Can you still be Vitamin D deficient despite living in a place with plenty of sun all year?

10 June 2021

Research over the past 2 decades have shown that Vitamin D deficiency is pandemic [1–3]. Nearly every country in the world has a large majority of their population with a low Vitamin D status, and which is moreover often times deficient. Deficiency means that the circulating 25(OH)D blood level is below 20 ng/mL (or 50 nmol/L).

Moreover, this Vitamin D deficiency pandemic concerns every age group from infants to the elderly, every race and gender, and more surprisingly it is as widespread in countries with plenty of sun all year long as in North America and Europe. For example, severe Vitamin D deficiency and insufficiency have been recorded in countries like India, Brazil and Iran, but also in the south of the USA in states which have a lot of sun all year such as Arizona and Florida.

A large national survey, spanning one decade (2001-2010) in the USA and with nearly 26,000  participants, showed that between 70 and 75% of adults (over 18 y.o.) were either deficient or had an insufficient amount of Vitamin D in their blood [4]. In India these numbers were even higher, with over 80% of adults and 90% of infants who had either deficiency or insufficiency! The graph below illustrates this data. Please note that insufficiency is defined as a circulating 25(OH)D blood level below 30 ng/mL (or 75 nmol/L).

Figure 1: Vitamin D deficiency or insufficiency in the USA and in India for different age groups.

This data clearly shows that sun exposure alone is not enough to prevent vitamin D deficiency. Moreover, few people really know how Vitamin D is produced in the skin, when they should expose their skin to the sun, for how long, and how often, in order to synthesize enough Vitamin D. We’ll talk about some of these important questions in the next post, so stay tuned for more!

References:

  1. Van Schoor, N.M.; Lips, P. Worldwide Vitamin D Status. Best Pract. Res. Clin. Endocrinol. Metab. 2011, 25, 671–680.
  2. Mithal, A.; Wahl, D.A.; Bonjour, J.P.; Burckhardt, P.; Dawson-Hughes, B.; Eisman, J.A.; El-Hajj Fuleihan, G.; Josse, R.G.; Lips, P.; Morales-Torres, J.; et al. Global vitamin D status and determinants of hypovitaminosis D. Osteoporos Int. 2009, 20, 1807–1820.
  3. Van der Meer, I.M.; Middelkoop, B.J.; Boeke, A.J.; Lips, P. Prevalence of vitamin D deficiency among Turkish, Moroccan, Indian and sub-Sahara African populations in Europe and their countries of origin: An overview. Osteoporos. Int. 2011, 22, 1009–1021.
  4. Liu, X., Baylin, A., & Levy, P. (2018). Vitamin D deficiency and insufficiency among US adults: Prevalence, predictors and clinical implications. British Journal of Nutrition, 119(8), 928-936.

Leave a Comment

Your email address will not be published. Required fields are marked *