Psoriasis patients often lack vitamin D
MedWire News: People with psoriasis are often lacking in vitamin D and may need to take supplements, particularly in the winter, Italian experts believe.
They suggest that people with the skin condition may benefit from being screened for vitamin D insufficiency "for a more comprehensive management" of their disease.
Psoriasis is a disease of the body's immune system that causes symptoms such as itching, flaking, and scaling of the skin. It can also cause problems with the joints, a form of the condition known as psoriatic arthritis.
Vitamin D deficiency is currently a "hot topic" in medicine because of its associations with a range of diseases including osteoporosis, heart disease, certain cancers, and some autoimmune diseases.
Vitamin D is made in the body, upon exposure to sunlight, and can also be found in foods such as fortified milk, butter, eggs, and fatty fish.
"Vitamin D insufficiency is extremely common in USA and Europe where its prevalence is estimated to be as high as 50 to 80% in the general population," explain Dr Paolo Gisondi (University of Verona) and colleagues.
In this study, Dr Gisondi's team measured vitamin D levels in 145 patients with psoriasis, 112 patients with rheumatoid arthritis (also an autoimmune disease), and 141 healthy volunteers.
They found that vitamin D levels were lower, on average, in the patients with psoriasis and in those with rheumatoid arthritis compared with healthy volunteers.
Furthermore, patients with psoriasis or rheumatoid arthritis were much more likely to be considered "vitamin D deficient" than healthy individuals.
Vitamin D deficiency varied according to the time of year, in line with the amount of sunshine, say the researchers. During the summertime around half of patients were lacking in vitamin D whereas in wintertime as many as four out of five patients were deficient.
The researchers used statistical techniques to show that the association between psoriasis and vitamin D deficiency was unlikely to be explained by other potentially "confounding" factors such as age, gender, or body weight - which are also known to influence vitamin D levels.
Writing in the British Journal of Dermatology, Dr Gisondi and colleagues say their findings are relevant because vitamin D is known to have effects in the body that could be associated with the development of psoriasis.
Vitamin D is also known to be involved in the response to certain treatments for psoriasis, such as "sunlight" therapy, and it has been proposed that vitamin D could be an effective treatment for the condition.
"In conclusion, vitamin D deficiency may be common in patients with psoriasis, especially in winter time," the researchers write. "Therefore, patients could be routinely screened for vitamin D insufficiency for a more comprehensive management."
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By Joanna Lyford