Servallos NJ (20 April 2023). "SC issues writ vs GMO golden rice, eggplant". Philippine Star . Retrieved 22 September 2023. In addition to retinol, retinal and retinoic acid, there are plant-, fungi- or bacteria-sourced carotenoids which can be metabolized to retinol, and are thus vitamin A vitamers. [11]

Vitamin A deficiency is common in developing countries, especially in Sub-Saharan Africa and Southeast Asia. Deficiency can occur at any age but is most common in pre-school age children and pregnant women, the latter due to a need to transfer retinol to the fetus. Vitamin A deficiency is estimated to affect approximately one-third of children under the age of five around the world, resulting in hundreds of thousands of cases of blindness and deaths from childhood diseases because of immune system failure. [9] Reversible night blindness is an early indicator of low vitamin A status. Plasma retinol is used as a biomarker to confirm vitamin A deficiency. Breast milk retinol can indicate a deficiency in nursing mothers. Neither of these measures indicates the status of liver reserves. [5]

Key facts

In addition to the approved use for treating acne vulgaris, researchers have investigated off-label applications for dermatological conditions, such as rosacea, psoriasis, and other conditions. [85] Rosacea was reported as responding favorably to doses lower than used for acne. Isotretinoin in combination with ultraviolet light was shown affective for treating psoriasis. Isotretinoin in combination with injected interferon-alpha showed some potential for treating genital warts. Isotretinoin in combination with topical fluorouracil or injected interferon-alpha showed some potential for treating precancerous skin lesions and skin cancer. [85] Topical retinoic acid and retinol [ edit ] Retinoids: Tretinoin is all-trans-retinoic acid; initial tradename: Retin-A. Isotretinoin is 13- cis-retinoic acid; initial tradename: Accutane. Etretinate and Acitretin, its non-esterified metabolite, are used orally to treat severe psoriasis. [12]

a b c d Whitcher JP, Srinivasan M, Upadhyay MP (2001). "Corneal blindness: a global perspective". Bulletin of the World Health Organization. 79 (3): 214–221. PMC 2566379. PMID 11285665. Janeway C, Travers P, Walport M, Shlomchik M (2001). Immunobiology (5thed.). New York and London: Garland Science. ISBN 0-8153-4101-6. Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies" (PDF). European Food Safety Authority (EFSA). 2017.

Carotenoid synthesis takes place in plants, certain fungi, and bacteria. Structurally carotenes are tetraterpenes, meaning that they are synthesized biochemically from four 10-carbon terpene units, which in turn were formed from eight 5-carbon isoprene units. Intermediate steps are the creation of a 40-carbon phytoene molecule, conversion to lycopene via desaturation, and then creation of ionone rings at both ends of the molecule. β-carotene has a β-ionone ring at both ends, meaning that the molecule can be divided symmetrically to yield two retinol molecules. α-Carotene has a β-ionone ring at one end and an Ɛ-ionone ring at the other, so it has half the retinol conversion capacity. [11] Vitamin A biosynthesis from β-carotene Publishing, Harvard Health (9 June 2009). "Listing of vitamins". Harvard Health . Retrieved 12 May 2020. Vitamin A deficiency (VAD) has been linked to compromised resistance to infectious diseases. [32] [33] In countries where early childhood VAD is common, vitamin A supplementation public health programs initiated in the 1980s were shown to reduce the incidence of diarrhea and measles, and all-cause mortality. [22] [34] [35] VAD also increases the risk of immune system over-reaction, leading to chronic inflammation in the intestinal system, stronger allergic reactions and autoimmune diseases. [32] [33] [36]

Carotenoderma, also referred to as carotenemia, is a benign and reversible medical condition where an excess of dietary carotenoids results in orange discoloration of the outermost skin layer. It is associated with a high blood β-carotene value. This can occur after a month or two of consumption of beta-carotene rich foods, such as carrots, carrot juice, tangerine juice, mangos, or in Africa, red palm oil. β-carotene dietary supplements can have the same effect. The discoloration extends to palms and soles of feet, but not to the white of the eye, which helps distinguish the condition from jaundice. [51] Consumption of greater than 30mg/day for a prolonged period has been confirmed as leading to carotenemia. [11] [52] U.S. labeling [ edit ] In 1967, George Wald, Ragnar Granit and Haldan Keffer Hartline were awarded the Nobel Prize in Physiology and Medicine "...for their discoveries concerning the primary physiological and chemical visual processes in the eye." Wald's contribution was discovering the role vitamin A had in the process. [35] [39] History of promotional marketing

In setting human nutrient guidelines, government organizations do not necessarily agree on amounts needed to avoid deficiency or maximum amounts to avoid the risk of toxicity. [57] [11] [58] For example, for vitamin C, recommended intakes range from 40mg/day in India [63] to 155mg/day for the European Union. [64] The table below shows U.S. Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamins, PRIs for the European Union (same concept as RDAs), followed by what three government organizations deem to be the safe upper intake. RDAs are set higher than EARs to cover people with higher than average needs. Adequate Intakes (AIs) are set when there is not sufficient information to establish EARs and RDAs. Governments are slow to revise information of this nature. For the U.S. values, with the exception of calcium and vitamin D, all of the data date to 1997–2004. [65]

Duester G (September 2008). "Retinoic acid synthesis and signaling during early organogenesis". Cell. 134 (6): 921–931. doi: 10.1016/j.cell.2008.09.002. PMC 2632951. PMID 18805086. a b "Vitamin A: Fact Sheet for Health Professionals". National Institute of Health: Office of Dietary Supplements. 5 June 2013. Archived from the original on 23 September 2009 . Retrieved 3 August 2013. a b Funk, Casimir (1912). "The etiology of the deficiency diseases. Beri-beri, polyneuritis in birds, epidemic dropsy, scurvy, experimental scurvy in animals, infantile scurvy, ship beri-beri, pellagra". Journal of State Medicine. 20: 341–68. The word "vitamine" is coined on p. 342: "It is now known that all these diseases, with the exception of pellagra, can be prevented and cured by the addition of certain preventative substances; the deficient substances, which are of the nature of organic bases, we will call "vitamines"; and we will speak of a beri-beri or scurvy vitamine, which means a substance preventing the special disease." Animal research (on mice), which is pre-clinical, also found Retinoid acid, the bioactive metabolite of vitamin A, to have an effect on brain areas responsible for memory and learning. [104] Cancer [ edit ]

Shabtai Y, Fainsod A (April 2018). "Competition between ethanol clearance and retinoic acid biosynthesis in the induction of fetal alcohol syndrome". Biochemistry and Cell Biology = Biochimie et Biologie Cellulaire. 96 (2): 148–160. doi: 10.1139/bcb-2017-0132. PMID 28982012. Akhtar S, Ahmed A, Randhawa MA, Atukorala S, Arlappa N, Ismail T, Ali Z (December 2013). "Prevalence of vitamin A deficiency in South Asia: causes, outcomes, and possible remedies". Journal of Health, Population, and Nutrition. 31 (4): 413–423. doi: 10.3329/jhpn.v31i4.19975. PMC 3905635. PMID 24592582. a b Gratzer W (2006). "9. The quarry run to earth". Terrors of the table: the curious history of nutrition. Oxford: Oxford University Press. ISBN 978-0199205639 . Retrieved 5 November 2015. These carotenoids include beta-carotene and alpha-carotene, which are collectively known as provitamin A.