Uvithamini A

UVitamin A uvithamini oncibilika emafutheni ogcinwa esibindini.

Kunezinhlobo ezimbili zikavithamini A ezitholakala ekudleni.

• I-vitamin A eyenziwe ngaphambilini itholakala emikhiqizweni yezilwane njengenyama, inhlanzi, izinkukhu, kanye nokudla okobisi.
• I-Provitamin A itholakala ekudleni okususelwa ezitshalweni ezifana nezithelo nemifino. Uhlobo oluvame kakhulu lwe-pro-vitamin A yi-beta-carotene.

UVitamin A uyatholakala nakwizithasiselo zokudla. Imvamisa iza ngesimo se-retinyl acetate noma i-retinyl palmitate (i-preformed vitamin A), i-beta-carotene (i-provitamin A) noma inhlanganisela ye-preformed ne-provitamin A.

UVitamin A usiza ukwakha nokugcina amazinyo aphilile, izicubu zamathambo nezithambile, ulwelwesi lwamafinyila, nesikhumba. Yaziwa nangokuthi i-retinol ngoba ikhiqiza ama-pigment ku-retina yeso.

UVitamin A ukhuthaza ukubona okuhle, ikakhulukazi ekukhanyeni okuphansi. Iphinde ibambe iqhaza ekukhulelweni nasekubeleni okunempilo.

Uvithamini A utholakala ngezindlela ezimbili:

• I-Retinol: I-Retinol iyindlela esebenzayo kavithamini A. Itholakala esibindini sesilwane, obisini lonke, nakokunye ukudla okuqinisiwe.
• I-Carotenoids: I-Carotenoids ingudayi ombala omnyama (izingulube). Zitholakala ekudleni kwezitshalo okungaphenduka kube uhlobo olusebenzayo lukavithamini A. Kunama-carotenoid angaphezu kwama-500 aziwayo. Enye ye-carotenoid enjalo yi-beta-carotene.

I-Beta-carotene iyi-antioxidant. Ama-antioxidants avikela amaseli emonakalweni odalwe yizinto ezibizwa ngama-radicals amahhala.

Ama-radicals wamahhala akholelwa ukuthi:

• Nikela ezifweni ezithile zesikhathi eside
• Dlala indima ekugugeni

Ukudla imithombo yokudla ye-beta-carotene kunganciphisa ingozi yomdlavuza.

Izengezo ze-beta-carotene azibonakali zinciphisa ingozi yomdlavuza.

Uvithamini A uvela emithonjeni yezilwane, njengamaqanda, inyama, ubisi oluqinile, ushizi, ukhilimu, isibindi, izinso, i-cod ne-halibut fish oil.

Kodwa-ke, eminingi yale mithombo, ngaphandle kwe-Vitamin A ene-skim milk eqinile, inamafutha amaningi ne-cholesterol egcwele.

Imithombo engcono kakhulu kavithamini A yile:

• Uwoyela we-cod wesibindi
• Amaqanda
• Izinhlamvu zasekuseni eziqinisiwe
• Ubisi olunamafutha oluqinile
• Imifino ewolintshi nephuzi nezithelo
• Eminye imithombo ye-beta-carotene efana ne-broccoli, isipinashi, nemifino eluhlaza kakhulu, eluhlaza

Ukujula kombala wesithelo noma imifino, kuphakamisa inani le-beta-carotene. Imithombo yemifino ye-beta-carotene ayinamafutha ne-cholesterol. Ukumuncwa kwabo kuyathuthuka uma le mithombo idliwa ngamafutha.

UKUPHELELWA:

Uma ungatholi uvithamini A owanele, usengozini enkulu yezinkinga zamehlo ezifana nalezi:

• Ubumpumputhe obuguqulwa ebusuku
• Umonakalo we-corneal ongaguquguquki owaziwa njenge-xerophthalmia

Ukuntuleka kukavithamini A kungaholela kwi-hyperkeratosis noma isikhumba esomile, esinamaxolo.

UKUTHOLA OKUPHAKATHI:

Uma uthola uvithamini A omningi kakhulu, ungagula.

