What is the right supplementation ratio of Vitamin D3 to Vitamin A?

The right ratio is probably the one found in various liver oils. For instance, see details on cod liver oil: http://www.wolframalpha.com/input/?i=100ml+cod+liver+oil vitamin D | 9214   IU vitamin A | 92143 IU So as you can see you probably need 10x vitamin A more then vitamin D. Beta carotene is not good alternative to animal vitamin A (retynol). Its probably not harmful as suggested above because evidence for that is limited (and suggested only for smokers, not for non-smokers at all). International Vitamin A Council (IVAC) was suggesting ~25000 IU as a daily dose for all but reproductive females (given its 'claimed' teratogenic effect with doses higher then 10 000 IU).  If you take that dose which is easily found in single capsule you would need around 2500 IU D3 which I think is more then enough - 10 000 IU D3 is overkill for majority of people and you risk some calcification. Vitamin A, D & K work synergistycally and protect toxicity of each other (K protects against calcification induced by D for example). So this is very important to do correctly. My advice - do not take AD pill supplements in normal condition - take liver oil which already contains adequate ratio and is used by millions of people for hundreds of years. Use supplemental vitamin K2 in combination. Save beta carottene when you want to go sun bathing where it has clearly demonstrated benefit of reducing sun induced skin damage - even then its probably way better to just eat carrots or pumpkins which have abnormal amounts of it. NOTE: Vitamin D Council claims that ratio should be reversed, see https://www.vitamindcouncil.org/newsletter/newsletter-vitamin-a-toxicity/. I think their arguments are weak and there is good response by Mastherjohn here: http://www.westonaprice.org/health-topics/update-on-vitamins-a-and-d/