View source for Medicine:Vitamin A deficiency

{{Short description|Disease resulting from low Vitamin A concentrations in the body}}
[[File:Vitamin A deficiency.PNG|thumb|upright=1.6|Prevalence of vitamin A deficiency, 1995<br />{{col begin}}
{{col-2}}{{legend|#F30B18|Clinical}} {{legend|#FE841D|Severe subclinical}}{{legend|#F4B849|Moderate subclinical}}{{col-2}}{{legend|#817C1C|Mild subclinical}} {{legend|#127E10|VAD under control}}{{legend|#7DCBF2|No data available}}{{col end}}]]

'''Vitamin A deficiency''' ('''VAD''') or '''hypovitaminosis A''' is a lack of [[Chemistry:Vitamin A|vitamin A]] in [[Biology:Blood|blood]] and [[Biology:Tissue|tissues]].<ref name="lpi">{{cite web |url=http://lpi.oregonstate.edu/mic/vitamins/vitamin-A |title=Vitamin A |publisher=Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis |date=January 2015 |access-date=1 November 2019 |archive-date=27 April 2021 |archive-url=https://web.archive.org/web/20210427223156/https://lpi.oregonstate.edu/mic/vitamins/vitamin-A |url-status=live }}</ref> It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries.<ref name=lpi/> [[Medicine:Nyctalopia|Nyctalopia]] (night blindness) is one of the first signs of VAD, as the vitamin has a major role in [[Biology:Visual phototransduction|phototransduction]];<ref name=lpi/> but it is also the first symptom that is reversed when vitamin A is consumed again. [[Medicine:Xerophthalmia|Xerophthalmia]], [[Medicine:Keratomalacia|keratomalacia]], and complete blindness can follow if the deficiency is more severe.<ref name=lpi/>

Vitamin A deficiency is the world's leading cause of preventable [[Medicine:Childhood blindness|childhood blindness]],<ref name=lpi/> and is critical to achieving Millennium Development Goal 4 to reduce child mortality. About 250,000 to 500,000 malnourished children in the developing world go blind each year from a deficiency of vitamin A, around half of whom die within a year of becoming blind.<ref name="who98" /> The {{wipe|United Nations}} Special Session on Children in 2002 set a goal of the elimination of VAD by 2010.<ref>{{Cite web|url=https://news.rutgers.edu/research-news/preventing-vitamin-deficiency-little-friendly-bacteria-might-go-long-way/20111219|title=In Preventing Vitamin A Deficiency, a Little Friendly Bacteria Might Go a Long Way|date=19 December 2011|website=Rutgers Today|language=en|access-date=27 October 2019}}</ref>

The prevalence of night blindness due to VAD is also high among pregnant women in many developing countries. VAD also contributes to maternal mortality and other poor outcomes in [[Medicine:Pregnancy|pregnancy]] and [[Biology:Lactation|lactation]].<ref name="WHO Vitamin A deficiency | Micronutrient deficiencies">{{cite web |url=https://www.who.int/nutrition/topics/vad/en/ |title=WHO Vitamin A deficiency &#124; Micronutrient deficiencies |access-date=3 March 2008 |archive-date=16 August 2019 |archive-url=https://web.archive.org/web/20190816130048/https://www.who.int/nutrition/topics/vad/en/ |url-status=live }}</ref><ref name="isbn92-5-103818-X">{{cite book |author=Latham, Michael E. |title=Human Nutrition in the Developing World (Fao Food and Nutrition Paper) |publisher=Food & Agriculture Organization of the United|year= 1997|isbn=92-5-103818-X}}</ref><ref name="isbn92-4-154478-3">{{cite book |author=Sommer, Alfred |title=Vitamin a Deficiency and Its Consequences: A Field Guide to Detection and Control |publisher=World Health Organization |location=Geneva |year= 1995|isbn=92-4-154478-3}}</ref><ref name="A world fit for children">{{cite web |url=http://www.unicef.org/worldfitforchildren/files/A-RES-S27-2E.pdf |title=A world fit for children |access-date=3 March 2008 |archive-date=12 October 2017 |archive-url=https://web.archive.org/web/20171012150607/https://www.unicef.org/worldfitforchildren/files/A-RES-S27-2E.pdf |url-status=live }}</ref>

