A possible correlation between vitamin D deficiency and loss of smell: 2 case reports

Abstract

Objective: The purpose of this report is to present 2 cases of diminished olfaction that improved with increasing serum levels of vitamin D3. Clinical Features: Both patients were under the care of medical and chiropractic physicians for various complaints. A 47-year-old hyposmic woman was diagnosed with vitamin D deficiency who incidentally noticed a progressive return of her sense of smell while taking vitamin D supplements as prescribed by her medical doctor. A 34-year-old anosmic woman noticed a direct relationship with her ability to smell and vitamin D3 supplementation. Intervention and Outcome: Treatment for the first patient consisted of vitamin D supplementation of 10 000 IU a day. Her serum D3 levels increased substantially over a period of 8 months, at which time she reported a marked improvement in her sense of smell. The second patient was prescribed 50 000 IU of vitamin D a week; and she reported an increased ability to smell, although only the strongest of odors. Conclusion: A link between hypovitaminosis D and a diminished sense of smell was noted in these 2 individuals.

Age-related Smell and Taste Impairments and Vitamin D Associations in the U.S. Adults National Health and Nutrition Examination Survey

“…In the literature, limited studies have investigated Vitamin D deficiency and its relationships with smell and showed similar findings. For example, a study of a few reported cases showed that olfactory dysfunction has subjectively been detected in adult patients with Vitamin D deficiency and it was improved with increasing serum Vitamin D [22]. Another study found that low serum (25(OH)D) concentrations were independently associated with olfactory dysfunction among Parkinson's disease patients [33].…”

“…Ample epidemiological studies showed that Vitamin D deficiency is associated with brain health including cognitive function, neuropsychiatric disorders [34] and mood regulation [7][8][9]. This stems from the fact that Vitamin D receptors are widely spread throughout the central and peripheral nervous systems and have an impact on various neurotransmitters [12,13,22,34]. Some animal studies have shown that the rat olfactory system contains numerous target sites of Vitamin D receptor [17,35], which emphasizes the unique functional importance of 1,25-dihydroxy Vitamin D3 in olfactory function [33].…”

“…Some animal studies have shown that the rat olfactory system contains numerous target sites of Vitamin D receptor [17,35], which emphasizes the unique functional importance of 1,25-dihydroxy Vitamin D3 in olfactory function [33]. Since Vitamin D functions as a neurosteroid hormone in the brain, spinal cord, and olfactory system [36], a lack of Vitamin D may lead not only to the neurological decline of the central and peripheral nervous system but also of the cranial nerves, causing a reduction in olfactory perception [22,37], which may explain the significant finding observed in the current study.…”

“…Other animal studies showed that Vitamin D influences neural stem cells and progenitor cell proliferation [19], creating various neuron types in the brain [20] and olfactory system [21]. Evidence on Vitamin D associated with the human olfactory system was recorded in one case report [22].…”

Dietary Approach for Post-COVID Treatment of Olfactory Loss

“…In a study conducted by Grant, et al [31], a key observation was the decrease in the production of proinflammatory Th1 cytokines, such as TNF-α, and IFN-γ. Likewise, a study conducted by Jeffery et al [32] noted inhibition of T cell inflammatory cytokine production, specifically, a decrease in the cells producing IFN-γ. A report by Kruse and Cambron [33] presented two cases of an increased ability to smell after intervention through vitamin D supplements.…”