The researchers, led by Dr Zulf Mughal, recruited 51 teenage girls with an average age of 15.3 years. Fourteen girls were white, and the other 37 were non-white. Dietary intake of vitamin D and calcium were assessed using food frequency questionnaires, and skin exposure to sunlight was also calculated based on typical everyday clothing cover. The girls also had blood samples taken to measure levels of calcium and 25- hydroxyvitamin D (25(OH)D), the non-active ‘storage’ form of the vitamin.
The researches report that 73 per cent of the girls (37 girls) were vitamin D deficient, with levels of 25(OH)D below 30 nanomoles per litre of serum.
Worryingly, nine girls (17 per cent) had levels below 12.5 nanomoles per litre. These low levels are typically associated with rickets and osteomalacia.
“Avoidance of exposure to sunshine for religious and cultural beliefs that encourage wearing of concealing clothing and restriction of outdoor activities has previously been reported as a risk factor for vitamin D deficiency in Saudi Arabian adolescents.
“Increased skin pigmentation is a further factor that might explain the difference in vitamin D status of white and non-white girls in our study,” wrote the researchers.
UK researchers recently proposed 10 to 15 minutes of unprotected exposure to the midday sun as a good source of the vitamin. In the US, where over 1.5 million people are diagnosed with skin cancer every year, experts are pushing supplements, claiming recommendations for sun exposure are “highly irresponsible”.
By this thinking, the best source could be from fortified foods and supplements.
Steve - UK researchers are right on with the 10 to 15 minutes of unprotected sun exposure. Although, for much of the year, that is not possible in Northern climates, so supplementation from sources such as cod Liver Oil is warranted.
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