VAD also diminishes the ability to fight infections.<ref name=lpi/> In countries where children are not immunized, infectious diseases such as [[Medicine:Measles|measles]] have higher fatality rates.<ref name=lpi/> As elucidated by Alfred Sommer, even mild, subclinical deficiency can also be a problem, as it may increase children's risk of developing respiratory and diarrheal infections, decrease growth rate, slow bone development, and decrease likelihood of survival from serious illness.<ref name="isbn92-4-154478-3"/>

VAD is estimated to affect about one-third of children under the age of five around the world.<ref>World Health Organization, Global prevalence of vitamin A deficiency in populations at risk 1995–2005, WHO global database on vitamin A deficiency.</ref> It is estimated to claim the lives of 670,000 children under five annually.<ref>Black RE et al., Maternal and child undernutrition: global and regional exposures and health consequences, The Lancet, 2008, 371(9608), p. 253.</ref> Around 250,000–500,000 children in developing countries become blind each year owing to VAD, with the highest prevalence in Southeast Asia and Africa. According to the World Health Organization (WHO), VAD is under control in the United States, but in developing countries, VAD is a significant concern. Globally, 65% of all children aged 6 to 59 months received two doses of vitamin A in 2013, fully protecting them against VAD (80% in the [[Finance:Least developed countries|least developed countries]]).<ref name="UNICEF Data Vitamin A Deficiency">{{cite web |url=http://data.unicef.org/nutrition/vitamin-a.html |title=Vitamin A Deficiency and Supplementation UNICEF Data |access-date=7 April 2015 |archive-date=11 September 2016 |archive-url=https://web.archive.org/web/20160911232937/http://www.data.unicef.org/nutrition/vitamin-a.html |url-status=live }}</ref>

==Signs and symptoms==
Vitamin A deficiency is the most common cause of blindness in developing countries. The WHO estimated in 1995 that 13.8 million children had some degree of visual loss related to VAD.<ref>{{cite journal |vauthors = Rahi JS, Sripathi S, Gilbert CE, Foster A | year = 1995 | title = Childhood blindness due to VAD in India: regional variations | journal = Archives of Disease in Childhood | volume = 72 | issue = 4| pages = 330–33 | doi=10.1136/adc.72.4.330| pmid = 7763066 | pmc = 1511233 }}</ref> Night blindness and its worsened condition, [[Medicine:Xerophthalmia|xerophthalmia]], are markers of Vitamin A deficiency; collections of [[Biology:Keratin|keratin]] in the [[Medicine:Conjunctiva|conjunctiva]], known as [[Medicine:Bitot's spots|Bitot's spots]], and ulceration and necrosis of cornea [[Medicine:Keratomalacia|keratomalacia]] can be seen. Conjunctival epithelial defects occur around lateral aspect of the [[Medicine:Corneal limbus|limbus]] in the subclinical stage of VAD. These conjunctival epithelial defects are not visible on a biomicroscope, but they take up black stain and become readily visible after instillation of kajal (surma); this is called "Imtiaz's sign".<ref>{{Cite web |url=http://www.paramountbooks.com.pk/LoginIndex.asp?title=Concise-Ophthalmology-(pb)-2014&Isbn=9789696370017&opt=3&sUBcAT=06 |title=Untitled Document |access-date=15 August 2014 |archive-date=30 July 2014 |archive-url=https://web.archive.org/web/20140730052246/http://www.paramountbooks.com.pk/LoginIndex.asp?title=Concise-Ophthalmology-(pb)-2014&Isbn=9789696370017&opt=3&sUBcAT=06 |url-status=dead }}</ref>

===Night blindness===
{{Main|Nyctalopia}}A process called [[Biology:Adaptation (eye)|dark adaptation]] typically causes an increase in photopigment amounts in response to low levels of illumination. This occurs to an enormous magnitude, increasing light sensitivity by up to 100,000 times its sensitivity in normal daylight conditions. VAD affects vision by inhibiting the production of [[Biology:Rhodopsin|rhodopsin]], the photopigment responsible for sensing low-light situations. Rhodopsin is found in the [[Biology:Retina|retina]] and is composed of [[Chemistry:Retinal|retinal]] (an active form of vitamin A) and [[Biology:Opsin|opsin]] (a protein).

