Ways to Regain Sense of Smell After COVID

Ways to Regain Sense of Smell After COVID
Research specifically looking at people with COVID-related loss of smell found that smell training effectively improved their ability to detect odors. (Shutterstock)
George Citroner
1/5/2023
Updated:
3/24/2023
Among the many aftereffects of COVID-19 infection, one that has garnered much attention is the loss of smell or taste. For many people, the condition is long-term and treatment remains elusive.
Why does this happen to some people, and are there effective treatments available to restore one’s sense of smell after a COVID infection?

Loss of Smell Common With Many Viral Infections

Our senses of taste and smell work together to help us enjoy food and drink. The loss of these senses can make meals seem tasteless or bland. More importantly, we may not recognize potentially dangerous situations such as a gas leak or spoiled food.
Losing the senses of taste (ageusia) and smell (anosmia) isn’t only an early symptom of COVID-19 infection but also a well-known symptom of long COVID.
However, the condition isn’t unique to COVID.
“Loss of smell is common with numerous viral infections, and especially so in COVID,“ Dr. Jacob Teitelbaum, a board-certified internist and nationally known expert in the fields of chronic fatigue syndrome, fibromyalgia, sleep, and pain, told The Epoch Times. ”In about 95 percent, smell has returned by six months.”
In a study from New York University, researchers found that the presence of the COVID-19 virus near nerve cells in olfactory tissue stimulated an inrush of immune cells, such as microglia and T cells, to counter the infection. 
These cells release proteins called cytokines, which change genetic activity in olfactory cells, even though the virus couldn’t infect them. In other scenarios, immune cell activity dissipates quickly; but researchers theorize that COVID-related immune signaling persists in a way that impairs the activity of genes needed to build smell receptors.
Other research found why, for some people, the loss is potentially permanent.
Scientists at Duke University, with experts from Harvard University and the University of California–San Diego, used a tissue biopsy (extracted sample) to analyze olfactory epithelial cells, particularly those from COVID patients with long-term anosmia.
The findings indicate that our immune cells may continue reacting even when the threat is gone. 
Analyses revealed widespread infiltration by T cells (immune cells), which caused an inflammatory response in the nose where the nerve cells for smell are located. 
“The findings are striking,” senior author Dr. Bradley Goldstein, associate professor in Duke University’s Department of Neurobiology, said in a statement.
“It’s almost resembling a sort of autoimmune-like process in the nose.”

Steroid Nasal Spray Shows Promise

A study published in the American Journal of Otolaryngology found fluticasone (Flonase) nasal spray helped participants regain their sense of smell.
Researchers looked at 120 people experiencing anosmia due to COVID-19 and split them into two groups—one that received treatment and one that did not.
They found that smell and taste function significantly improved within one week in all patients with COVID-19 who received fluticasone nasal spray.
Teitelbaum said the nasal spray may work because viral infections can cause inflammation and swelling around the olfactory nerves. Fluticasone is an over-the-counter steroid nasal spray that reduces inflammation.
“Once the infection has been gone for a month, the OTC steroid nasal spray Flonase [used] for six to eight weeks may decrease the nasal and nerve swelling,” Teitelbaum said.
But he cautioned that this nasal spray shouldn’t be used while symptoms of active infection, such as a runny nose, are present.

Olfactory Retraining

Anosmia has been studied long before the current pandemic. A 2009 study discovered that the sense of smell could be re-sensitized in people who lost the ability to detect odors.
Researchers exposed participants to one of four odors: cloves, lemon, eucalyptus, and rose.
Patients sniffed the four intense odors twice a day for 12 weeks. They were tested for sensitivity before and after training using “Sniffin' Sticks” of various smell intensities.   
Compared to the baseline, patients who trained their olfactories experienced an increase in their sensitivity to smells, according to their Sniffin' Sticks test score. Smell sensitivity was unchanged in patients who didn’t receive the training.
Research specifically looking at people with COVID-related loss of smell found that smell training effectively improved their ability to detect odors.
“When begun early and with good compliance, olfactory training was reported to be most beneficial in enhancing olfactory function,” Teitelbaum said.

Vitamins That May Help

There are many theories as to why COVID infection causes loss of smell, but we still don’t know exactly why. 
Teitelbaum believes there’s likely a mix of several causes, including low levels of certain nutrients such as zinc.
“I give 25 to 50 mg [of zinc] a day for six months [to patients],” he said.
Zinc is critical for immune function, with the key immune system-regulating hormone thymulin being zinc-dependent. Many infections, including AIDS, deplete zinc to worsen immunity. Smell is also zinc-dependent.
Another key nutrient for smell is vitamin A. 
“The retinol form of vitamin A at doses of 2500 to 5000 units a day may, along with zinc [at] 25 to 50 mg a day, help smell over time,” Teitelbaum said. 
However, pregnant women need to be careful when taking this vitamin.
“Vitamin A will cause birth defects in pregnant women at doses over 8000 units,” Teitelbaum said. 
A case study from 2021 describes how a COVID-19 patient’s ability to smell was restored by olfactory training combined with daily doses of these B-complex vitamins:
  • 5000 IU of vitamin B1  
  • 100 mg of vitamin B6  
  • 5000 mg of vitamin B12 
The patient’s anosmia was significantly improved at 12 days and his sense of smell was recovered by day 40.  
George Citroner reports on health and medicine, covering topics that include cancer, infectious diseases, and neurodegenerative conditions. He was awarded the Media Orthopaedic Reporting Excellence (MORE) award in 2020 for a story on osteoporosis risk in men.
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