Using candy to sniff out probable cases of COVID-19
Research team develops method to screen for taste and smell loss
Scientists have proposed that using a cheap and simple product – hard candy – to screen for the loss of taste and smell in populations at risk for COVID-19 exposure may help detect probable positive cases in otherwise asymptomatic people.
The Ohio State University research team received $305,000 in National Institutes of Health funding in a competitive bid to develop easy-to-deploy strategies that can identify people who are potentially infected with SARS-CoV-2.
While symptoms like fever, chills, a cough and body aches vary widely among COVID-19 patients, an estimated 86% of people who test positive report a loss of smell, “which makes it a much better predictor, especially if it’s sudden loss,” said project co-leader Christopher Simons, associate professor of food science and technology at Ohio State.
Eight flavors of hard candies that are uniform in color will be manufactured for the test of the method’s effectiveness. Asking people to identify flavors by smelling and tasting the candies allows for sophisticated assessment of the function of two routes – via the nose and the back of the throat – by which our sense of smell helps tell us what we’re eating, Simons said.
Plus, the sweet treat is hard to resist as a scientific screening tool.
“Who doesn’t like candy? It’s an ideal stimulus because for this to work, people have to want to do it,” he said.
Simons’ lab in the College of Food, Agricultural and Environmental Sciences focuses on understanding the neural and physiological underpinnings of how we perceive food. The research team also includes taste biologist Susan Travers, professor of biosciences in the College of Dentistry, and Kai Zhao, associate professor of otolaryngology in the College of Medicine, who specializes in olfaction – the sense of smell. The new funding is a competitive revision to one of Travers’ existing NIH grants.
Simons has personal experience with COVID-19 symptoms. His entire family tested positive for SARS-CoV-2 in March after a trip to Spain before the borders closed. As his family raved about how good the Spanish food tasted, Simons was less impressed. But it wasn’t until he couldn’t detect the flavor of his cocktail back in Columbus that he realized he had lost his sense of smell – which ended up being his only symptom.
If this method is adopted as a screening strategy, it would complement existing tools for this purpose: a scratch-and-sniff card for smell and/or a one-time evaluation of the bitter medication quinine for taste, both of which are more expensive than candy (less than 5 cents for a piece of candy versus more than 50 cents per scratch-and-sniff card). The first phase of the Ohio State project is validating the use of candy against those established methods. Preliminary assessments have been promising.
“Quinine isn’t long-term. No one will sip on that every day,” Simons said. “We see factors that potentially indicate our method will be a long-term effective tool for long-term tracking of sensitivity.”
That long-term tracking occurs in the project’s second phase, when the team plans to follow about 2,800 people for 90 days. Ohio State students are the primary recruitment target for the study.
Participants will be asked to sniff and consume a piece of hard candy once per day and log into an app to report what they smell and taste – not only by identifying the flavor, but also rating its intensity. If they report a sudden drop in either sense, they’ll receive a message that they should quarantine and get a COVID-19 test.
Using candy will activate both the orthonasal (through the nose) and retronasal (through the back of the throat) sense of smell pathways that allow us to know what we’re tasting. Those two pathways give us a more nuanced sense of what we’re consuming than what the taste buds on our tongues actually “taste,” which are sweet, sour, salty, bitter and savory “flavors.”
“Theoretically, it’s possible that you could have some smell loss that’s more or less prominent in the orthonasal or retronasal condition that you would miss if you were only doing scratch and sniff for detection,” Simons said.
“With our assessment, you unwrap the candy and smell it to assess orthonasal olfaction, and pop it into your mouth to rate how strong the flavor is, assessing the retronasal component. You also assess sweetness and sourness, which is the taste component. It allows us to tackle three different aspects of flavor perception.”
Though the researchers have hypothesized that both olfactory pathways are affected by SARS-CoV-2, their first order of business is providing what the NIH is looking for: “a fairly simple, inexpensive and deployable technology to support public health,” Simons said.