Show 1422: The Science of Smell

This week, our guests take two different approaches to the sense of smell. We talk with a surgeon who treats people having difficulties with that sense. In addition, a nurse describes utilizing the sense of smell for aromatherapy in integrative healing. Learn about the fascinating science of smell.

You could listen through your local public radio station or get the live stream at 7 am EDT on your computer or smart phone (wunc.org). Here is a link so you can find which stations carry our broadcast. If you can’t listen to the broadcast, you may wish to hear the podcast later. You can subscribe through your favorite podcast provider, download the mp3 using the link at the bottom of the page, or listen to the stream on this post starting on March 17, 2025.

The Science of Smell:

Of all our senses, the sense of smell often gets short shrift. Aside from Marcel Proust’s evocative description of the link between odor and memory, we don’t think much about smell. Scientists have discovered, however, that much of our social interaction relies on olfaction at a subconscious level. It plays a largely unconscious role in our choice of mates as well as in the timing of sexual activity. It is also important for the bonding between mothers and their infants. Consequently, the sense of smell is crucial for the survival of our species, even when we aren’t paying attention.

Losing our sense of smell can be devastating, as too many people learned by experience during the COVID-19 pandemic. Not only did they miss out on pleasant aromas like fresh-brewed coffee or newly mown grass, but they also were at a disadvantage in detecting if there might be gas leaking in the kitchen or a fire smoldering somewhere in the house.

Although some of those who lost their sense of smell during an acute infection subsequently regained it, others did not. Too many people are still suffering from anosmia. Is there anything that can be done to help them?

Regenerating Nerves in the Nose:

Many viruses can cause inflammation in nasal tissue and potentially damage the sense of smell. During COVID-19, the SARS-CoV-2 virus attacked ACE receptors on cells in the olfactory epithelium of the nose. These cells are not the nerve cells themselves, but support cells (called, if you must know, sustentacular cells). Fortunately, these cells can regenerate, although it takes time.

The Science of Smell Recovery–Olfactory Training:

The first step in recovering the sense of smell is olfactory training. It could be considered something like physical therapy for the nose. In this structured smelling protocol, people are exposed to one of four distinctive aromas from essential oils: lemon, rose, eucalyptus or clove. As they attempt to discern the scent, they remember how they used to experience those odors. As part of the protocol, they also irrigate their nasal passages with high-dose steroids in saline solution (International Forum of Allergy & Rhinology, Sep. 2018).  Over many months, this concerted effort is able to help 30 to 50 percent of patients recover their sense of smell to a satisfactory degree.

The Science of Smell Recovery–Platelet-Rich Plasma:

To help people who are not successful enough with olfactory training, Dr. Zara Patel has pioneered the use of platelet-rich plasma. PRP injections have been used to help athletes recover from injury. Since it can be helpful in situations where inflammation is high, she tried PRP injections for people with difficulty smelling. A randomized controlled trial showed that the injection is safe and may be effective in helping people recover their sense of smell after COVID-19 (International Forum of Allergy & Rhinology, June 2023).  She hopes to conduct a larger study that would be more conclusive.

Harnessing the Sense of Smell with Aromatherapy:

Dr. Patel was careful to point out the distinction between olfactory training, based on the science of smell, and aromatherapy. Our other guest, an integrative care nurse, utilizes aromatherapy to help people in post-anesthesia care units. There is some evidence, for example, that the aroma of lavender essential oil can help anxious patients relax and get to sleep, but better studies are necessary (Phytomedicine, Dec. 2019).

Plants use the volatile compounds in their essential oils for communication. In addition, some terpenes in juniper or pine have antiviral activity, while components in clary sage or bergamot have antifungal properties. Nurses in some cancer hospitals utilize aromatherapy to help patients overcome nausea and pain associated with chemotherapy. This is an area of the science of smell in which our guest Kathy Fritze has special expertise.

This Week’s Guests:

Zara M. Patel, MD, is Professor of Otolaryngology-Head and Neck Surgery at the Stanford School of Medicine. Her website is https://profiles.stanford.edu/zara-patel

Zara Patel, MD, Stanford School of Medicine

Kathy Fritze, RN, BSN, is a holistic and integrative care nurse in the Wellness & Support Center at the University of Maryland St. Joseph Medical Center.

Kathryn Fritze RN, BSN

Listen to the Podcast:

The podcast of this program will be available Monday, March 17, 2025, after broadcast on March 15. You can stream the show from this site and download the podcast for free. In addition to what you heard in the broadcast, the podcast includes additional information on why people sometimes detect strange odors that others don’t perceive. We also discuss people who have strong reactions to odors in perfume or detergent, such that they become physically ill when they smell them.