Vitamin D and Alopecia Areata
Alopecia areata (AA) is an autoimmune hair loss disorder — sharply demarcated patches of complete hair loss, sometimes progressing to alopecia totalis (scalp) or universalis (whole body). Vitamin D receptors are strongly expressed in hair follicles, and deficiency correlates with disease severity and prognosis.
Deficiency and severity
A 2019 meta-analysis of 14 case-control studies (Lee) found alopecia areata patients had significantly lower mean 25(OH)D than controls (mean difference −7.6 ng/mL), and levels correlated inversely with severity of alopecia tool (SALT) score. Vitamin D receptor polymorphisms have also been associated with AA susceptibility.
Supplementation and topical trials
- Small trials of topical calcipotriol (vitamin D analogue) in AA reported regrowth in 27–60% of patients over 3 months (Kim 2012; Cerman 2015).
- Oral vitamin D repletion has been reported to help alongside topical therapy in deficient patients — trial data is limited to small series.
- No large RCT has established vitamin D as a stand-alone AA treatment.
JAK inhibitors — the field changer
Oral baricitinib (approved 2022) and ritlecitinib (approved 2023) are Janus kinase inhibitors that reversed severe alopecia areata — including alopecia totalis and universalis — in around one-third of severe patients over 6–12 months. These are the first FDA-approved systemic treatments for AA. They are the current gold-standard systemic therapy for severe cases; vitamin D is adjunctive at best.
Practical guide
- Test 25(OH)D — many AA patients are deficient.
- Correct deficiency (target ≥ 30 ng/mL) with 2,000–4,000 IU/day.
- Combine with dermatologist-directed therapy — intralesional or topical steroids for patchy disease; JAK inhibitors, contact immunotherapy, or systemic immunosuppression for extensive disease.
- See our hair loss page for the distinction between alopecia areata, telogen effluvium, and androgenetic alopecia — the vitamin D story is different for each.