Two 2023 papers, starting with a study of smell and taste disorders:

“This study investigates the impact of etiology on the epidemiologic profile, disease severity, type of treatment, and therapy outcome in smell and taste disorders.

Hyposmia has a prevalence of about 15%, while approximately 5% of the population suffers from anosmia. Multiple innervation of the taste mucosa with fibers from the seventh, ninth, and tenth cranial nerves assures robustness of the gustatory system compared to smell.

Conservative therapy employs corticosteroids, antibiotics, vitamins and and minerals as well as functional rehabilitation by olfactory training. Data regarding outcome of therapy were only available for 71 (26.3%) of patients. Only the sinunasal etiology was significantly more likely to show improvement after therapy (27.4% show improvement vs. 9.6% show no improvement).”

https://link.springer.com/article/10.1007/s00405-023-07967-1 “Characteristics of smell and taste disorders depending on etiology: a retrospective study”

This study was a little light on describing effective treatments for smell and taste problems. For example, olfactory training was said to have good therapeutic response. Looking it up, though, it seems to be whatever each practitioner feels like doing.

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A review introduced the subject of olfactory ensheathing cells:

“Olfactory ensheathing cells (OECs) are glial cells of the primary olfactory nervous system, which are composed of the olfactory nerve and outer nerve fiber layer of the olfactory bulb. The primary olfactory nervous system is unique in that it can constantly regenerate.

It is now possible to remove olfactory bulb tissue and olfactory mucosa (outermost layer and lamina propria, which belong to the central nervous system and peripheral nervous system, respectively), which also suggests the potential value of OECs therapy in central nervous system and peripheral nervous system diseases. OECs can survive and renew in the central nervous system, and have been widely used in nerve regeneration and tissue repair.

Schwann cells (SCs) form the myelin sheath of the peripheral nerve, protect and nourish neurons, and play an irreplaceable role in the repair of peripheral nerve injury. There is no transcriptional difference between OECs and SCs. OECs are highly similar to SCs, and express the biomarkers of SCs.

Functional mechanisms of OECs in the treatment of neurological diseases include neuroprotection, immune regulation, axon regeneration, improvement of nerve injury microenvironment and myelin regeneration, which also includes secreted bioactive factors. Results obtained in clinical trials are not very satisfactory, and the effectiveness of these cell-based therapies remains to be proved.”

https://www.frontiersin.org/articles/10.3389/fimmu.2023.1280186/full “Potential therapeutic effect of olfactory ensheathing cells in neurological diseases: neurodegenerative diseases and peripheral nerve injuries”

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Something interesting may have unexpectedly started with my 90-day trial of Prodrome Glia and Neuro products. Here’s an abbreviated look that omits my intermittent fasting and resistance exercise data:

Both product labels have a loading dose suggestion of 4-8 softgels (2 to 4 times the standard two-softgel dose) for 1-3 months. Two days after I started a Glia loading dose, my sense of smell, then sense of taste, were noticeably better.

I’ll guess that my primary olfactory nervous system glial cells are responding to these changes. At the beginning I thought that my peripheral nervous system Schwann cells might be affected regarding my left ulnar nerve. Since olfactory ensheathing cells are highly similar to Schwann cells, it doesn’t seem to be that much of a stretch to think that they could also be affected by my current regimen.

More testing is warranted, of course. I’ve had diminished smell and taste for decades, though. If the gardenias, roses, magnolias, honeysuckles, and other scents in past summers that had fainter scents than I remembered come across stronger, so much the better.