COVID-19 has impacted millions globally, with a notable symptom for many being a change in their sense of taste and smell. This alteration can significantly affect daily life. Understanding these sensory changes and the journey to recovery remains important for those affected.
Understanding the Alteration of Taste and Smell
COVID-19 can affect chemosensory perception in several ways, extending beyond simple loss. Anosmia is the complete loss of smell, and hyposmia indicates a reduced ability to smell. Similarly, ageusia is the complete absence of taste, while hypogeusia is a diminished sense of taste. Dysgeusia describes a distorted sense of taste, where foods might taste metallic, bland, sweet, or salty in unusual ways.
Parosmia involves distorted smells, often making pleasant odors smell foul, like smoke or rotten meat. Phantosmia is the perception of phantom smells not actually present. The close relationship between taste and smell means disruptions in one often affect the other. Approximately 80% of what we perceive as taste is influenced by smell, meaning a compromised sense of smell can make food seem bland or tasteless.
The Underlying Mechanisms
The SARS-CoV-2 virus affects taste and smell by impacting supporting cells, not directly damaging neurons. Specifically, the virus targets sustentacular cells that support olfactory neurons in the nose. These cells are rich in ACE2 receptors and TMPRSS2 enzymes, which the virus uses to enter. Once infected, these support cells become targets for the immune system, leading to inflammation.
This inflammatory response appears to be a primary driver of smell loss, rather than direct viral damage to the olfactory sensory neurons themselves. The inflammation can disrupt the function of these supporting cells, preventing olfactory nerve signals from reaching the brain effectively. While the exact mechanisms are still being explored, the focus is on how this cellular disruption and subsequent inflammation lead to the varied sensory changes observed in COVID-19 patients.
Navigating Recovery
The timeline for recovering taste and smell after COVID-19 varies significantly among individuals. Many people experience improvement within a few weeks; for instance, around 90% of those affected may see improvement within four weeks, and 95% might recover within six months. However, some individuals, about 10%, may experience a loss of smell that lasts for eight weeks or even several months.
For a small subset, these changes can persist for longer, becoming a component of long COVID. Recovery often happens gradually, and individuals may notice their senses slowly returning over time. While the majority do regain their senses, a minority might experience incomplete recovery or persistent distortions like parosmia, which typically appears two to three months after the initial infection.
Strategies for Coping
Coping with altered taste and smell involves several practical approaches to improve the eating experience and stimulate sensory recovery.
- Focus on the texture, temperature, and visual appeal of food to enhance enjoyment.
- Experiment with different seasonings, such as herbs, spices, lemon juice, or vinegar, to introduce detectable flavors.
- Consider cold or room-temperature foods, which might be more palatable for some individuals.
- If a metallic taste is present, use plastic utensils instead of metal ones.
Smell training is a recommended practice to help re-engage and retrain the olfactory system. This involves regularly smelling a set of strong, distinct scents, such as rose, lemon, eucalyptus, and clove, typically twice a day for several months. During smell training, concentrating on memories associated with each scent can further stimulate neural pathways. Maintaining good oral hygiene, including regular brushing and rinsing, is also important for overall oral health and can indirectly support sensory recovery.