Psoriasis is a skin condition characterised by raised, red, often-inflamed patches of skin. Typical sites include the front of the knees, the back of the elbows and the scalp. The condition tends to be chronic – in other words it tends to be a long-term problem, with improvements and exacerbations in time.
One thing that many psoriasis sufferers bear testament to is the fact that the condition improves when on holiday. Specifically, when on holiday in the sun. And the evidence for the improvement that psoriasis sufferers see in the sun is not just anecdotal: last year I reported on a study where this concept was actually put to the test (with impressive results). See here for more about this.
Some people have theorised that the benefits of sunlight for psoriasis sufferers is mediated through the production of vitamin D. In the study linked to above, sunlight therapy almost doubled vitamin D levels, and vitamin D is believed to have ‘anti-proliferative’ function in the body. This may be relevant as psoriasis is essentially a condition of excessive proliferation of skin cells.
Now, while sunlight may be an effective treatment for psoriasis, not everyone has as much access to sunlight as they would wish. It’s the rare bird who can travel to warmer, sunnier climes as often as they would like, and some people are at an inherent disadvantage should they live in a country that does not get much in the way of natural sunlight. Like, say, the Irish.
I was interested today to read about a study of Irish psoriasis sufferers [1]. In this study, individuals had their vitamin D levels checked and then half the group were subjected to ultraviolet B (UVB) therapy three times a week, while the other half were not. The study took place over a four-month period spanning the winter (this may be relevant as vitamin D levels and sunlight exposure tend to bottom out at this time).
In those who received the UVB treatment, psoriasis was significantly helped. Median psoriasis scores dropped from 7.1 to 0.5. Basically, the psoriasis in those treated with UVB cleared. Psoriasis severity did not improve in those not receiving treatment.
UVB treatment also led to an improvement in vitamin D levels from a median of 23 ng/ml (57.5 nmol/l) to 59 ng/ml (147.5 nmol/l). No significant increase was seen in those not receiving UVB therapy. In fact, in this group, 75 per cent were deemed to be vitamin D ‘insufficient’ (< 20 ng/ml).
This study adds to the evidence linking light exposure with improvements in psoriasis. It also supports the idea that UVB therapy is a valid alternative to actual sunlight for helping psoriasis symptoms and boosting vitamin D levels.
References:
1. Ryan C, et al. The Effect of Narrowband UV-B Treatment for Psoriasis on Vitamin D Status During Wintertime in Ireland. Arch Dermatol. 2010;146(8):836-842
