Back نقص فيتامين أ Arabic Nedostatak vitamina A BS Carència de vitamina A Catalan Vitamin-A-Mangel German Deficiencia de vitamina A Spanish کمبود ویتامین آ Persian Carence en vitamine A French מחסור בוויטמין A HE Վիտամին A-ի անբավարարություն Armenian Kekurangan vitamin A ID

Vitamin A deficiency

Prevalence of vitamin A deficiency, 1995-2005

Vitamin A deficiency (VAD) or hypovitaminosis A is a lack of vitamin A in blood and tissues.[1] It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries.[1] Vitamin A plays a major role in phototransduction, so this deficiency impairs vision, often presenting with nyctalopia (night blindness).[1] In more severe VAD cases, it can progress to xerophthalmia, keratomalacia, and complete blindness.[1]

Vitamin A deficiency is the leading cause of preventable childhood blindness worldwide and is a major cause of childhood mortality.[1] Each year, approximately 250,000 to 500,000 malnourished children in the developing world go blind from a VAD, with about half of whom dying within a year of losing their sight.[2] Addressing VAD has been a critical focus of global health initiatives, including Sustainable Development Goal 2: to end hunger, achieve food security and improved nutrition and promote sustainable agriculture.[3]

In pregnant women, VAD is associated with a high prevalence of night blindness and poor maternal health outcomes including an increased risk of maternal mortality and complications during pregnancy and lactation.[4][5][6][7] VAD also affects the immune system and diminishes the body's ability to fight infections.[1] In countries where children are not immunized, VAD is linked to higher fatality rates from infectious diseases such as measles.[1] Even mild, subclinical deficiency can also be a problem, as it may increase children's risk of developing respiratory and diarrheal infections, decrease growth, impair bone development, and reduce their likelihood of surviving serious illnesses.[6]

Globally, VAD is estimated to affect about one-third of children under the age of five, causing an estimated 670,000 deaths in children under five annually.[8][9] It is most prevalent in sub-Saharan Africa (48 percent) and South Asia (44 percent).[8] Although VAD is well-managed in many high income nations, it remains a significant concern in resource-poor settings. Public health interventions, such as vitamin A supplementation, reached 59% of targeted children in 2022, highlighting the ongoing need for comprehensive efforts to combat VAD.[8]

  1. ^ a b c d e f g "Vitamin A". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis. January 2015. Archived from the original on 27 April 2021. Retrieved 1 November 2019.
  2. ^ Cite error: The named reference who98 was invoked but never defined (see the help page).
  3. ^ "Goal 2 | Department of Economic and Social Affairs". sdgs.un.org. Retrieved 17 December 2024.
  4. ^ "WHO Vitamin A deficiency | Micronutrient deficiencies". Archived from the original on 16 August 2019. Retrieved 3 March 2008.
  5. ^ Latham, Michael E. (1997). Human Nutrition in the Developing World (Fao Food and Nutrition Paper). Food & Agriculture Organization of the United. ISBN 92-5-103818-X.
  6. ^ a b Sommer, Alfred (1995). Vitamin a Deficiency and Its Consequences: A Field Guide to Detection and Control. Geneva: World Health Organization. ISBN 92-4-154478-3.
  7. ^ "A world fit for children" (PDF). Archived (PDF) from the original on 12 October 2017. Retrieved 3 March 2008.
  8. ^ a b c "Vitamin A Deficiency in Children". UNICEF DATA. Retrieved 17 December 2024.
  9. ^ Black RE et al., Maternal and child undernutrition: global and regional exposures and health consequences, The Lancet, 2008, 371(9608), p. 253.
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