Solar ultraviolet radiation (UVR) is required for cutaneous vitamin D synthesis, and experimental studies have indicated the sun exposure levels required to avoid a vitamin D deficient status. A recent study, published in the journal International Journal of Environmental Research and Public Health, examined the sun exposure habits of different UK population and pointed that overall sun exposure across northern England, UK was low, particularly amongst South Asians.
Researchers used data from a series of studies involving 578 volunteers, which took place during 5-year period between 2007 and 2011 in Greater Manchester, UK. Study population involved healthy white Caucasian adolescents and working-age adults (skin type I–IV), healthy South Asian working-age adults (skin type V) and adults with photodermatoses. Polysulphone dosimeter badges assessed the sun exposure levels while daily dietary logs assessed intake of vitamin D-containing foods and supplements.
Sun exposure across different age groups and ethnicities in northern England, UK was low (<3% ambient UVR), but it was particularly low (~1%) amongst South Asians. This sun exposure was the major vitamin D source as dietary intake and supplement use was low, particularly in South Asians. Sun exposure levels prevented winter vitamin D deficiency in 95% of healthy white adults and 83% of adolescents, while 32% of the photodermatoses group and >90% of the healthy South Asians were deficient. Less sun exposure of the skin when outdoors, less oral vitamin D and melanisation adversely affected vitamin D status in South Asians.
Authors commented: “South Asians and those with photodermatoses, who have medical reasons to minimise sun exposure, require increased oral vitamin D, whilst the sun exposure they gain provides a tangible contribution.”