While losing your sense of smell or taste is a key symptom of COVID-19 infection, coronavirus isn’t the only threat to these senses. With advancing age, “almost everyone has a loss of hearing and vision, but most people also have a loss of smell — and thereby some loss of taste,” says Michael S. Benninger, M.D., professor and chair of the department of otolaryngology-head and neck surgery at the Cleveland Clinic. As he explains, the dual dulling is part of the gradual reduction of neurologic processes that happens as you get older, although how much you lose varies "in greater or lesser in part due to genetics.”
Like most parts of your body, your senses of smell and taste are also vulnerable to damage from chemicals, air pollution, illnesses, and other negative influences — all of which can accelerate the natural age-related decline. Here’s a closer look at what’s going on:
How age, allergies and medications factor in
Your sense of smell is fairly stable until age 50. From there, it starts a decline that accelerates after age 60, says Justin Turner, M.D., an associate professor of otolaryngology-head and neck surgery at Vanderbilt University Medical Center and director of the Vanderbilt Smell and Taste Center in Nashville. “Part of it is the natural aging process—over time, the olfactory epithelium undergoes numerous insults and injuries.” These can stem from upper respiratory infections, smoking, exposure to environmental toxins or head trauma.
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What’s more, people who have chronic nasal and sinus problems — including allergies, nasal polyps, or chronic sinus inflammation — can have more severe and earlier impairment in their sense of smell, Benninger says. And some neurodegenerative disorders, such as Parkinson’s and Alzheimer’s, are associated with a reduced ability to smell, notes Alan Hirsch, M.D., neurological director of the Smell & Taste Treatment and Research Foundation in Chicago.
Taking certain medications — like some antidepressants, tranquilizers, antibiotics, antihistamines, anti-hypertensive, and anti-cholinergic drugs — can also take a toll. And deficiencies in various nutrients, including vitamin B-12 and vitamin D, are associated with olfactory dysfunction, Turner notes. In fact, a study published in the 2020 issue of the journal Nutrients found that adults ages 40 and older who had a vitamin D deficiency were 39 percent more likely to have smell impairment.
The potential consequences extend beyond not being able to smell the roses. “A major concern with the loss of smell is safety,” Benninger says. “We use our noses to detect things like fire before we can see it and spoiled food.” That’s why it’s essential for people with loss of smell to have fully functioning smoke and carbon monoxide detectors and to check the expiration dates on food labels, Turner says.
How taste fades and how it may affect health
With a decline in your sense of smell often comes a decreased ability to taste. That’s because “90 percent of taste is really due to smell,” Hirsch says. “If you eat chocolate while holding your nose, it tastes like chalk.” While less common, having an oral infection (such as gingivitis or periodontal disease), dry mouth, diabetes or high blood pressure can compromise your sense of taste on its own, Hirsch says. “And head trauma can cause taste loss without smell loss or vice versa or both.”
Not only do people with taste or smell dysfunction get less enjoyment out of eating, they can also face health issues, Turner says. “As people get older, a lot of those folks can have nutritional deficiencies and weight loss.” In fact, a study in a 2016 issue of the European Journal of Nutrition found that older women with moderate to severe olfactory impairment compared to those without impairment had a significantly poorer diet quality. More recently, a study in a 2021 issue of The Journal of Nutrition found that older adults with diminished taste function had poorer diet quality compared to those with normal taste function.
Sharpening these senses
To protect your senses of smell and taste from further damage, avoid exposure to cigarette smoke and vaping as well as chemicals and harsh cleaning products. You may also be able to improve your nose's receptor sites by giving yourself olfactory training (a.k.a. smell therapy): Take a handful of scents from everyday life or essential oils (such as anise, ginger, lavender, lemon, sandalwood, and others) and smell them each deeply for around four minutes twice a day. Doing so may also help train your brain to associate certain sensations with particular smells, Benninger says.
Recovering smell and taste after COVID-19
In the last two years, COVID-19 infection has become notorious for causing loss of smell and taste. Indeed, the percentage of people who experience dysfunction with these senses is much higher with this virus than with other viral infections, experts say. A review of studies in the August 2020 issue of the journal Mayo Clinic Proceedings found that 41 percent of the more than 8,000 participants with confirmed cases of COVID-19 experienced olfactory dysfunction, and 38 percent had taste dysfunction. After people recover from COVID-19, most regain their sense of smell approximately six weeks after infection, Turner says. For those who do not, doctors often prescribe olfactory training as well as systemic or topical steroids, to reduce any inflammation that could be contributing to smell loss.
Stacey Colino is an award-winning writer, specializing in health, psychology, and science. Her work has appeared in The Washington Post, U.S. News & World Report, Prevention, Newsweek, Parade, and many other national magazines.