Night blindness caused by VAD has been associated with the loss of [[Biology:Goblet cell|goblet cell]]s in the conjunctiva, a membrane covering the outer surface of the eye. Goblet cells are responsible for secretion of [[Biology:Mucus|mucus]], and their absence results in xerophthalmia, a condition where the eyes fail to produce tears. Dead epithelial and microbial cells accumulate on the conjunctiva and form debris that can lead to infection and possibly blindness.<ref>Underwood, Barbara A. Vitamin A Deficiency Disorders: International Efforts to Control A Preventable "Pox." J. Nutr. 134: 231S–236S, 2004.</ref>

Decreasing night blindness requires the improvement of vitamin A status in at-risk populations. Supplements and fortification of food have been shown to be effective interventions. Supplement treatment for night blindness includes massive doses of vitamin A (200,000 IU) in the form of retinyl palmitate to be taken by mouth, which is administered two to four times a year.<ref>{{cite journal | vauthors = Sommer A, Muhilal, Tarwotjo I, Djunaedi E, Glover J | s2cid = 35416519 | year = 1980b | title = Oral versus intramuscular vitamin A in the treatment of xerophthalmia| journal = Lancet | volume = 1 | issue = 8168 Pt 1| pages = 557–559 | doi = 10.1016/S0140-6736(80)91053-3 | pmid = 6102284 }}</ref> Intramuscular injections are poorly absorbed and are ineffective in delivering sufficient bioavailable vitamin A. Fortification of food with vitamin A is costly, but can be done in wheat, sugar, and milk.<ref>{{cite journal | vauthors = Arroyave G, Mejia LA, Aguilar JR | year = 1981 | title = The effect of vitamin A fortification of sugar on the serum vitamin A levels of preschool Guatemalan children: a longitudinal evaluation| journal = J. Nutr. | volume = 34 | issue = 1| pages = 41–49 | doi=10.1093/ajcn/34.1.41| pmid = 7446457 | doi-access = free }}</ref> Households may circumvent expensive fortified food by altering dietary habits. Consumption of yellow-orange fruits and vegetables rich in carotenoids, specifically beta-carotene, provides provitamin A precursors that can prevent VAD-related night blindness. However, the conversion of carotene to retinol varies from person to person and bioavailability of carotene in food varies.<ref>{{cite journal |vauthors=Borel P, Drai J, Faure H, Fayol V, Galabert C, Laromiguière M, Le Moël G | title = Recent knowledge about intestinal absorption and cleavage of carotenoids | language = fr | journal = Annales de Biologie Clinique | volume = 63 | issue = 2 | pages = 165–177 | year = 2005 | pmid = 15771974 }}</ref><ref>{{cite journal |vauthors=Tang G, Qin J, Dolnikowski GG, Russell RM, Grusak MA | title = Spinach or carrots can supply significant amounts of vitamin A as assessed by feeding with intrinsically deuterated vegetables | journal = The American Journal of Clinical Nutrition | volume = 82 | issue = 4 | pages = 821–828 | year = 2005 | pmid = 16210712 | doi=10.1093/ajcn/82.4.821| doi-access = free }}</ref>

===Infection===
Along with poor diet, infection and disease are common in many developing communities.<ref name=lpi/> Infection depletes vitamin A reserves which in turn make the affected individual more susceptible to further infection.<ref name=lpi/> Increased incidence of [[Medicine:Xerophthalmia|xerophthalmia]] has been observed after an outbreak of measles, with mortality correlated with severity of eye disease.<ref name=lpi/> In longitudinal studies of preschool children, susceptibility to disease increased substantially when severe VAD was present.<ref name=lpi/>

