Fair-skinned people may need more dietary vitamin D intake

Sun-sensitive people tend to be deficient in vitamin D and may need dietary supplements to get adequate blood levels, says a new UK study.

In the study, vitamin D blood concentrations were measured in 1,200 people, some with skin cancer (melanoma) and some without (1). The study results showed that 730 of the participants had below normal vitamin D levels, defined as less than 60nmol/L in the trial, a level which research suggests can be associated with healthy benefits. Pale-skinned people and melanoma patients in particular were among the participants most likely to show low vitamin D levels. They did not achieve optimal vitamin D levels without supplementation.

The researchers commented that people with pale skin tend to be more prone to sunburns and skin cancer. So, they often take steps to avoid the sun and slather on sunscreen when they are exposed to the sunlight. As a result, they may produce less vitamin D, increasing their risk for bone loss, heart disease and cancer. Thus, they would benefit from vitamin D supplements. In addition, people with melanoma may have low levels of vitamin D and need supplements, suggested the scientists. Other research has shown that more than three-quarters of cancer patients have insufficient levels of vitamin D (25-hydroxy-vitamin D) and the lowest levels are associated with more advanced cancer.

Vitamin D blood levels are determined in part by sun exposure and pigmentation, so that darker-skinned people tend to have lower levels compared with paler-skinned people living at the same latitude (2). Recent evidence suggested, however, that within white-skinned populations, the very fair surprisingly have lower vitamin D levels, which may result from different behaviors in the sun (3). Latest studies reported that a variation in the gene coding for the vitamin D-binding protein is associated with low serum levels (4). Carriers of such polymorphisms may therefore require higher levels of supplementation. The US Institute of Medicine (IOM) recently raised the recommended daily intake to 600 international units ( IU) for everyone aged 1–70 and to 800 IU for adults older than 70.

1. Davies J. R. et al. The determinants of serum vitamin D levels in participants in a melanoma case–control study living in a temperate climate. Cancer Causes Control. 2011; 22:1471–1482.
2. Dawson-Hughes B. Racial/ethnic considerations in making recommendations for vitamin D for adult and elderly men and women. Am J Clin Nutr. 2004; 80:1763–1766.
3. Glass D. et al. Pigmentation and vitamin D metabolism in Caucasians: low vitamin D serum levels in fair skin types in the UK. PLoS One. 2009; 4:e6477.
4. Wang T. J. et al. Common genetic determinants of vitamin D insufficiency: a genome-wide association study. Lancet. 2010; 376:180–188.