News about Light Therapy & Vitamin D Levels

UVB Light Therapy Increases Vitamin D Levels for Psoriasis Patients

November 2, 2010

Vitamin D is essential for many bodily processes, and some experts believe that abnormalities of vitamin D metabolism may be partly responsible for the worsening of psoriasis. Treating psoriasis with narrowband ultraviolet light B (UVB) phototherapy is a widely accepted practice.

But what effect, if any, does UVB light therapy have on vitamin D levels? To find out, researchers in Dublin, Ireland, exposed 30 patients with plaque psoriasis to narrowband UVB phototherapy (311 to 313 nm) three times a week until their psoriasis cleared. A control group of 30 people with psoriasis were not treated with light therapy. The trial period occurred between late October 2008 and early February 2009, when production of vitamin D from sun exposure would be at a wintertime minimum.

In the group receiving phototherapy, blood levels of vitamin D increased significantly from a median of 23 ng/mL to 59 ng/mL after treatment; there was no change in the control group's levels of vitamin D. Similarly, the phototherapy group had sufficient levels of vitamin D at the study's end, while 75% of the control group was vitamin D-insufficient, with levels under 20 ng/mL.

The severity of psoriasis decreased in the phototherapy group and was unchanged in the control group. However, the people who required the most exposures to UVB before their skin cleared also had the highest levels of vitamin D, leading researchers to conclude that "the improvement in both vitamin D status and psoriasis are contemporaneous, but unrelated, consequences of narrowband UVB, or that there is another explanation for the causal relationship."

The results from this Dublin-area study are meaningful in other high-latitude regions, the authors believe, since people in many high-latitude areas of the world experience vitamin D deficiencies, especially during winter months. Nutritional supplements may be needed by those people to prevent the harmful effects of vitamin D deficiency.

Sources: Caitriona Ryan, et al. "The Effect of Narrowband UV-B Treatment for Psoriasis on Vitamin D Status During Wintertime in Ireland." Archives of Dermatology, 2010;146(8):836-842; and Pranita Vemulapalli, BS; Henry W. Lim, M.D. "Phototherapy and Vitamin D." Archives of Dermatology, August 2010. 2010;146(8):906-908. doi:10.1001/archdermatol.2010.193.

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