ESPE Yearbook of Paediatric Endocrinology

To read the full abstract: Lancet Glob Health 2020;8: e134–42. doi: 10.1016/S2214-109X(19)30457-7

• The results of 25OH Vit D determination from 129 studies including 21 474 participants in 23 African countries were analyzed.• Overall, a serum 25(OH)D concentration less than 30 nmol/L was found in 18.5% of the population and less than 75 nmol/l in 59.5% of the population.• Newborn babies, women and those living in urban areas were found to be at higher risk for low 25OH Vit D.

The article describes the magnitude of 25(OH)vitamin D (25(OH)D) deficiency in many African countries and highlights its role in the high prevalence of rickets reported in Africa. The authors do not comment on the potential reasons for the marked disparities in vitamin D deficiency between countries. For instance, the difference in mean 25(OH)D concentration in Ethiopia (46.5 nmol/l) compared to neighbouring Uganda (82.5 nmol/l) is striking. Is it due to different cultures/lifestyles (the Muslim population represents 12% in Uganda and 34% in Ethiopia), study bias (most of the studies are regional), government policies promoting administration of vitamin D, or to other factors? Many of the risk factors are difficult to modify, i.e. urban living (an increasing proportion of the population lives in cities), female sex (women tend to stay home more than men and, when going out, are more covered than men); geographical location away from the equator (where the sun’s UVs are less effective in generating vitamin D) and darker skin (which is less adapted to vitamin D synthesis). It is important to note that while the prevalence of rickets is generally high in Africa, 25(OH)D deficiency may not be the sole culprit. The consumption of milk (a major source of calcium) tends to be low in parts of Africa (for instance, 62 liters per capita per year in Uganda, which is similar to Europe and North America compared to 20 liters in Ethiopia). Overall, there seems to be enough data to support the development of government policies that promote vitamin D (and calcium) supplementation. The actual process for supplementation needs to be carefully considered: general supplementation vs focus on at-risk population (pregnant mothers and young children), oral vs parenteral administration of vitamin D (the presence of malabsorption may prevent absorption of oral vitamin D), over the counter vitamin supplements vs. food fortification (such as milk).