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Labs & explainers · Updated 2026-10-30 · Editorial review in progress
Vitamin D deficiency and hair loss: mixed evidence, worth asking about
Also searched as: vitamin D25(OH)Dvitamin d deficiency hair loss
A case-control study of women with female pattern hair loss classed vitamin D below 20 ng/mL as deficient and 20–30 as insufficient, and its background notes conflicting results — including a New Zealand study of 296 men that found no link with male pattern alopecia.
No consistent week-by-week window is published for this, so it is not on the calculator.
The cut-offs researchers use
| Category | 25(OH) vitamin D |
|---|---|
| Deficient | Below 20 ng/mL [PubMed] |
| Insufficient | 20–30 ng/mL [PubMed] |
| Sufficient | Over 30 ng/mL [PubMed] |
For and against
| Finding | Source |
|---|---|
| An earlier study found lower vitamin D with more severe hair loss in women and called measurement essential | Cited in [PubMed] |
| A study of 296 men with male pattern alopecia found no correlation | Cited in [PubMed] |
NICE lists vitamin D deficiency among underlying causes to consider in hair loss [NICE]. We don't give dosing: ask your doctor whether a test is right for you.
Normal vs. warning signs
- Shedding that matches a known trigger
- Bone pain or muscle weakness
- Shedding without a trigger lasting more than 6 months
- Patches or smooth bald spots
What may help
- Ask your doctor about testing.
- Bring your timeline of triggers.
- Avoid high-dose supplements unless prescribed.
Related triggers
Ferritin & iron
Life eventsSeasonal shedding
MedicationsLevothyroxine changes
Life eventsCrash diet & fasting
Frequently asked questions
What vitamin D level is deficient?
Studies commonly use below 20 ng/mL as deficient and 20–30 ng/mL as insufficient.
Does low vitamin D cause hair loss?
Evidence is mixed: some studies in women found links, while a study of 296 men found no correlation.
Should I take vitamin D for hair loss?
Ask your doctor about testing first.
Sources
- PubMed Central (PMC5007917). Serum vitamin D3 level in patients with female pattern hair loss (PMC5007917)
- NICE Clinical Knowledge Summaries. Female pattern hair loss — differential diagnosis (telogen effluvium)