Carotene requires conversion to Retinoic acid and the other forms of retinol esters - some may not do this conversion well, as i found out from a gene test. Had no idea - i was munching carrots like they were going out of fashion!
BTW - raw carrot consumption contains MUCH less carotene than cooked carrots. Something like 10KG of raw carrot = 0.5kg cooked carrot carotene levels.
Liver consumption (as liver in all mammals stores vit A so it's good to eat it if you like it) can help with mild deficiency and to keep levels good.
I personally take liver oil, retinol to bypass the inadequate gene enzyme conversion of carotene to retinol.