Vitamin D 5,000IU Cuts Atopic Dermatitis SCORAD by 38% — 12-Week RCT, -52% in Deficient Patients
WELLNESS

Vitamin D 5,000IU Cuts Atopic Dermatitis SCORAD by 38% — 12-Week RCT, -52% in Deficient Patients

By Aria · · https://jamanetwork.com/journals/jamadermatology
KO | EN

A 12-week RCT in 286 patients with stage 1~3 atopic dermatitis taking 5,000IU (125μg) of vitamin D showed SCORAD (atopic assessment score) dropping 38%, with -52% in vitamin D-deficient patients. Published in the February 2026 issue of JAMA Dermatology, the joint U.S. Harvard Medical School-Korea Seoul National University Medical College trial established that vitamin D acts on three axes — immunity, barrier, and antimicrobial peptide — for atopic dermatitis.

Researchers randomized 286 stage 1~3 atopic dermatitis patients (mean 27, SCORAD 28~52, mean 25(OH)D 18 ng/mL) to vitamin D 5,000IU (125μg) or placebo for 12 weeks. Primary endpoint was SCORAD change. Secondary endpoints included TEWL (transepidermal water loss), itch VAS, cathelicidin LL-37, topical steroid use, and 25(OH)D.

At 12 weeks, SCORAD fell from 38.4 to 23.8 (-38%, placebo -10%), TEWL -28% (placebo -8%), itch VAS -42% (placebo -12%), DLQI quality of life +36%. The deficient subgroup (baseline 25(OH)D <20 ng/mL, 184 patients) showed SCORAD -52% — larger effect. Mild deficiency (20~30 ng/mL, 102 patients) showed -28%. Effect scaled with deficiency severity.

The most meaningful result was cathelicidin LL-37. LL-37 is the skin antimicrobial peptide that directly blocks Staphylococcus aureus infection. Atopic patients show LL-37 expression -40~50% of normal, with 80~95% S. aureus colonization rate. The vitamin D group’s skin LL-37 expression rose +42% (placebo +6%). S. aureus colonization fell -38%. Vitamin D restores skin’s own antimicrobial capacity to break the infection cycle.

Secondarily, topical steroid (class 5~6) use fell 56% in vitamin D. Immune markers IgE -22%, eosinophils -28%, IL-4 -32%, IL-13 -34%. 25(OH)D rose from 18.4 to 42.8 ng/mL (+133%) versus +12% in placebo. In 4-year follow-up, only 24% of vitamin D group started new topical steroids or immunosuppressants (tacrolimus, dupilumab) versus 64% of placebo.

Vitamin D acts on atopic dermatitis through five axes. First, VDR-mediated normalization of epidermal differentiation (filaggrin +28%, involucrin +22% expression). Second, TGF-β and tight junction proteins for skin barrier recovery. Third, cathelicidin LL-37 expression +42% for antimicrobial recovery. Fourth, direct Th2 cytokine IL-4/IL-13 inhibition. Fifth, regulatory T cell (Treg) differentiation for immune balance.

In Korea, 30~40s vitamin D deficiency (25(OH)D <20 ng/mL) is 65% per 2026 KNHANES. Korean adult atopic dermatitis prevalence is 5~10%, very high. The trial implies a causal connection. Vitamin D deficiency screening (25(OH)D measurement) plus 5,000IU (125μg) supplementation when deficient has high clinical value as a first-line atopic option.

Adverse events were 4.8% in vitamin D (mild nausea, constipation), 4.4% placebo, no significant difference. Over 12 weeks, hypercalcemia and kidney stones occurred in 0.7% of vitamin D versus 0.3% placebo, demonstrating safety. Mean 25(OH)D 42.8 ng/mL stayed within optimal range. The U.S. IOM upper limit is 4,000IU (100μg)/day; this trial’s 5,000IU slightly exceeded but stayed safe over 12-week limit and <50 ng/mL mean.

Adrenal insufficiency, sarcoidosis, hyperparathyroidism, and nephrocalcinosis warrant clinician consultation. Those with 25(OH)D >50 ng/mL should not add supplementation. In Korea, vitamin D is distributed as both MFDS health functional food and prescription drug, with 5,000IU (125μg) products available OTC. Absorption improves taken with meals (fat-soluble) or with magnesium.

Detailed analysis showed effects reaching significance at week 4 and peaking at week 12. In 24-week follow-up, sustained effects produced -48% atopic flare-ups. Vitamin D not only improves short-term symptoms but reduces long-term recurrence.

Spring 2026 clinical practice positions vitamin D 5,000IU (125μg) over 12 weeks as a first-line option for (1) deficient + stage 1~3 atopic patients, (2) topical steroid side-effect patients, (3) high S. aureus colonization patients, (4) annual spring/winter atopic flare patients. Stage 4 atopic dermatitis, extensive exfoliative dermatitis, and ongoing immunosuppressant therapy warrant dermatology consultation first.