What vitamin deficiencies are associated with alopecia?

Vitamin Deficiencies to Check in Alopecia

In patients presenting with alopecia, check serum vitamin D (25-hydroxyvitamin D), zinc, and red blood cell (RBC) folate levels, as these are the micronutrients most consistently associated with hair loss. 1

Primary Screening Recommendations

Vitamin D (Most Strongly Supported)

• Check serum 25-hydroxyvitamin D levels in all alopecia patients, particularly those with alopecia areata 1
• Multiple case-control studies demonstrate significantly lower vitamin D levels in alopecia areata patients (83.3% deficiency rate) compared to controls (23.3% deficiency rate) 1
• Vitamin D levels inversely correlate with disease severity—more severe alopecia associates with lower vitamin D concentrations 1, 2
• Vitamin D deficiency is also documented in androgenetic alopecia, with 86% of premature male pattern baldness cases showing deficiency 3
• Important caveat: One large prospective study of 55,929 women found no association between vitamin D intake and incident alopecia areata, suggesting reverse causation may explain some cross-sectional findings 1

Zinc

• Measure serum zinc levels, as zinc deficiency associates with alopecia areata 1
• Zinc serves as a cofactor for over 70 enzymes essential for hair follicle function 4
• Normal plasma zinc levels are 100 ± 12 mcg/100 mL 4
• Combined zinc supplementation (with biotin and topical therapy) showed 33.3% complete regrowth versus 0% in controls 1

Folate (Vitamin B9)

• Check RBC folate rather than serum folate for accurate assessment of long-term folate stores 1
• RBC folate levels are lower in alopecia areata patients and correlate negatively with disease severity (SALT score) 1
• Serum folate fluctuates with acute dietary intake and is less reliable 1

Secondary Considerations

Iron/Ferritin

• Evidence is conflicting and gender-dependent for iron deficiency in alopecia 1
• Lower ferritin levels found primarily in female patients with alopecia areata and androgenetic alopecia, but not consistently in males 1
• Current evidence is insufficient to recommend routine iron screening in all alopecia patients 1
• Consider checking ferritin specifically in women with hair loss 1

Vitamin B12

• Not routinely recommended as multiple case-control studies found no differences in B12 levels between alopecia areata patients and controls 1
• Only case reports (not controlled studies) link B12 deficiency to alopecia areata 1
• Consider checking only if pernicious anemia is suspected clinically 1

Biotin

• Biotin deficiency causes hair loss only in rare cases of genetic abnormalities or excessive raw egg consumption 1
• Insufficient evidence to recommend routine biotin screening 1

Other Micronutrients

• Vitamin E, beta-carotene, copper, magnesium, and selenium have insufficient or conflicting evidence to warrant routine screening 1

Clinical Algorithm

For any patient presenting with alopecia:

1. Always check: Serum 25-hydroxyvitamin D 1, 2
2. Always check: Serum zinc 1, 4
3. Always check: RBC folate (not serum folate) 1
4. Check in women only: Serum ferritin 1
5. Check if clinically indicated: Vitamin B12 (only if pernicious anemia suspected) 1

Important Caveats

• Most evidence comes from small retrospective case-control studies (<100 patients), limiting generalizability 1
• Reverse causation is possible—hair loss may lead to lifestyle changes (sun avoidance, dietary changes) that affect micronutrient levels 1
• Serum micronutrient levels may not accurately reflect tissue bioavailability; ferritin can be elevated by inflammation, infection, or malignancy 1
• Few randomized controlled trials exist for micronutrient supplementation in alopecia treatment 1
• One pediatric case report demonstrated complete remission of alopecia areata within 5 months using vitamin D, zinc, and vitamin A supplementation combined with dietary modification 5