Asian food, where cilantro is often baked into the dish.
“I’ve been experimental with my palates and I’ve tried all sorts of cuisines and dishes,” he said. “I’ve been able to appreciate many different flavours but I’ve never even remotely enjoyed cilantro.”
While some might say White’s hatred is simply due to being a fussy eater, University of Victoria postdoctoral fellow and olfactory expert Jamie Knight explained that the hatred for the herb is not a choice, but rather dictated by one’s genes.
University of Victoria postdoctoral fellow and olfactory expert Jamie Knight poses in her office holding sniffin’ sticks, a device used to test the sense of smell. (Olivier Laurin/Saanich News)
The culprit behind this aversion to cilantro is a small genetic variation in the OR6A2 gene, a very specific olfactory receptor found in up to 20 per cent of the population.
Unlike what some might think, it’s not the tongue or taste buds that determine people’s love or hatred of cilantro. Knight explained that, in this case, our sense of smell is solely responsible.
“Taste and smell are really closely linked,” she said. “The majority of what people think of as taste is actually smell. You can really only taste sweet, salty, sour, bitter, umami, and then all of the rest is smell.”
What we know as flavour is defined by both our sense of smell and taste, and is generated when the brain combines the two, creating a synthesis of the information, explained Knight. And to understand the science behind the curious case of cilantro, one needs to understand how the brain perceives smells.
“If you’re eating something, there are these tiny airborne molecules that enter your nose and they land on your olfactory receptor inside your nasal cavity.”
“When you’re chewing, it goes up through the back of your throat in an area called the retronasal (passage).”
In layman’s terms, Knight explained that olfactory receptors are specialized proteins, each shaped to respond best to countless different kinds of molecules.
“You can think of these receptors as little locks, and then every scent molecule as a key,” she said. “When the right key fits in that lock, the nerves will send a signal to your brain. The brain will then combine all of those signals from lots of different kinds of receptors all at once and then recognize that as a particular kind of smell.”
The infamous OR6A2 gene variation has been shown to be highly effective at identifying a specific organic compound.
“That receptor specifically is good at detecting a specific group of smell molecules called aldehydes,” he said. “That particular chemical compound is very strong, even in tiny amounts.”
Aldehydes, Knight explained, are found naturally in many herbs such as cilantro, citrus peels and cut grass, as well as in detergents, shampoos, and in fats and oils as they age and develop a rancid smell.
“At low level, aldehydes will come across as being like a fresh green, citrusy, bright scent,” she said. “But at a higher level it’s perceived as soapy or metallic and has a sharp and chemical smell.”
“How you smell it really depends on how you’re perceiving that odour.”
For people who have this OR6A2 gene variation, their taste for aldehydes will be heightened. So much so that they perceive cilantro as this “really sharp metallic, gross, soapy kind of thing.” Conversely, folks without this variation will think of the herb as a fresh, green and citrusy addition to a dish, said Knight.
“As you’re chewing cilantro, those aldehydes send this really strong signal and that can often overpower any other smells.”
While the evolutionary purpose of this phenomenon is not fully understood, the UVic researcher noted that other variations also affect our sense of smell. For instance, the OR2M7 variation is linked to asparagus. Depending on their genetic makeup, some people break down compounds in asparagus into a sulfur-containing molecule called asparagusic acid, which causes the notorious “asparagus pee” smell.
“Not everyone will actually produce the smell and not everyone can actually smell it,” she said. “Those molecules are really volatile when they get excreted in the urine and they are very detectable. Some people are metabolizing asparagus in a way that produces those really strong sulfur compounds, while others will produce very little or none at all. That difference is genetically influenced.”
While Knight herself loves cilantro, she empathizes with those whose genes hijack their perception of flavour, noting it is most definitely not a hoax as some may contend.
“Cilantro is like a scale,” she said. “Some people may only experience this really low end of what that tastes like. They can’t even imagine what it would taste like to somebody else who’s experiencing the flavour differently.”
“It’s like colours; you can’t really describe to somebody what they look like because you can’t really convey that information.”
