After Losing His Sense of Smell from COVID-19, an Italian Gastronomer Discovered How to Get It Back
On March 17, 2020, Michele Crippa, a super-taster—somebody who experiences taste more strongly than others—and professor of gastronomy at multiple Italian universities, made himself a cup of coffee. It was 9:40 a.m. when he poured himself a cup and brought it under his nose. But instead of being greeted by the warm smell of roasted coffee beans, he felt a "cosmic void"—he couldn't smell anything. That's when he speculated that he had contracted COVID-19.
Crippa was experiencing anosmia, the loss or impairment of one's sense of smell, and ageusia, the loss or impairment of taste. But he was not alone: back in 2020, around 41% of patients affected by COVID-19 were reporting these symptoms, per a review published in Mayo Clinic Proceedings. Moreover, according to a 2022 meta-analysis in BMJ, about 5% of individuals who have been infected with COVID-19 could develop persistent smell or taste dysfunction. After a few months, Crippa's ageusia and other COVID-19 symptoms subsided. And while his sense of smell also came back, it was in an unexpected way: everything around him smelled like cooked cabbage and wet ashtray.
Every morning, before opening his eyes, Crippa prayed not to smell that awful scent. But all he could smell was wet cigarette ash. Eventually, in December 2020, he entered a new phase, called parosmia. He began sensing some odors, but they were all distorted: lemons and oranges smelled like soap, peaches like basil, coffee like sewage, and vanilla like vomit.
According to a 2020 study published in Chemical Senses, about 10% of those who experienced smell loss because of COVID-19 still suffered from different stages of smell distortions after six months.
Historically there have been treatments available for those experiencing issues with their sense of smell. Scientists and doctors around the world began proposing various remedies that ranged from essential oil therapy to getting hit on the head by a chiropractor, yet they often didn't help or even exacerbated the problem. But there might be a silver lining for those suffering from this condition: according to Federica Genovese, a neuroscientist at Monell Chemical Senses Center in Philadelphia who's studying the chemosensory effects of COVID-19, olfactory neurons are some of the few groups of neurons capable of cyclically regenerating throughout our lives. Simply put, this should cause the sense of smell to return with time. But when intense inflammation—like that caused by COVID-19—destroys these neurons, the regeneration process can go wrong, causing unexpected olfactory distortions.
Searching for Lost Scents
Crippa, who had built his life around the use of his nose, took an unusual approach to guide his olfactory neuron regeneration, something nobody had tried before. He went a bit further than smelling flasks of distilled scents to awaken his olfactory bulbs.
He tried to harness his memory of smells to reactivate his olfactory system. He even created a class on how to use sensory analysis techniques to awaken smell memories for others suffering from loss of smell caused by COVID-19. What if the exercise of thinking about those smell-related memories could help correct some of the distortions experienced by people around the world?
Since September 3, 2021, when Crippa started training on himself and vanilla was an unbearable scent, his method has helped him and others to partially recover. "I can now smell vanilla," he said victoriously.
Crippa's students have been experiencing slow improvements as well, and his training method has attracted attention from around the world, including from scientists and researchers at Harvard Medical School and the Monell Chemical Senses Center.
"Close your eyes and think of the smell of coffee," Crippa said, then paused, waiting for me to evoke a memory linked to that smell. "Can you think of it?" I nodded. "That's something," he said with a smile.
On November 6, 2021, Crippa invited me to attend one of his Smell Education classes in Muggiò, on the outskirts of Milan. He welcomed me in his father's architecture office, in the basement of his family's house. On the weekends, in between folders of building projects and large-scale printers, a corner of the space hosts smell-seekers who have been contacting Crippa since international press coverage spotlighted his work.
"What we will do is qualitative work, not quantitative work," Crippa said as we waited for attendees to show up for his class. The goal of the course is not to enhance the way people smell but to educate them and hopefully give them tools to teach their noses how to perceive in the right way again.
