A few years ago I posted on the old RPF about a study showing niacinamide eeye drops can treat glaucoma and other eye conditions, by raising NAD+ levels. The study below used the same rationale and demonstrated that intranasal administration of NAD reversed anosmia (loss of sense of smell) in the experimental animals. The study used pre-formed NAD+ but given that it is unstable and that the prior study noted niacnamide as eye drops also worked, I think the same statement can be made about anosmia as well. Niacinamide dissolves very well in water (much better then NAD) and is stable (unlike NAD), in both solution and in solid form.
https://www.nature.com/articles/s12276-026-01761-9
“…In this study, we explored the therapeutic efficacy of NAD in olfactory dysfunction. Our results demonstrated that i.n. administration of NAD significantly improved olfactory function. This improvement was accompanied by enhanced neurogenesis and maturation of OSNs, as evidenced by behavioral tests and histological analyses. These findings are consistent with previous studies that highlighted the neuroprotective and neuroregenerative properties of NAD in various neurodegenerative disease models15,36.”
“…In conclusion, this study provides promising results for the potential use of NAD as a therapeutic agent to treat olfactory dysfunction by comprehensively analyzing its remarkable effects on in vitro neuronal differentiation in hOSCs and olfactory function, histology, and gene expression, using an anosmia mouse model. NAD may promote neurogenesis and maturation of OSNs and restore olfactory function by activating genes involved in synaptic transmission and neuronal survival, such as DLGAP2 and PCDH17. These results will be an important basis for exploring clinical applications of NAD.”