The reason for the increased infection rate in vitamin A deficient individuals is that killer T-cells require the retinol metabolite [[Chemistry:Retinoic acid|retinoic acid]] to proliferate correctly.<ref name=lpi/> Retinoic acid is a ligand for nuclear retinoic acid receptors that bind the promoter regions of specific genes,<ref name="Cunningham and Duester">{{cite journal|last1=Cunningham|first1=T.J.|last2=Duester|first2=G.|date=2015|title=Mechanisms of retinoic acid signalling and its roles in organ and limb development|journal=Nat. Rev. Mol. Cell Biol.|volume=16|issue=2|pages=110–123|doi=10.1038/nrm3932|pmc=4636111|pmid=25560970}}</ref> thus activating [[Biology:Transcription|transcription]] and stimulating T cell replication.<ref name=lpi/> Vitamin A deficiency will often entail deficient retinol intake, resulting in a reduced number of T-cells and [[Biology:Lymphocyte|lymphocyte]]s, leading to an inadequate immune response and consequently a greater susceptibility to infections.<ref name=lpi/> In the presence of dietary deficiency of vitamin A, VAD and infections reciprocally aggravate each other.<ref name=lpi/>

==Causes==
In addition to dietary problems, other causes of VAD are known. [[Medicine:Iron deficiency|Iron deficiency]] can affect vitamin A uptake; other causes include [[Medicine:Fibrosis|fibrosis]], pancreatic insufficiency, [[Medicine:Inflammatory bowel disease|inflammatory bowel disease]], and small-bowel bypass surgery.<ref>{{cite web|url=http://emedicine.medscape.com/article/126004-clinical#b5|title=Vitamin A Deficiency Clinical Presentation: History, Physical, Causes|website=emedicine.medscape.com|access-date=21 September 2017|archive-date=21 September 2017|archive-url=https://web.archive.org/web/20170921145216/http://emedicine.medscape.com/article/126004-clinical#b5|url-status=live}}</ref> Protein energy malnutrition is often seen in VAD; suppressed synthesis of retinol binding protein (RBP) due to protein deficiency leads to reduced retinol uptake.<ref>(Combs, 1991).</ref> Excess alcohol consumption can deplete vitamin A, and a stressed liver may be more susceptible to vitamin A toxicity. People who consume large amounts of alcohol should seek medical advice before taking vitamin A supplements. In general, people should also seek medical advice before taking vitamin A supplements if they have any condition associated with fat malabsorption such as [[Medicine:Pancreatitis|pancreatitis]], [[Medicine:Cystic fibrosis|cystic fibrosis]], tropical sprue, and biliary obstruction. Other causes of vitamin A deficiency are inadequate intake, fat malabsorption, or liver disorders. Deficiency impairs immunity and hematopoiesis and causes rashes and typical ocular effects (e.g., xerophthalmia, night blindness).<ref>{{cite web|url=http://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/vitamin-a|title=Vitamin A – Nutritional Disorders|author=Merck Manuals Professional Edition|website=merckmanuals.com|access-date=17 March 2017|archive-date=18 March 2017|archive-url=https://web.archive.org/web/20170318001216/http://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/vitamin-a|url-status=live}}</ref>

==Diagnosis==
Initial assessment may be made based on clinical signs of VAD.<ref name=":0">{{Cite journal|last=Bates|first=C J|date=1 January 1999|title=Diagnosis and detection of vitamin deficiencies|journal=British Medical Bulletin|language=en|volume=55|issue=3|pages=643–657|doi=10.1258/0007142991902529|pmid=10746353|issn=0007-1420|doi-access=free}}</ref> Conjunctival impression cytology can be used to assess the presence of [[Medicine:Xerophthalmia|xerophthalmia]] which is strongly correlated with VAD status (and can be used to monitor recovery progress).<ref name=":0" /><ref name=":1">{{Cite web|url=https://www.medscape.org/viewarticle/724972_4|title=Diagnosis and Treatment of Vitamin A Deficiency: Workup|access-date=1 November 2019|archive-date=6 July 2017|archive-url=https://web.archive.org/web/20170706124116/http://www.medscape.org/viewarticle/724972_4|url-status=live}}</ref> Several methods of assessing bodily vitamin A levels are available, with HPLC the most reliable.<ref name=":1" /> Measurement of plasma retinol levels is a common laboratory assay used to diagnose VAD. Other biochemical assessments include measuring plasma retinyl ester levels, plasma and urinary retonioic acid levels, and vitamin A in breast milk.<ref name=":0" />

