Vitamin A je vitamin rozpustn\u00fd v tuc\u00edch, kter\u00fd m\u00e1 n\u011bkolik d\u016fle\u017eit\u00fdch funkc\u00ed v t\u011ble.
\nPom\u00e1h\u00e1 bu\u0148k\u00e1m norm\u00e1ln\u011b se mno\u017eit, proces zvan\u00fd bun\u011b\u010dn\u00e1 diferenciace.
\nJe nezbytn\u00fd, pro dobr\u00e9 vid\u011bn\u00ed. Prvn\u00edm p\u0159\u00edznakem nedostatku vitaminu A je \u010dasto slab\u00fd zrak v noci.
\nJe nevyhnutn\u00fd pro spr\u00e1vn\u00fd v\u00fdvoj embrya a plodu.
\nVitamin A pom\u00e1h\u00e1 udr\u017eovat zdravou sliznici, nos, vedlej\u0161\u00ed nosn\u00e9 dutiny, a \u00fasta zdrav\u00e1.<\/p>\n
Tak\u00e9 hraje roli p\u0159i:<\/p>\n
Vitamin A poch\u00e1z\u00ed ze dvou zdroj\u016f. Jedna skupina, tzv retinoidy, poch\u00e1z\u00ed z \u017eivo\u010di\u0161n\u00fdch zdroj\u016f a zahrnuje retinol. Druh\u00e1 skupina, tzv karotenoidy, poch\u00e1z\u00ed z rostlin a obsahuje beta-karoten. T\u011blo p\u0159em\u011b\u0148uje beta-karoten na vitamin A. Hlavn\u011b karotenoidy, v\u010detn\u011b lykopenu, luteinu a zeaxantuinu, maj\u00ed d\u016fle\u017eit\u00e9 biologick\u00e9 vlastnosti, v\u010detn\u011b procesu antioxidace a fotoprotektivn\u00ed aktivity.<\/p>\n
Mezi p\u0159\u00edznaky nedostatku vitaminu A se \u0159ad\u00ed:<\/p>\n
P\u0159i\u010dem\u017e vitamin A je nezbytn\u00fd pro dobr\u00e9 zdrav\u00ed, m\u016f\u017ee b\u00fdt tak\u00e9 toxick\u00fd ve vysok\u00fdch d\u00e1vk\u00e1ch. Nedoporu\u010duje se p\u0159ekra\u010dovat
\ndoporu\u010den\u00e9 denn\u00ed d\u00e1vky bez porady s l\u00e9ka\u0159em.<\/p>\n
P\u0159edepisovan\u00e9 kr\u00e9my a pr\u00e1\u0161ky, kter\u00e9 obsahuj\u00ed retinoidy, pom\u00e1haj\u00ed uklidnit t\u011b\u017ek\u00e9 akn\u00e9 a loupenku. Tak\u00e9 se osv\u011bd\u010duje pozitivn\u011b p\u0159i l\u00e9\u010db\u011b jin\u00fdch ko\u017en\u00edch poruch, nap\u0159\u00edklad bradavic a p\u0159ed\u010dasn\u00e9mu st\u00e1rnut\u00ed poko\u017eky ze slunce. Ned\u00e1vn\u00e9 studie ukazuj\u00ed, \u017ee lok\u00e1ln\u00ed aplikace spolu s antioxidanty mohou pomoci minimalizovat v\u00fdskyt jemn\u00fdch linek a vr\u00e1sek. Av\u0161ak, tyto l\u00e9ky vy\u017eaduj\u00ed p\u0159\u00edsn\u00fd dohled l\u00e9ka\u0159e. Isotretinoin (Accutane), \u00fastn\u00ed l\u00e9k na akn\u00e9, m\u016f\u017ee zp\u016fsobit velmi v\u00e1\u017en\u00e9 vedlej\u0161\u00ed \u00fa\u010dinky a nesm\u00ed b\u00fdt pou\u017e\u00edv\u00e1n u t\u011bhotn\u00fdch \u017een nebo \u017een v plodn\u00e9m v\u011bku, kter\u00e9 neu\u017e\u00edvaj\u00ed antikoncepci.<\/p>\n
