Vitamin D status: sunshine is nice but other factors prevail

Excerpt

We welcome the letter by Ameri et al. which offers us an opportunity to emphasise the role of factors important for vitamin D status. Ameri et al. [1] point out that our paper “Is a daily supplementation with 40 microgram vitamin D₃ sufficient? A randomized controlled trial” is lacking a discussion on the role of location and latitude in vitamin D status. The amount of solar UV-B radiation is definitely of importance for the endogenous vitamin D synthesis; however, the issue about vitamin D status is far more complex than latitude and sunshine hours. Surprisingly, there seem to be a North–South gradient with significantly higher 25-hydroxyvitamin D (25(OH)D) values in the Northern parts of Europe (Fig. 1) and North America in comparison with the more Southern parts of the continents, recently reviewed by van Schoor and Lips [2]. In Europe, low 25(OH)D values are found in Greece, Italy and Spain, while Norway and Sweden have higher average values [2‐4]. High levels in Scandinavia may in part be due to a high intake of fatty fish, while the lower levels in Mediterranean countries may be due to sunshine avoiding behavior including covering clothes and staying indoors when the sun is high. Furthermore, the vitamin D status at one defined location may differ significantly between people of different ethic origin [5].

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