== Vitamin A sources ==
{{Excerpt|Vitamin A|Sources}}

==Prevention and treatment==
Treatment of VAD can be undertaken with both oral vitamin A and [[Medicine:Injection|injectable]] forms, generally as vitamin A palmitate.
* As an oral form, the supplementation of vitamin A is effective for lowering the risk of morbidity, especially from severe [[Medicine:Diarrhea|diarrhea]], and reducing [[Mortality rate|mortality]] from [[Medicine:Measles|measles]] and all-cause mortality. Vitamin A supplementation of children under five who are at risk of VAD can reduce all‐cause mortality by 23%.<ref>Beaton GH et al. Effectiveness of vitamin A supplementation in the control of young child morbidity and mortality in developing countries. United Nations Administrative Committee on Coordination, Sub-committee on Nutrition State-of-the-Art Series: Nutrition Policy Discussion Paper No. 13. Geneva, 1993.</ref> Some countries where VAD is a public-health problem address its elimination by including vitamin A supplements available in capsule form with national immunization days (NIDs) for [[Medicine:Polio|polio]] eradication or measles. Additionally, the delivery of vitamin A supplements, during integrated child health events such as child health days, has helped ensure high coverage of vitamin A supplementation in a large number of least developed countries. Child health events enable many countries in West and Central Africa to achieve over 80% coverage of vitamin A supplementation.<ref name="UNICEF Data Vitamin A Deficiency" /> According to UNICEF data, in 2013 worldwide, 65% of children between the ages of 6 and 59 months were fully protected with two high-dose vitamin A supplements. Vitamin A capsules cost about US$0.02. The capsules are easy to handle; they do not need to be stored in a refrigerator or vaccine carrier. When the correct dosage is given, vitamin A is safe and has no negative effect on [[Biology:Seroconversion|seroconversion]] rates for oral polio or measles vaccines. However, because the benefit of vitamin A supplements is transient, children need them regularly every four to six months. Since NIDs provide only one dose per year, NIDs-linked vitamin A distribution must be complemented by other programs to maintain vitamin A in children.<ref name="Distribution of vitamin A during national immunization days">{{cite web |url=https://www.who.int/vaccines-documents/DocsPDF/www9836.pdf |title=Distribution of vitamin A during national immunization days |access-date=3 March 2008 |archive-date=18 October 2012 |archive-url=https://web.archive.org/web/20121018045229/http://www.who.int/vaccines-documents/DocsPDF/www9836.pdf |url-status=dead }}</ref><ref name="WHO Vitamin A supplementation">{{cite web |url=https://www.who.int/vaccines/en/vitamina.shtml |title=WHO Vitamin A supplementation |access-date=3 March 2008 |archive-url=https://web.archive.org/web/20130125025617/http://www.who.int/vaccines/en/vitamina.shtml |archive-date=25 January 2013 |url-status=dead }}</ref> Maternal high supplementation benefits both mother and breast-fed infant: high-dose vitamin A supplementation of the lactating mother in the first month postpartum can provide the breast-fed infant with an appropriate amount of vitamin A through [[Biology:Breast milk|breast milk]]. However, high-dose supplementation of pregnant women should be avoided because it can cause [[Medicine:Miscarriage|miscarriage]] and birth defects.<ref name="pmid8463867">{{cite journal  |vauthors=Stoltzfus RJ, Hakimi M, Miller KW, etal |title=High dose vitamin A supplementation of breast-feeding Indonesian mothers: effects on the vitamin A status of mother and infant |journal=J. Nutr. |volume=123 |issue=4 |pages=666–675 |year=1993 |pmid=8463867 |doi=10.1093/jn/123.4.666|doi-access=free }}</ref>
* Food fortification is also useful for improving VAD. A variety of oily and dry forms of the retinol esters, retinyl acetates, and [[Chemistry:Retinyl palmitate|retinyl palmitate]] are available for [[Chemistry:Food fortification|food fortification]] of vitamin A. Margarine and [[Chemistry:Oil|oil]] are the ideal food vehicles for vitamin A fortification. They protect vitamin A from oxidation during storage and prompt absorption of vitamin A. Beta-carotene and [[Chemistry:Retinyl acetate|retinyl acetate]] or retinyl palmitate are used as a form of vitamin A for vitamin A fortification of fat-based foods. Fortification of sugar with retinyl palmitate as a form of vitamin A has been used extensively throughout Central America. Cereal flours, milk powder, and liquid milk are also used as food vehicles for vitamin A fortification.<ref name="isbn92-4-159401-2">{{cite book |vauthors = Allen L|title=Guidelines on Food Fortification With Micronutrients |publisher=World Health Organization |location=Geneva |year= 2006|isbn=92-4-159401-2}}</ref><ref name="isbn9251038848 ">{{cite book |author=Food and Agriculture Organization of the United Nations |title=Food Fortification: Tech & Quality Control (Food & Nutrition Papers) |publisher=Bernan Assoc|year= 1996|isbn=92-5-103884-8}}</ref>