Dostatek vitaminu A ve va\u0161\u00ed strav\u011b je nezbytn\u00fd pro dobr\u00e9 vid\u011bn\u00ed. V\u00fdzkum ukazuje, \u017ee lid\u00e9, kte\u0159\u00ed jed\u00ed v\u00edce potravin s obsahem vitaminu A maj\u00ed men\u0161\u00ed pravd\u011bpodobnost vzniku v\u011bkem podm\u00edn\u011bn\u00e9 makul\u00e1rn\u00ed degenerace (VPMD). Krom\u011b toho velk\u00e1 popula\u010dn\u00ed studie zjistila, \u017ee lid\u00e9, kte\u0159\u00ed p\u0159ijali stravou vysok\u00e9 hladiny vitaminu A m\u011bli ni\u017e\u0161\u00ed riziko vzniku \u0161ed\u00e9ho z\u00e1kalu. V\u011bdci ale nev\u00ed, zda u\u017e\u00edv\u00e1n\u00ed dopl\u0148k\u016f vitaminu A bude fungovat stejn\u00fdm zp\u016fsobem. Dopl\u0148ky s vitaminem A mohou m\u00edrn\u011b pomoci zpomalit \u0161kody
\nzp\u016fsoben\u00e9 retinitis pigmentosa, d\u011bdi\u010dnou chorobou, kter\u00e1 zp\u016fsobuje \u0161patn\u00e9 no\u010dn\u00ed vid\u011bn\u00ed. Studie v\u0161ak pou\u017e\u00edvala vysok\u00e9 d\u00e1vky, kter\u00e9 mohou b\u00fdt toxick\u00e9.<\/p>\n
Pro d\u011bti, kter\u00e9 maj\u00ed deficit vitaminu A, mohou dopl\u0148ky sn\u00ed\u017eit z\u00e1va\u017enost a komplikace spalni\u010dek. D\u011bti, kter\u00e9 maj\u00ed nedostatek vitaminu A jsou n\u00e1chyln\u011bj\u0161\u00ed k infekc\u00edm, v\u010detn\u011b spalni\u010dek. V oblastech sv\u011bta, kde je nedostatek vitaminu A um\u00edr\u00e1 a\u017e 1% d\u011bt\u00ed ze spalni\u010dkami.<\/p>\n
Zda vitamin A m\u016f\u017ee sn\u00ed\u017eit riziko rakoviny, nen\u00ed jasn\u00e9. Zd\u00e1 se, \u017ee lid\u00e9, kte\u0159\u00ed jed\u00ed zdravou stravu s dostatkem beta-karotenu a dal\u0161\u00edch karotenoid\u016f z ovoce a zeleniny, maj\u00ed ni\u017e\u0161\u00ed riziko vzniku n\u011bkter\u00fdch druh\u016f rakoviny, jako nap\u0159\u00edklad:<\/p>\n
