Global prevalence of vitamin A deficiency in population at risk: 1995-2005
Summary of the global prevalence of vitamin A deficiency in populations at risk
In 1987, WHO estimated that vitamin A deficiency was endemic in 39 countries based on the ocular manifestations of xerophthalmia or deficient serum (plasma) retinol concentrations (<0.35 µmol/l). In 1995, WHO updated these estimates and reported that vitamin A deficiency was of public health significance in 60 countries, and was likely to be a problem in an additional 13 countries. The current estimates reflect the time period between 1995 and 2005, and indicate that 45 and 122 countries have vitamin A deficiency of public health significance based on the prevalence of night blindness and biochemical vitamin A deficiency (serum retinol concentration <0.70 µmol/l), respectively, in preschool-age children.
In this present edition, estimates of vitamin A deficiency are provided for preschool-age children as in the previous edition, and also for pregnant women. They are based on an increasingly assessed history of night blindness and a now more widely adopted serum (plasma) retinol concentration, using a cut-off of <0.70 µmol/l (<20 µg/dl) to define deficiency.
Globally, night blindness is estimated to affect 5.2 million preschool-age children (95% CI: 2.0-8.4 million) and 9.8 million pregnant women (95% CI: 8.7-10.8 million), which corresponds to 0.9% and 7.8% of the population at risk of VAD, respectively. Low serum retinol concentration (<0.70 µmol/l) affects an estimated 190 million preschool-age children (95% CI: 178-202 million) and 19.1 million pregnant women (95% CI: 9.30-29.0 million) globally. This corresponds to 33.3% of the preschool-age population and 15.3% of pregnant women in populations at risk of VAD, globally. The WHO Regions of Africa and South-East Asia were found to be the most affected by vitamin A deficiency for both population groups.
Despite a marked increase in submitted data, there are still numerous countries lacking national prevalence data. There is a need to inform and motivate governments and agencies to collect, and report to WHO, national data on the prevalence of deficiency and, whenever possible, vitamin A programme coverage conditions prevailing at the time that population assessment data were collected.
We hope that readers will find this report useful and feel free to share any comments with us (firstname.lastname@example.org). We also hope that this information will contribute to our common goal to eliminate vitamin A deficiency as a public health problem.