Photosensitive patients are at high risk of year-round low Vitamin D status, finds UK study 

A study part-funded by the British Skin Foundation has found that photosensitive patients are at a high risk of year-round low vitamin D status, rather than just in the winter months. Photosensitivity disorders are characterised by abnormal skin reactions to UV which include the following; polymorphic light eruption; chronic actinic dermatitis; solar urticaria; and forms of lupus erythematosus – in addition to sensitivity caused by certain medications.

This study took place in Greater Manchester with patients from the Photobiology Unit, Dermatology Centre, Salford Royal NHS Foundation Trust. It focused on sunlight exposure, photoprotective-behaviour (sun protection from clothes and sunscreen), oral vitamin D intake (from both diet and supplements) and vitamin D levels in the blood (vitamin D ‘status’) in 53 patients with moderate to severe photosensitivity, in comparison with healthy adults.

Ultraviolet light from the sun helps the body to produce vitamin D, which is essential for bone health. During the winter in places at northerly latitudes, many people become low in vitamin D. Photosensitive patients are asked to minimise their sun exposure, but the impact of this advice on people’s risk of having low vitamin D is unknown.

The study found that the behaviour of photosensitive patients is the main cause for year-round low vitamin D status, rather than just the winter months. Insufficient (defined as <20ng/ml; 59nmol/l) and even deficient (<10ng/ml; 25nmol/l) levels occurred at the peak of summer in 47 per cent and 9 per cent of patients respectively, rising to 73 per cent and 32 per cent mid-winter. In patients, mean vitamin D levels were 18 per cent lower in summer and 25 per cent lower in winter than in healthy adults.

Patients received lower doses of UVB at the weekends (i.e. leisure time), exposed less skin to the sun and used sunscreen more than healthy adults, while average oral vitamin D intake was low in both groups. The researches claim that targeted guidance on oral supplements is needed for photosensitive patients and their physicians.

Matthew Patey, Chief Executive of the British Skin Foundation says: “Whilst the outcome of this research shows the need for guidance in regards to vitamin D intake, it is important to remember that protecting the skin from sunburn is still key and that patients can obtain vitamin D from dietary sources and supplements.”

Professor Lesley Rhodes explains, “Photosensitive patients are disadvantaged in many ways, through their need to avoid sun exposure. This study is the first to examine vitamin D levels in photosensitive and healthy people side by side throughout the year. A key finding is their high risk of year-round low vitamin D levels, contrasting with seasonal lows in healthy people, with potentially greater negative impact on health. National guidance on vitamin D supplements should specifically mention this at-risk group, in order to alert these patients and their doctors.”

Image: British Skin Foundation

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