I could not find much for Vitamin A--retinol--

But I did find some Google entries for betacarotene --Vit A precursor, for neuropathy.

I recall reading a paper a few years ago that suggested when using antioxidants like Vit E...that they should be taken in a group and not singly. Vit E alone does not help lung cancer for example. But used with betacarotene and Vit C they hand off the damaging free radicals to each other and remove them more safely.

So perhaps your doctor meant betacarotene instead of Vit A itself?