• Imithamo emikhulu kavithamini A nayo ingadala ukukhubazeka kokuzalwa.
• Uvithamini A oyingozi kakhulu ubuthi buvame ukwenzeka lapho umuntu omdala ethatha u-vitamin A.
• Ubuthi obungapheli be-vitamin A bungavela kubantu abadala abahlala bethatha ngaphezu kwama-25,000 IU ngosuku.

Izingane nezingane zizwela kakhulu ku-vitamin A. Zingagula ngemuva kokuthatha imithamo emincane kavithamini A noma imikhiqizo equkethe uvithamini A efana ne-retinol (etholakala okhilimu besikhumba).

Inani elikhulu le-beta-carotene ngeke likugulise. Kodwa-ke, inani eliphakeme le-beta-carotene lingenza isikhumba siphuzi noma sibe-orange. Umbala wesikhumba uzobuyela kokujwayelekile uma wehlisa ukudla kwakho i-beta-carotene.

Indlela engcono yokuthola imfuneko yansuku zonke yamavithamini abalulekile ukudla izinhlobo ezahlukahlukene zezithelo, imifino, ukudla okobisi okuqinisiwe, imidumba (ubhontshisi omisiwe), udali, nezinhlamvu ezigcwele.

Ukudla Okunconywayo Kwabantu Abanovithamini A: I-Food and Nutrition Board ye-Institute of Medicine - Dietary Reference Intakes (DRIs)

Izinsana (ukudla okulingene)

• Izinyanga ezingu-0 kuya kwezingu-6: ama-micrograms angu-400 ngosuku (mcg / ngosuku)
• Izinyanga eziyi-7 kuya kwezingu-12: 500 mcg / ngosuku

I-Recommended Dietary Allowance (RDA) yamavithamini ingakanani ivithamini ngayinye abantu abaningi okufanele bayithole usuku ngalunye. I-RDA yamavithamini ingasetshenziswa njengezinjongo zomuntu ngamunye.

Izingane (RDA)

• Iminyaka eyi-1 kuye kwengu-3: 300 mcg / ngosuku
• Iminyaka emi-4 kuya kwengu-8: 400 mcg / ngosuku
• Iminyaka eyi-9 kuye kwengu-13: 600 mcg / ngosuku

Intsha kanye nabantu abadala (RDA)

• Abesilisa abaneminyaka engu-14 nangaphezulu: 900 mcg / ngosuku
• Abesifazane abaneminyaka engu-14 nangaphezulu: 700 mcg / ngosuku (kwabesifazane abaneminyaka engu-19 kuya kwengu-50, 770 mcg / ngosuku ngesikhathi sokukhulelwa kanye no-1,300 mcg / ngosuku ngesikhathi sokuncelisa ibele)

Ukuthi uvithamini ngamunye udinga kangakanani kuya ngeminyaka yakho nobulili bakho. Ezinye izinto, njengokukhulelwa nempilo yakho, nazo zibalulekile. Buza umhlinzeki wakho wezokunakekelwa kwempilo ukuthi imuphi umthamo olungele wena.

I-Retinol; I-retina; I-retinoic acid; AmaCarotenoids

• Inzuzo ka-Vitamin A.
• Umthombo ka-Vitamin A.

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URoss CA. Ukushoda kuka-Vitamin A nokuningi. Ku: Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Incwadi kaNelson Yezingane. Umhlaka 21. IPhiladelphia, PA: Elsevier; 2020: isahluko 61.

USalwen MJ. Amavithamini nezinto ezilandelwayo. Ku: McPherson RA, Pincus MR, abahleli. UHenry’s Clinical Diagnosis and Management by Laboratory Methods. Umhla ka-23. ISt Louis, MO: Elsevier; 2017: isahluko 26.

Ngakho-ke i-YT. Ukuntuleka kwezifo zesimiso sezinzwa. Ku: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, ama-eds. I-Neurology kaBradley ekwenziweni kwemitholampilo. Umhla wesi-7. IPhiladelphia, PA: Elsevier; 2016: isahluko 85.