Researchers in Egypt report a link between vitamin D deficiency and vitiligo, an autoimmune skin disease characterized by loss of pigmentation (brown color) from areas of the skin.
Vitiligo may appear at any age, affecting about 1 out of every 100 people in the United States. Vitiligo is often associated with existing autoimmune conditions including lupus, type 1 diabetes, hypo and hyperthyroidism, and rheumatoid arthritis.
Hanan M Saleh and colleagues at the Department of Dermatology and Venereology in Cairo set out to evaluate vitamin D status in vitiligo patients with and without systemic autoimmune diseases.
The researchers conducted a case-control study, randomly selecting 40 vitiligo patients; 20 with systemic autoimmune disease, 20 without autoimmune disease. The authors included 40 age, gender, and skin type matched control participants.
After assessment of 25(OH)D status, physical examination, and medical history, the authors found:
- No statistical difference between age, gender, skin type, or reported vitamin D intake.
- There was a highly statistical significance between occupations of the vitiligo vs control groups. Eighty-seven percent of control participants worked outdoors.
- There was a significant difference between both groups regarding duration of vitiligo (p=0.008). Participants with vitiligo, without autoimmune disease had the disease for an average of 5.5 years compared to 2 years for those with vitiligo and autoimmune disease.
- 97.5% of vitiligo participants were vitamin D deficient, while only 12.5% of controls were deficient (p=0.0001).
- There was no statistical difference between vitamin D status of patients with vitiligo and autoimmune diseases (group 1) and patients without autoimmune diseases (group 2), although slightly lower levels were found in group 1.
The authors conclude,
“The key question is whether low 25(OH)D levels in vitiligo patients confer greater risk of developing secondary autoimmunity or autoimmune inflammatory processes consumes excess vitamin D…Whether low 25(OH)D levels are the consequence or the cause of autoimmune disease, 25(OH)D screening may be a worthwhile screen for vitamin D deficiency and hence vitamin D supplementation to control autoimmunity. Given its relative safety in conjunction with its beneficial immunomodulatory effects, there is optimism that correcting vitamin D deficiency will lead to better outcomes for vitiligo patients.”
The authors recognize several limitations of the study, including the failure to match occupation of patients and controls, which could explain the significant difference between vitamin D blood levels between the two groups. The researchers call for future trials with larger sample size and matching patients and controls with similar sun exposure habits.
Saleh HMA, Abdel Fattah NSA, Hamza HMM. Evaluation of serum 25-hydroxyvitamin D levels in vitiligo patients with and without autoimmune diseases. Photodermatology, Photoimmunology & Photomedicine. Feb 2013.