N\u011bkter\u00e9 laboratorn\u00ed studie nazna\u010duj\u00ed, \u017ee vitamin A a karotenoidy m\u016f\u017eou pom\u00e1hat v boji proti n\u011bkter\u00fdm druh\u016fm rakoviny.\u00a0N\u011bkolik studi\u00ed uk\u00e1zalo, \u017ee u\u017e\u00edv\u00e1n\u00ed dopl\u0148k\u016f vitaminu A pom\u016f\u017ee p\u0159i prevenci, \u010di l\u00e9\u010db\u011b rakoviny. Na druh\u00e9 stran\u011b bylo u\u017e\u00edv\u00e1n\u00ed beta-karotenu nebo vitaminov\u00fdch dopl\u0148k\u016f spojeno s vy\u0161\u0161\u00edm rizikem rakoviny plic u lid\u00ed, kte\u0159\u00ed kou\u0159\u00ed nebo pij\u00ed alkohol. Nicm\u00e9n\u011b, v\u011bdci tvrd\u00ed, \u017ee je pot\u0159eba v\u00edce studi\u00ed na potvrzen\u00ed t\u00e9to teorie.<\/p>\n
V\u011bdci tak\u00e9 skoumaj\u00ed retinoidy, syntetickou formu vitaminu A, p\u0159i rakovin\u011b k\u016f\u017ee. Lid\u00e9 s ur\u010dit\u00fdmi typy rakoviny k\u016f\u017ee, maj\u00ed ni\u017e\u0161\u00ed hladinu vitaminu A a beta-karotenu v krvi. Nicm\u00e9n\u011b samotn\u00e1 studie, m\u011bla sm\u00ed\u0161en\u00e9 v\u00fdsledky.<\/p>\n
Vitamin A ve form\u011b retinylpalmit\u00e1tu lze nal\u00e9zt v:<\/p>\n
V\u011bt\u0161ina\u00a0tmav\u011b zelen\u00e9 listov\u00e9 zeleniny i\u00a0syt\u011b \u017elut\u00e9 \/ oran\u017eov\u00e9 zeleniny a ovoce, mrkev, d\u00fdn\u011b, meru\u0148ky, broskve, a mango, obsahuj\u00ed zna\u010dn\u00e9 mno\u017estv\u00ed beta-karotenu. T\u00edm, \u017ee j\u00edte tyto na beta-karoten bohat\u00e9 potraviny, m\u016f\u017eete zv\u00fd\u0161it hladinu vitaminu A v t\u011ble.<\/p>\n
Dopl\u0148ky vitaminu A jsou k dispozici bu\u010f jako retinol nebo retinylpalmit\u00e1t.
\nTablety nebo kapsle, jsou k dispozici v r\u016fzn\u00fdch d\u00e1vk\u00e1ch. Tolerovateln\u00e1 horn\u00ed hranice, nebo bezpe\u010dn\u00e1 horn\u00ed mez je 10000 IU.
\nV\u011bt\u0161ina multivitam\u00edn\u016f obsahuje doporu\u010den\u00fd denn\u00ed p\u0159\u00edjem (RDA) vitam\u00ednu A.
\nNa rozd\u00edl od vitaminu A, beta-karoten se v t\u011ble nehromad\u00ed. Nicm\u00e9n\u011b, existuj\u00ed ur\u010dit\u00e9 d\u016fkazy, \u017ee vysok\u00e9 d\u00e1vky beta-karotenu m\u016f\u017eou n\u00e9st jist\u00e9 riziko. Pora\u010fte se se sv\u00fdm l\u00e9ka\u0159em, ne\u017e za\u010dnete p\u0159ekra\u010dovat doporu\u010den\u00e9 mno\u017estv\u00ed.<\/p>\n
Vitamin A se vst\u0159eb\u00e1va s tuky ve strav\u011b. U\u017e\u00edvejte ho proto s j\u00eddlem.
