Epidemiology and Prevention of Vitamin A Deficiency Disorders

A century of cascading vitamin discovery, public health assessment and deficiency prevention began with vitamin A (VA). Largely brought under control in high-income countries in the past century, VA deficiency continues to affect infants, preschool age children and women of reproductive age in impoverished and undernourished populations. Many stresses contribute to VA deficiency. The extent of VA deficiency has been globally understood, generally, through two indicators: population distributions of serum (or plasma) retinol concentration, interpreted to reflect deficiency when <0.70 μmol/l (20 μg/dl), and the prevalence of xerophthalmia, classified by stages of night blindness. VA deficiency can be effectively prevented in a complementary manner through approaches that include supplementation, fortification, biofortification and improving dietary diversity, with the choice of approaches guided by urgency, epidemiological patterns and local resources. VA supplementation is an effective strategy for preventing VA deficiency disorders (VADD).