* Separated from fortification via addition of synthetic vitamin A to foods, means of fortifying foods via [[Biology:Genetic engineering|genetic engineering]] have been explored. Research on rice began in 1982.<ref>[http://www.goldenrice.org/Content3-Why/why3_FAQ.php#Inventors FAQ: Who invented Golden Rice and how did the project start?] Goldenrice.org.</ref> The first field trials of golden rice cultivars were conducted in 2004.<ref>{{cite web|author=LSU AgCenter Communications|date=2004|title='Golden Rice' Could Help Reduce Malnutrition |url=http://www.lsuagcenter.com/news_archive/2004/October/Headline+News/Golden+Rice+Could+Help+Malnutrition.htm|url-status=dead|archive-url=https://web.archive.org/web/20070928171832/http://www.lsuagcenter.com/news_archive/2004/October/Headline%2BNews/Golden%2BRice%2BCould%2BHelp%2BMalnutrition.htm|archive-date=28 September 2007}}</ref> The result was "Golden Rice", a variety of ''[[Biology:Oryza sativa|Oryza sativa]]'' rice produced through genetic engineering to [[Biology:Biosynthesis|biosynthesize]] beta-carotene, a precursor of retinol, in the edible parts of rice.<ref>{{cite journal |vauthors=Kettenburg AJ, Hanspach J, Abson DJ, Fischer J |title=From disagreements to dialogue: unpacking the Golden Rice debate |journal=Sustain Sci |volume=13 |issue=5 |pages=1469–82 |date=2018 |pmid=30220919 |pmc=6132390 |doi=10.1007/s11625-018-0577-y |bibcode=2018SuSc...13.1469K |url=}}</ref><ref>{{cite journal |vauthors=Ye X, Al-Babili S, Klöti A, Zhang J, Lucca P, Beyer P, Potrykus I |title=Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm |journal=Science |volume=287 |issue=5451 |pages=303–5 |date=January 2000 |pmid=10634784 |doi=10.1126/science.287.5451.303 |bibcode=2000Sci...287..303Y |s2cid=40258379 |url=}}</ref> In May 2018, regulatory agencies in the United States, Canada, Australia and New Zealand had concluded that Golden Rice met food safety standards.<ref>{{Cite news|url=http://irri.org/news/media-releases/golden-rice-meets-food-safety-standards-in-three-global-leading-regulatory-agencies|title= Golden Rice meets food safety standards in three global leading regulatory agencies|work=International Rice Research Institute – IRRI|access-date=30 May 2018|language=en-gb}}</ref> On 21 July 2021, the Philippines became the first country to officially issue the biosafety permit for commercially propagating Golden Rice.<ref>{{Cite web| vauthors = Talavera C |title=Philippines OKs GMO 'golden rice' |url=https://www.philstar.com/headlines/2021/07/24/2114742/philippines-oks-gmo-golden-rice|access-date=21 August 2021|website=Philstar.com}}</ref><ref>{{Cite web|date=23 July 2021|title=Filipinos soon to plant and eat Golden Rice|url=https://www.philrice.gov.ph/filipinos-soon-to-plant-and-eat-golden-rice/|access-date=21 August 2021|website=Philippine Rice Research Institute|language=en-US}}</ref> In 2023, however, the Supreme Court of the Philippines ordered the [[Organization:Department of Agriculture (Philippines)|agriculture department]] to stop commercial propagation of golden rice in relation to a petition filed by MASIPAG (a group of farmers and scientists), who claimed that golden rice poses risk to the health of consumers and to the environment.<ref>{{Cite web |last=Ordoñez |first=John Victor D. |date=20 April 2023 |title=SC issues Writ of Kalikasan vs Golden Rice, Bt eggplant - BusinessWorld Online |website=BusinessWorld |url=https://www.bworldonline.com/top-stories/2023/04/20/517938/sc-issues-writ-of-kalikasan-vs-golden-rice-bt-eggplant/ |access-date=22 August 2023 |archive-url=https://web.archive.org/web/20230420164928/https://www.bworldonline.com/top-stories/2023/04/20/517938/sc-issues-writ-of-kalikasan-vs-golden-rice-bt-eggplant/ |archive-date=20 April 2023 }}</ref> Researchers at the U.S. [[Organization:Agricultural Research Service|Agricultural Research Service]] have been able to identify genetic sequences in corn that are associated with higher levels of beta-carotene, the precursor to vitamin A. They found that breeders can cross certain variations of corn to produce a crop with an 18-fold increase in beta-carotene.<ref>{{cite web|url= http://www.ars.usda.gov/is/pr/2010/100503.htm|title= A New Approach that Saves Eyesight and Lives in the Developing World| publisher= USDA Agricultural Research Service|date=May 2010|access-date=19 August 2010| archive-date= 3 March 2016 |archive-url= https://web.archive.org/web/20160303221401/http://www.ars.usda.gov/is/pr/2010/100503.htm| url-status= live}}</ref>
* Dietary diversification can also reduce risk of VAD. Non-animal sources of vitamin A like fruits and vegetables contain pro-vitamin A and account for greater than 80% of intake for most individuals in the developing world. The increase in consumption of vitamin A-rich foods of animal origin has beneficial effects on VAD.<ref name="titlechildinfo.org: Vitamin A Deficiency">{{cite web |url=http://www.childinfo.org/areas/vitamina/ |title=childinfo.org: Vitamin A Deficiency |access-date=14 March 2008|archive-url = https://web.archive.org/web/20080218161310/http://www.childinfo.org/areas/vitamina/ <!-- Bot retrieved archive --> |archive-date = 18 February 2008}}</ref>