\nStudie \u010dasto pracuj\u00ed s vysok\u00fdmi d\u00e1vkamy vitaminu A. Av\u0161ak tyto vysok\u00e9 d\u00e1vky mohou b\u00fdt toxick\u00e9. L\u00e9ka\u0159 by m\u011bl sledovat ka\u017edou terapii s vysok\u00fdmi d\u00e1vkami (jak\u00e1koli d\u00e1vka bl\u00ed\u017e\u00edc\u00ed se \u00farovni 10,000 IU pro dosp\u011bl\u00e9ho, nebo nad doporu\u010den\u00e9 denn\u00ed d\u00e1vky pro d\u00edt\u011b).<\/p>\n
Denn\u00ed p\u0159\u00edjmi vitam\u00ednu A jsou n\u00e1sleduj\u00edc\u00ed: Dosp\u011bl\u00fd<\/strong> P\u0159\u00edjem velk\u00e9ho mno\u017estv\u00ed vitaminu A v t\u011bhotenstv\u00ed, m\u016f\u017ee zp\u016fsobit z\u00e1va\u017en\u00e9 vrozen\u00e9 vady. Proto\u017ee v\u0161echny prenat\u00e1ln\u00ed vitaminy obsahuj\u00ed vitamin A, nem\u011bli byste jej proto p\u0159ij\u00edmat z\u00e1rove\u0148 samostatn\u011b. Syntetick\u00fd vitamin A m\u016f\u017ee zp\u016fsobit vrozen\u00e9 vady. Vitamin A z potravin je pova\u017eov\u00e1n za bezpe\u010dn\u00fd. Ale p\u0159\u00edjem m\u016f\u017eete zv\u00fd\u0161it i dopl\u0148ky. Pro dosp\u011bl\u00e9, od 19 let, je tolerovateln\u00e1 horn\u00ed mez pro vitamin A 10000 IU denn\u011b. Pokud se l\u00e9\u010d\u00edte s n\u011bkter\u00fdm z n\u00e1sleduj\u00edc\u00edch l\u00e9k\u016f, nem\u011bli byste br\u00e1t vitamin A bez porady se sv\u00fdm l\u00e9ka\u0159em: Antacida<\/strong>: Jedna studie nazna\u010duje, \u017ee kombinace vitaminu A s antacidem, m\u016f\u017ee b\u00fdt \u00fa\u010dinn\u011bj\u0161\u00ed ne\u017e samotn\u00e9 antacidum p\u0159i hojen\u00ed v\u0159ed\u016f. Tretinoin (Retin-A), se obvykle p\u0159edepisuje jako ple\u0165ov\u00fd kr\u00e9m, k l\u00e9\u010db\u011b akn\u00e9 nebo redukci vr\u00e1sek, a nen\u00ed tak koncentrovan\u00fd jako jin\u00e9 retinoidy. I p\u0159esto se doporu\u010duje, aby ste se vyhnuly p\u0159ij\u00edm\u00e1n\u00ed dopl\u0148k\u016f vitaminu A p\u0159i pou\u017e\u00edv\u00e1n\u00ed Retin-A.<\/p>\n <\/p>\n zdroj: www.umm.edu<\/p>\n","protected":false},"excerpt":{"rendered":" Vitamin A (retinol) Vitamin A je vitamin rozpustn\u00fd v tuc\u00edch, kter\u00fd m\u00e1 n\u011bkolik d\u016fle\u017eit\u00fdch funkc\u00ed v t\u011ble.<\/p>\n<\/div>","protected":false},"author":1,"featured_media":1167,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19],"tags":[88,92,112,130,119],"class_list":["post-1161","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-vitaminy-a-mineraly","tag-prevence","tag-rakovina","tag-tuky","tag-vitamin-a","tag-vitaminy"],"views":5851,"_links":{"self":[{"href":"https:\/\/potravinyx.cz\/index.php?rest_route=\/wp\/v2\/posts\/1161","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/potravinyx.cz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/potravinyx.cz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/potravinyx.cz\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/potravinyx.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1161"}],"version-history":[{"count":0,"href":"https:\/\/potravinyx.cz\/index.php?rest_route=\/wp\/v2\/posts\/1161\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/potravinyx.cz\/index.php?rest_route=\/wp\/v2\/media\/1167"}],"wp:attachment":[{"href":"https:\/\/potravinyx.