Wally Day wrote:

>And, what's the deal with smokers and vitamin A?
>
>
Smoking is bad for you. You are forcing the byproducts of oxidizing
(i.e. burning) plant stuff into your lungs in very concentrated form.
Oxidized material is bad for your cells. It is the primary cause of all
forms of cancer, among other things. Your body has a mechanism for
dealing with it, but this particularly nasty and concentrated form
overwhelms that system.

The whole concept of "antioxidants" is that they are substances which
get oxidized instead of the other proteins that the cell needs to
function. To use a football analogy, you could think of them as
blockers. They take the hit so that the man with the ball can keep
moving. However, when an antioxidant chemical becomes oxidized it ceases
to be helpful and becomes dangerous itself. For this reason there is a
whole system of progressively less reactive substances that pass the
buck along in a sort of chain. So, beta-carotene becomes oxidized, and
then it is restored by vitamin E which becomes oxidized, and that is
restored by Vitamin C, then by alpha-lipoic acid, etc.

In theory, what happens when you smoke is that the vitamin A, being one
of the first links in the chain, gets overwhelmed and the chain is
broken. There is too much oxidized A for the next link in the chain to
deal with, and the oxidized A causes just as much, perhaps more, damage
than the smoke would on its own.

Short answer: eat plenty of beta-carotene and DO NOT SMOKE!

see here:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15949689&itool=iconabstr&query_hl=3