Comment on Wahl et al.: A global representation of vitamin D status in healthy populations

Abstract

Dear Editor, With great interest, I read the paper by Wahl et al. [1]. I was surprised, however, that the color code in the map on vitamin D status in adults is yellow (25OHD 50–74 nmol/L) for Saudi Arabia. We [2] and others [3, 4] have shown that moderately severe vitamin D deficiency is highly prevalent in many countries of the Arabian Peninsula, including Saudi Arabia. It is important to highlight that the reference quoted for Saudi Arabia [5] refers to a study on reference intervals of biochemical bone turnover markers. In that study, the authors excluded women whose serum 25OHD levels were <50 nmol/L. Please refer to page 805 of that publication, where under study design the authors wrote “Women who are... vitamin D-deficient with serum 25-hydroxy-vitamin D (25(OH)D) levels being <50 nmol/L were also excluded.” In fact, in another publication by the same group [6], mean (SD) 25OHD level in 1,172 Saudi Arabian women (age 50.9± 12.6 years; range 20–79 years) was 35.8±26.9 nmol/L. In the 501 premenopausal women (age 39.7±7.8 years), 25OHD was 43.0±30.5 nmol/L, and in the 671 postmenopausal women (age 58.7±7.5 years), 25OHDwas 33.3±24.9 nmol/L. The same group has also published their data on Saudi Arabian men [7], where 25OHD level in 834 men (age 42.1±13.9 years; range 20–74 years) was 29.0±16.1 nmol/L. I propose that the levels published in the latter two papers be used for Saudi Arabia in the revised version of the map, thus changing the color code from yellow to orange (25OHD 25–49 nmol/L)!