We hardly notice the work of our olfactory system, but it is active from the moment we are born: it functions as a danger detector by alerting the brain about a nearby fire or a gas leak; it works as a toxin discriminator by telling us not to drink spoiled milk or eat rotten meat; it acts as a pleasure trigger by allowing us to enjoy a morning coffee or a warm slice of pizza. The sense of smell has a crucial role in our lives, something that many people experiencing COVID-19 long-hauls have had the misfortune of discovering in the past two years.
Usually, the olfactory sensory neurons in our noses detect odor molecules from food or other things around us. The neurons then send a signal to our brain. Immediately afterward, the brain decodes the signal and tells us that what we are smelling is, for example, coffee. Those who have problems with their sense of smell because of long COVID-19 suffered from inflammation that caused neuronal damage to the cells that maintain the health of olfactory neurons.
Genovese told me that smell works like a keyboard wired to a computer. Each scent clicks some keys, the olfactory neurons, that are kept together by the plastic keyboard, which is the olfactory system made of supporting cells. The messages written on the keyboard are then sent through a wire (a neuron) to the brain's limbic area and then to the thalamus, which functions as a computer.
"If we destroy the plastic that keeps together a keyboard, the keys get disassembled," Genovese said. "Some will get lost, others will get disconnected, and we won't be able to introduce inputs in our computer." And this is what COVID-19 does: it affects the supporting cells of the olfactory neurons and leads to the loss of olfactory function. Later, according to Genovese, when the regeneration begins, neurons try to reconnect to the olfactory bulb all at the same time, but the crowding increases the possibility of errors and causes the perception of distorted smells (parosmia).
Helping Others Regain Theirs
At around 10:30 a.m. on that November day, Luca Vergnanini and Simona Iannace entered Crippa's basement for his class. Crippa greeted them and asked them to take a seat in the red chairs at opposite ends of a white table, with a separator placed to create a sort of cubicle. An hourglass filled with red sand stood between the two, waiting to be flipped. To put them at ease, Crippa began his class by sharing his own experience with smell distortion. Then, he asked Vergnanini and Iannace, who had been struggling with post-COVID parosmia for months, to do the same.
"It's impossible to forget about my condition because we eat at least three times a day," Iannace said. "And the problem is that others do not understand what you are going through," Vergnanini added. Every Sunday, when he has lunch with his parents, they routinely ask him: "Isn't this very good? Have you smelled that great perfume?"
"But when I eat, I only feel like I am eating cardboard," Vergnanini said dejectedly, remembering the time when he used to love eating chocolate.
Not a doctor, nor a therapist, Crippa made sure they understood his role as an educator. He was aware of the psychological strain that people in his situation suffered. "I am not a psychologist, but it happened that people burst into tears during the class," Crippa said.
According to Valentina Parma, a psychologist at the Monell Chemical Senses Center, and chair of the Global Consortium for Chemosensory Research, having problems with the sense of smell can increase the risk of depression. A 2021 study published in the Journal of Affective Disorders Reports spotlighted how Reddit users affected by COVID-19-related smell and/or taste loss experienced a higher rate of suicidal thoughts than other people who had COVID-19 but didn't experience sensory loss.
"This study amazed me because it showed how smell and taste are functions we would never expect to lose, and when we do lose them, our vision of the world changes," Parma said.
Vergnanini showed signs of tiredness, mixed with hints of resignation, while describing all the therapies he had attempted through the past year. Nothing worked, but a lot of money was spent, he said.
For his classes, Crippa borrowed a tool supported by years of statistical analysis called a Sensory Box. This approach was created by Luigi Odello, the president of the Tasters Study Center, a cooperative created in 2013 that studies sensory analysis and trains professional tasters. The box contains 20 numbered flasks filled with common aromas, like truffle and honey. The Center's research identified these scents as widely recognized by the Italian population, and they include specific data about the percentages of how and what people perceived, subdivided into ages and groups.
"Sensory analysis is the description of the measurement of what you perceive. It's a mix of techniques and methods that make objective something that for nature is subjective," Odello said.