==Global initiatives==
Global efforts to support national governments in addressing VAD are led by the Global Alliance for Vitamin A (GAVA), which is an informal partnership between Nutrition International, Helen Keller International, UNICEF, WHO, and CDC. About 75% of the vitamin A required for supplementation of preschool-aged children in low- and middle-income countries is supplied through a partnership between Nutrition International and UNICEF, with support from Global Affairs Canada.<ref name="who98">{{cite web|title=Micronutrient Deficiencies: Vitamin A|publisher=World Health Organization|url=https://www.who.int/nutrition/topics/vad/en/index.html|access-date=12 September 2019|archive-date=3 December 2013|archive-url=https://web.archive.org/web/20131203070728/http://www.who.int/nutrition/topics/vad/en/index.html|url-status=live}}</ref> An estimated 1.25 million deaths due to vitamin A deficiency have been averted in 40 countries since 1998.<ref name=who98/> In 2013, the prevalence of vitamin A deficiency was 29% in low-income and middle-income countries, remaining highest in [[Place:Sub-Saharan Africa|sub-Saharan Africa]] and [[Place:South Asia|South Asia]].<ref name="Stevens">{{cite journal | last1=Stevens | first1=Gretchen A | last2=Bennett | first2=James E | last3=Hennocq | first3=Quentin | last4=Lu | first4=Yuan | last5=De-Regil | first5=Luz Maria | last6=Rogers | first6=Lisa | last7=Danaei | first7=Goodarz | last8=Li | first8=Guangquan | last9=White | first9=Richard A | last10=Flaxman | first10=Seth R | last11=Oehrle | first11=Sean-Patrick | last12=Finucane | first12=Mariel M | last13=Guerrero | first13=Ramiro | last14=Bhutta | first14=Zulfiqar A | last15=Then-Paulino | first15=Amarilis | last16=Fawzi | first16=Wafaie | last17=Black | first17=Robert E | last18=Ezzati | first18=Majid | title=Trends and mortality effects of vitamin A deficiency in children in 138 low-income and middle-income countries between 1991 and 2013: a pooled analysis of population-based surveys | journal=The Lancet Global Health | volume=3 | issue=9 | year=2015 | issn=2214-109X | doi=10.1016/s2214-109x(15)00039-x | pages=e528–e536|pmid=26275329| doi-access=free | hdl=10044/1/48910 | hdl-access=free }}</ref> A 2017 review (updated in 2022) found that vitamin A supplementation in children five years old and younger in 70 countries was associated with a 12% reduction in [[Mortality rate|mortality rate]].<ref name=":2">{{Cite journal |last1=Imdad |first1=Aamer |last2=Mayo-Wilson |first2=Evan |last3=Haykal |first3=Maya R. |last4=Regan |first4=Allison |last5=Sidhu |first5=Jasleen |last6=Smith |first6=Abigail |last7=Bhutta |first7=Zulfiqar A. |date=16 March 2022 |title=Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age |journal=The Cochrane Database of Systematic Reviews |volume=2022 |issue=3 |pages=CD008524 |doi=10.1002/14651858.CD008524.pub4 |issn=1469-493X |pmc=8925277 |pmid=35294044}}</ref> The review reported that synthetic vitamin A supplementation may not be the best long‐term solution for vitamin A deficiency, but rather [[Chemistry:Food fortification|food fortification]], improved food distribution programs, and crop improvement, such as for fortified rice or vitamin A-rich [[Biology:Sweet potato|sweet potato]], may be more effective in eradicating vitamin A deficiency.<ref name=":2" />