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1161"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/potravinyx.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1161"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/potravinyx.cz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1161"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nD\u011bti<\/strong>
\nKojenci, narozen\u00ed do 6 m\u011bs\u00edc\u016f: 400 mcg
\nKojenci, 7 a\u017e 12 m\u011bs\u00edc\u016f: 500 mcg
\nD\u011bti, 1 do 3 roky: 300 mcg
\nD\u011bti od 4 do 8 let: 400 mcg
\nD\u011bti, 9 a\u017e 13 let: 600 mcg
\nBoys, 14 a\u017e 18 let: 900 mcg
\nD\u00edvky, 14 a\u017e 18 let: 700 mcg<\/p>\n
\nMu\u017ei, 19 let a star\u0161\u00ed: 900 mcg
\n\u017deny, 19 let a star\u0161\u00ed: 700 mcg
\nT\u011bhotn\u00e9 \u017eeny, 14 a\u017e 18 let: 750 mcg
\nT\u011bhotn\u00e9 \u017eeny, 19 let a star\u0161\u00ed: 770 mcg
\nKoj\u00edc\u00ed \u017eeny, 14 a\u017e 18 let: 1.200 mcg
\nKoj\u00edc\u00ed \u017eeny, 19 let a star\u0161\u00edch: 1.300 mcg<\/p>\nOpatrn\u011b<\/h3>\n
\n\u017deny, kter\u00e9 jsou t\u011bhotn\u00e9 nebo se sna\u017e\u00ed ot\u011bhotn\u011bt, by nem\u011bli p\u0159ij\u00edmat tuto formu vitaminu A.
\nP\u0159\u00edli\u0161n\u00e9 u\u017e\u00edv\u00e1n\u00ed vitaminu A je toxick\u00e9 a m\u016f\u017ee zp\u016fsobit selh\u00e1n\u00ed jater, dokonce i smrt. P\u0159\u00edznaky toxicity vitam\u00ednem A zahrnuj\u00ed:<\/p>\n\n
\nLid\u00e9, kte\u0159\u00ed trp\u00ed onemocn\u011bn\u00edm jater nebo diabetem by nem\u011bli u\u017e\u00edvat dopl\u0148ky vitaminu A bez dohledu sv\u00e9ho l\u00e9ka\u0159e.
\nKu\u0159\u00e1ci a lid\u00e9, kte\u0159\u00ed pij\u00ed velk\u00e9 mno\u017estv\u00ed alkoholu nesm\u00ed u\u017e\u00edvat beta-karotenov\u00e9 dopl\u0148ky.
\nJak vitamin A tak i beta-karoten m\u016f\u017eou zv\u00fd\u0161it hladinu triglycerid\u016f, tedy tuku v krvi. Mohou dokonce zvy\u0161it riziko \u00famrt\u00ed u lid\u00ed se srde\u010dn\u00edm onemocn\u011bn\u00edm, zejm\u00e9na u ku\u0159\u00e1k\u016f.<\/p>\nMo\u017en\u00e9 interakce<\/h3>\n
\nAntibiotika tetracyklin:<\/strong> Lid\u00e9, kte\u0159\u00ed berou typ antibiotik zvan\u00fdch tetracykliny a tak\u00e9 berou vysok\u00e9 d\u00e1vky vitam\u00ednu A mohou b\u00fdt ohro\u017eeni stavem zvan\u00fdm intrakrani\u00e1ln\u00ed hypertenze, co\u017e je n\u00e1r\u016fst tlaku tekutiny mozku.\u00a0Tetracykliny zahrnuj\u00ed:<\/p>\n\n
\nAntikoagulanty (l\u00e9ky na \u0159ed\u011bn\u00ed krve)<\/strong>: Dlouhodob\u00e9 u\u017e\u00edv\u00e1n\u00ed vitam\u00ednu A nebo p\u0159i u\u017e\u00edv\u00e1n\u00ed vysok\u00fdch d\u00e1vek, m\u016f\u017ee\u00a0zv\u00fd\u0161it riziko krv\u00e1cen\u00ed u pacient\u016f u\u017e\u00edvaj\u00edc\u00edch l\u00e9ky na sni\u017een\u00ed sr\u00e1\u017eenlivosti krve, zejm\u00e9na warfarin (kumarin). Pora\u010fte se se sv\u00fdm l\u00e9ka\u0159em, ne\u017e za\u010dnete dopl\u0148ovat vitamin A.