Novella Bagna, a professor of sensory analysis and the founder of Good Senses, a sensory analysis consulting firm, was the one who suggested Crippa try smell training, something many doctors worldwide were recommending for cases like this, per a 2021 publication in Medicine. But to help Crippa, she added a booklet to the Sensory Box that described specific everyday situations or memories with the scent that an average Italian person might relate to.
According to Genovese, from the moment we are born, our brain registers every smell we stumble upon, and to make it stick more and codify it, our brain associates it with objects, memories and emotions: the time we fell in love, that time we took a nice trip and the memory of that much-loved relative, are all linked to smell memories. And, according to Crippa, each culture shares a specific set of those odors.
Lemon Granita in Sicily
The class went like this: First, Crippa gave the numbered flasks to Vergnanini and Iannace, asking them to open and smell each for three seconds and then write down what they smelled or what the smell reminded them of. He flipped the hourglass and whispered to me that this was the most challenging exercise, but it would tell him how much they could not perceive, and most importantly, it would stress them to use their nose.
They both got a few smells right, left a few blank and filled in with memories for others. Vergnanini wrote "grass" next to what was supposed to be the mushroom smell and "urine" for honey. It was not that Vergnanini was smelling urine, but his brain was incorrectly decoding the signal for honey. Iannace filled in "breakfast with friends" for the coffee smell.
Then, Crippa distributed a sheet with the names of the 20 flasks. He flipped the hourglass and asked them to smell again and place the correct number of the flask next to the food they thought the smell belonged to. If they couldn't guess the right one, Crippa would tell them what that smell related to: "Bring your mind to the shortcrust pastry, custard and cakes. You are making shortcrust pastry. How do you make it? Bring your mind to your childhood, school, games, candies, moments of joy and happiness. This perfume evokes the world of pastry and cakes," Crippa read out loud from the sensory booklet's page connected to that smell.
"Ahh, wait …" Iannace said. "I think it's butter." Vergnanini looked flabbergasted when instead of urine, he could recognize something that reminded him of the natural perfume of honey.
"By seeing the name of the product, for synesthesia [when one sense stimulates other parts of the body], there is a combination of vision, smell and hearing stimulus," Crippa said. According to Genovese, we usually associate words with images, but when it comes to smell we need to actively seek for it, for example by undertaking olfactory training.
Finally, after the students' senses had been awakened, Crippa got rid of the sensory box and substituted each scent with natural products. He doesn't want people to train only on one specific molecule, like the limonene molecule for lemon, because genuine products have a complex variety of odor molecules that compose their scent. Otherwise, if people identify one molecule as the scent of a lemon, they might recognize all citrus as that lemon molecule.
"Look into that memory of eating a lemon granita in Sicily with your grandparents," he said. He explained how to find fresh products, close them in airtight jars and concentrate on doing this training every day, week after week, to train to reestablish that lost connection from the inside out.
"And then, with time, you might find lemon again," he said.
The Connection Between Scent and Memory
According to Stella Lee, a rhinologist at Harvard Medical School in Boston, what Crippa is doing is quite sophisticated. "What's really interesting is how he's looking at the interaction between smell and memory, and that's what he's using to help people to regain a smell," said Lee.
The idea that recalling memories connected to smell could potentially help regenerate the neural networks disrupted by the virus is a topic Lee has been working on, thanks to a research grant from the Alzheimer's Disease Research Centers. The scientific community acknowledges that smell and memory are closely connected, per a 2022 article published in Nature. Patients who have neurodegenerative disorders like Parkinson's disease or Alzheimer's may have an impairment in their sense of smell. Lee said she is looking forward to studying Crippa's data because she believes that gastronomic sciences could help in solving this medical anomaly.
That said, there is currently little scientific explanation for what Crippa is experimenting with. While excited about Crippa's work, all the researchers I talked to warned me that time would be needed to understand whether the improvements are related to Crippa's method or to the natural healing of the olfactory system.
A Sign of Hope
"The discourse of recalling memories can be valid, yes, but [only] up to a certain point because we know that we have physical damage," Genovese said. But she believes that training and stimulating the olfactory neurons might help recover the lost smells. With her team, she's looking forward to giving a more scientific context to Crippa's trials.