==References==
{{Reflist}}

==Further reading==
* [http://www.unicef.org/publications/files/Vitamin_A_Supplementation.pdf UNICEF, Vitamin A Supplementation: A Decade of Progress, UNICEF, New York, 2007.]
* [http://www.unitedcalltoaction.org/documents/Investing_in_the_future.pdf Flour Fortification Initiative, GAIN, Micronutrient Initiative, USAID, The World Bank, UNICEF, Investing in the Future: A United Call to Action on Vitamin and Mineral Deficiencies, 2009.]
* [http://www.data.unicef.org/resources/improving-child-nutrition-the-achievable-imperative-for-global-progress, UNICEF, Improving Child Nutrition: The achievable imperative for global progress, UNICEF, New York, 2013.]

==External links==
* [https://www.nutritionintl.org/ Nutrition International]
* [http://www.gava.org Global Alliance for Vitamin A]
* [https://data.unicef.org/topic/nutrition/vitamin-a-deficiency/ UNICEF Data on Vitamin A Deficiency and Supplementation]
* [https://helenkellerintl.org/ Helen Keller International]
* [http://www.a2zproject.org A2Z]
* [https://web.archive.org/web/20070713142857/http://www.who.int/vmnis/vitamina/data/en/index.html World Health Organization Database on Vitamin A Deficiency]
* [https://www.iapb.org/learn/knowledge-hub/eye-conditions/vitamin-a-deficiency/ Vitamin A Deficiency] on IAPB

{{Nutritional pathology}}

{{DEFAULTSORT:Vitamin A Deficiency}}
[[Category:Vitamin deficiencies]]

{{Sourceattribution|Vitamin A deficiency}}