\nL\u00e9ky ke sn\u00ed\u017een\u00ed hladiny cholesterolu (sekvestranty \u017elu\u010dov\u00fdch kyselin)<\/strong>: L\u00e9ky, cholestyramin (Questram) a kolestipol (Colestid) m\u016f\u017eou sn\u00ed\u017eit va\u0161i schopnost absorbovat vitamin A a v\u00e9st ke sn\u00ed\u017een\u00ed hladiny v t\u011ble. Ve vod\u011b rozpustn\u00e1 forma vitaminu A m\u016f\u017ee pomoci. Dal\u0161\u00ed t\u0159\u00edda l\u00e9k\u016f na sn\u00ed\u017een\u00ed cholesterolu zvan\u00e9 statiny, m\u016f\u017ee ve skute\u010dnosti zv\u00fd\u0161it hladiny vitaminu A v krvi.
\nDoxorubicin<\/strong>: Doxorubicin je l\u00e9k pou\u017e\u00edvan\u00fd k l\u00e9\u010db\u011b rakoviny. Studie nazna\u010duj\u00ed, \u017ee vitamin A m\u016f\u017ee zlep\u0161it p\u016fsoben\u00ed doxorubicinu. Je v\u0161ak zapot\u0159eb\u00ed dal\u0161\u00edho v\u00fdzkumu.
\nL\u00e9ky na l\u00e9\u010dbu jater<\/strong>: Vysok\u00e9 d\u00e1vky vitam\u00ednu A spolu s n\u011bkter\u00fdmi dal\u0161\u00edmi l\u00e9ky, kter\u00e9 jsou zpracov\u00e1v\u00e1ny v j\u00e1trech, m\u016f\u017eou zp\u016fsobit po\u0161kozen\u00ed jater nebo dokonce selh\u00e1n\u00ed. Jsou to hlavn\u00e9 l\u00e9ky obsahuj\u00ed acetaminofen (Tylenol), karbamazepin (Tegretol), isoniazid a methotrex\u00e1t. Pokud u\u017e\u00edv\u00e1te tyto l\u00e9ky na p\u0159edpis, pora\u010fte se se sv\u00fdm l\u00e9ka\u0159em, ne\u017e za\u010dnete br\u00e1t vitamin A.
\nNeomycin (Mycifradin)<\/strong>: Toto antibiotikum m\u016f\u017ee sn\u00ed\u017eit schopnost t\u011bla absorbovat vitam\u00edn A, a to zejm\u00e9na pokud je u\u017e\u00edv\u00e1no ve velk\u00fdch d\u00e1vk\u00e1ch.
\nRetinoidy<\/strong>: Tyto l\u00e9ky jsou syntetick\u00e1 forma vitaminu A a n\u011bkdy jsou p\u0159edeps\u00e1ny ve vysok\u00fdch d\u00e1vk\u00e1ch. Lid\u00e9, kte\u0159\u00ed berou retinoidy by nem\u011bli u\u017e\u00edvat dal\u0161\u00ed dopl\u0148ky s vitaminem A. Krom\u011b toho tyto l\u00e9ky mohou zp\u016fsobit v\u00e1\u017en\u00e9 vrozen\u00e9 vady. \u017deny v plodn\u00e9m v\u011bku mus\u00ed m\u00edt dva negativn\u00ed t\u011bhotensk\u00e9 testy a b\u00fdt na dvou form\u00e1ch antikoncepce p\u0159ed p\u0159ijet\u00edm t\u011bchto l\u00e9k\u016f.\u00a0Retinoidy obsahuj\u00ed:<\/p>\n\n