Vitamin D is an essential nutrient involved in many body functions, including supporting hair growth.
Growing evidence indicates that VDR plays a crucial role in normal hair cycling. As vitamin D helps hair follicles grow, low vitamin D levels can affect hair growth. Vitamin D deficiency may cause hair loss in some people.
A new systematic review and meta-analysis investigated whether patients with alopecia are more likely to have vitamin D deficiency (VDD) or lower vitamin D levels than controls and the prevalence of VDD among patients with certain alopecia disorders.
Alopecia can be classified into non-scarring and scarring types. Non-scarring alopecias are characterized by hair loss without permanent damage to hair follicles, while scarring alopecias result in permanent destruction of hair follicles due to inflammation and fibrosis.
The vitamin D receptor (VDR) plays a crucial role in hair follicle cycling by regulating hair growth phases, particularly the transition from the anagen phase to the catagen phase.
VDR also modulates the immune response in alopecia by interacting with key immune cells, such as T and B lymphocytes, macrophages, and dendritic cells, which are involved in the pathogenesis of autoimmune disorders.
The analysis found that both non-immune-mediated alopecias and immune-mediated hair disorders may be associated with VDD.
Vitamin D deficiency was prevalent among patients with various alopecia disorders, especially with alopecia areata and frontal fibrosing alopecia, who demonstrated a higher likelihood of VDD and lower vitamin D levels compared to controls.
The role of vitamin D as an immunomodulator is particularly relevant in alopecia areata, in which autoimmune mechanisms are hypothesized to play a pivotal role. Insufficient vitamin D levels may contribute to dysregulation of the immune response in alopecia areata, potentially resulting in an autoimmune attack on hair follicles.
Interestingly, studies conducted in Eastern nations reported a higher prevalence of vitamin D deficiency, likelihood, and reduction than in Western nations.
The authors concluded that the study’s results should be interpreted with caution due to the highly heterogeneous study population and setting of the included studies and the fact that serum vitamin D levels can be affected by a variety of factors, such as geographic characteristics, ethnicity, and skin tone.
Yongpisarn T, Tejapira K, Thadanipon K and Suchonwanit P (2024) Vitamin D deficiency in non-scarring and scarring alopecias: a systematic review and meta-analysis. Front. Nutr. 11:1479337. doi: 10.3389/fnut.2024.1479337
