Tsuas yog tus txhaj tshuaj tiv thaiv tuaj yeem tiv thaiv tau zoo qhua pias. Hauv cov neeg tsis muaj kev tiv thaiv kab mob, zam kev sib cuag nrog cov neeg mob yog qhov tseem ceeb. Nws kuj tseem tuaj yeem txhim kho koj lub cev tiv thaiv kab mob. Raws li peb cov kev tshawb fawb, tsis muaj kev kho mob ib txwm muaj pov thawj los kho tus mob qhua pias.

Vitamin A yog ib qho tseem ceeb vitamin, muab los ntawm cov khoom noj thiab tshwj xeeb cov khoom ntawm cov tsiaj keeb kwm (lub siab, offal, tag nrho cov mis nyuj, butter, thiab lwm yam). Ntau qhov kev tshawb fawb hauv cov teb chaws tsim kho tau pom tias kev ntxiv cov vitamin A tuaj yeem txo qhov kev tuag ntawm cov menyuam yaus hnub nyoog 6 txog 59 lub hlis, tshwj xeeb los ntawm kev txo qis kev pheej hmoo ntawm raws plab.⁷. Lub Koom Haum Saib Xyuas Kev Noj Qab Haus Huv Ntiaj Teb (WHO) pom zoo "tswj hwm rau ib tus menyuam twg uas muaj mob qhua pias ob koob tshuaj vitamin A ntxiv 24 teev sib nrug" txhawm rau txo qhov kev pheej hmoo ntawm qhov muag puas thiab dig muag. Kev tswj hwm cov vitamin A tseem yuav txo qis kev tuag los ntawm 50% (txo qis kev mob ntsws, mob ntsws thiab mob raws plab). Xyoo 2005, kev sib sau ua ke ntawm 8 txoj kev tshawb fawb, koom nrog 429 tus menyuam hnub nyoog qis dua 15 xyoos, tau lees paub tias kev tswj hwm ob koob tshuaj vitamin A siab ua rau cov menyuam yaus hnub nyoog qis dua ob xyoos uas tau cog qoob loo tuag.⁸.