Crippa is openly sharing his data with researchers worldwide, hoping that others around the world will develop sensory boxes linked to their specific cultures. As he explained, Americans might not recognize the smell of violet, porcini mushrooms or licorice, but will most likely perceive scents like cinnamon or other memories connected to cultural smell cornerstones, like those filling a grandmother's kitchen for Thanksgiving dinner.
Crippa's class is not the final solution for what countless people are suffering from; he and the researchers know this well. But it is a novel approach.
"I noticed that something has happened," said Greta Seregno, a 29-year-old who attended Crippa's first class on October 15, 2021. "My nose has done its homework and is able to perceive many more smells than 30 days ago."
In March 2022, in collaboration with hospitals and universities, Crippa scaled up his work to meet the increasing requests for help and opened two medical centers, Feel Good–Neurochemistry of Wellness, in Milan and Barcelona. Patients there follow a three-month course and are supported by a physician, a neuropsychologist, a smell trainer and an organization and nutrition coach.
While there's no guarantee that everyone who does olfactory training will regain their sense of smell, trying Crippa's at-home training can be a break in the clouds for some.
Crippa himself, even after a year and a half of training, has not healed completely, but he said he'll keep trying morning after morning, lemon rind after vanilla bean. Besides, according to 2022 research published in JAMA Otolaryngology–Head & Neck Surgery, almost 90% of people who reported dysfunctions in their sense of smell or taste due to COVID-19 fully regained normal function within two years.
"Take care of this sense...because losing it means losing memories, not making new ones and losing a part of oneself," Crippa said.
How You Can Work on Your Own Sense of Smell at Home
Choose Your Stimuli
You can construct your smell kit at home by gathering natural products widely available and recognized by your culture. When choosing, make sure that the products are also linked to your sphere of personal experiences and memories. You will have to look into five aromatic families: flowers, fruits, spices, toasted and vegetables. In the flower family, you can pick iconic flowers that are easily recognizable, such as roses and lavender. In the family of fruits, you can choose fruits native to your territory, but you can also pick the globally recognized lemon, apple, pear and banana. In the family of spices, you can choose spices original to your gastronomic culture, like cinnamon for Americans, licorice for Italians and cardamom for Indians. In the family of vegetables, pick products that give a fresh sensation like mint or pine. In the family of toasted, use aromas like ground coffee and chocolate.
Use a Manageable Number of Products
When you have to decide how many products to use, it all comes down to organization and the availability of the products. Try using two products per aromatic family, so you will have about 10 products in total. But don't overdo it by adding too many, because that will make logistics hard, and the training will become time-consuming: it's easier to train twice a day for seven minutes than for a half-hour at a time.
Prepare the Products
Choose small boxes or jars, because you will have to preserve some products in the fridge. Make sure to make them airtight by using plastic wrap, a tight-fitting lid or a cork. By preserving them correctly, you'll be able to use them for more sessions.
Follow these Steps to Train Your Nose
Crippa recommends doing the smell training every morning after waking up (with your clean and rested nose after a night's rest) and at night before going to sleep.
Uncork the jar and smell the product for 3 to 6 seconds. This is when you will stimulate your olfactory perception by evoking words, aromas and memories linked to the products you have in the jars. Leave at least 45 seconds between smelling one product and the next.
When you smell the product, look at it and take notes in a notebook:
- Seek specific words that can help describe that product, and note them down.
- Look for memories connected to that product, and write them down: for example, when you smell spices like cinnamon, seek memories linked to a Thanksgiving dinner or a baking session with a friend.
- Register how much you can perceive the smell quantitatively and qualitatively, ranking it from 1 (very low perception) to 10 (excellent perception). When you begin the training, you might smell a 1 or 2, but maybe, after some training, that smell will become a 4, and so on.
Repeat this simple training every day, in the morning and at night. By noting down each training, you will be able to go back and check eventual improvements. The more consistent you are, the more likely you will witness some results and progress.