Iyini i-vitamin D?
Iyivithamini encibilika emafutheni ekhiqizwa kakhulu ngesikhumba uma ivezwa emisebeni ye-ultraviolet B (UVB). Idlala indima ebalulekile empilweni yamathambo, amasosha omzimba kanye nokwakheka kwe-calcium emzimbeni.
Ubudlelwano phakathi kwemisebe ye-UV ne-vitamin D
Imisebe ye-UVB iwumthombo oyinhloko wokwenziwa kwevithamini D.
Uma isikhumba sesivele sitholakale ku-UVB, singakhiqiza i-vitamin D3 (cholecalciferol) ngokusebenzisa izandulela ze-cholesterol.
1. Imisebe ye-UVB Ibangela Ukwenziwa Kwevithamini D
Isikhumba siqukethe i-cholesterol derivative ebizwa ngokuthi i-7-dehydrocholesterol.
Uma ubhekene nemisebe ye-UVB (ubude be-wavelength 290)–315 nm), le nhlanganisela iguqulwa ibe yi-previtamin D₃, bese i-isomerized ngokushisa ibe yi-vitamin D₃(i-cholecalciferol).
I-Vitamin D₃ithuthwa iye esibindini nasezinso, lapho iguqulwa khona ibe yisimo sayo esisebenzayo, i-calcitriol (1,25-dihydroxyvitamin D).
2. Izici Ezithinta Ukukhiqizwa Kwevithamini D
Ukushintsha umbala wesikhumba: Isikhumba esimnyama (i-melanin ephezulu) sinciphisa ukumuncwa kwe-UVB, okudinga ukuchayeka elangeni isikhathi eside.
I-Latitude kanye nesizini: Ukuqina kwe-UVB kuphansi ebusika kanye nasezindaweni eziphakeme, okunciphisa ukwakheka kwe-vitamin D.
Isikhathi sosuku: Emini ilanga (10 ekuseni)–3 PM) inikeza ukukhanya okunamandla kakhulu kwe-UVB.
Ubudala: Abantu abadala bakhiqiza i-vitamin D encane ngenxa yesikhumba esincane.
Ukusetshenziswa kwe-sunscreen: I-SPF engaphezu kuka-30 ingavimba u-~95% we-UVB, okunciphisa ukwakheka kwe-vitamin D.
3. Izinzuzo zeVithamini D
Impilo yamathambo: Ikhuthaza ukumuncwa kwe-calcium, ivimbele ama-rickets (ezinganeni) kanye ne-osteomalacia (kwabantu abadala).
umsebenzi we-mmune: Usekela ukulawulwa kwamasosha omzimba futhi kunganciphisa izingozi zokutheleleka.
Ukulawulwa kwemizwa: Kuhlobene nokukhiqizwa kwe-serotonin, okungenzeka kuthuthukise impilo yengqondo.
4. Izingozi Zokuchayeka Ema-UV Kakhulu
Ukulimala kwesikhumba: Imisebe ye-UV ibangela ukushiswa yilanga, ukuguga ngaphambi kwesikhathi, kanye nokuguquka kwe-DNA.
Umdlavuza wesikhumba: Ukuchayeka isikhathi eside emisebeni ye-UV kwandisa ingozi yomdlavuza wesikhumba we-melanoma kanye nomdlavuza wesikhumba ongeyona i-melanoma.
Ubuthi be-Vitamin D: I-vitamin D eningi (ngokuvamile evela ezithasiselo, hhayi elangeni) ingaholela ku-hypercalcemia.
5. Ukulinganisela Ukuchayeka Elangeni Nokuphepha
Ukuchayeka isikhathi esifushane, njalo: 10–Imizuzu engama-30 yelanga lasemini (izingalo/imilenze iveziwe, akukho zivikelo zelanga) 2–Izikhathi ezintathu ngesonto zivame ukwanele ukwenziwa kwe-vitamin D (kuyahlukahluka ngohlobo lwesikhumba nendawo).
Imithombo yokudla: Izinhlanzi ezinamafutha (i-salmon, i-mackerel), ubisi oluqinisiwe, kanye nezithasiselo kusiza ekugcineni amazinga.
Isivikelo: Sebenzisa isivikelo selanga ngemva kokuchayeka okokuqala ukuze uvimbele ukulimala kwesikhumba.
Ingabe imishini yokushiswa kwesikhumba inalo msebenzi?
Imishini eminingi yokushiswa kwesikhumba ethengiswayo isebenzisa i-UVA kune-UVB. I-UVA ingena ngokujulile, kodwa ayidlali indima ekwakhiweni kwe-vitamin D.
Izifundo zithole ukuthi, ngisho noma kukhona inani elincane le-UVB, umthamo uphakeme kakhulu kunalowo otholakala elangeni lemvelo futhi umonakalo ongaba khona esikhumbeni mkhulu.
Ezinye izindlela eziphephile:
Ukuchayeka elangeni: imizuzu eyi-10-15 yokuchayeka ebusweni nasezingalweni nsuku zonke.
Ukudla: inhlanzi, izikhupha zamaqanda kanye nobisi oluqinisiwe.
Izithasiselo: Izithasiselo ze-Vitamin D3 kufanele zithathwe ngaphansi kokuqashwa ngudokotela.