[smart (OP)]

Research on beta-carotene effects on lung cancer is conflicting. Is beta-carotene a cytoprotective agent against tobacco-induced lung damage? Is it bad to take high doses of beta-carotene for a smoker ?

[evan_au]

Stopping smoking is protective against tobacco-induced lung damage.
Risks fall for about 5 years after stopping smoking, approaching the risks for non-smokers.

PS: That includes stopping marijuana...

[exothermic]

Research on beta-carotene effects on lung cancer is conflicting. Is beta-carotene a cytoprotective agent against tobacco-induced lung damage? Is it bad to take high doses of beta-carotene for a smoker ?

While the combination of smoke & beta-carotene generates oxidative byproducts such as beta-carotene epoxides, 4-nitro-beta-carotene & beta-apo-carotenals in human bronchial epithelial cell-lines, the preferential oxidation of beta-carotene does not lead to prooxidant effects [Arora et al 2001].

Also worth noting, the "conflicting effects" that you mentioned involve 2 human studies which haven't been duplicated that I know of.

Nonetheless, beta-carotene doesn't need to be supplemented as there's plenty in the diet, but to answer your question.... yes, taking large doses of any antioxidant carries the potential to shift the antioxidant- prooxidant balance toward a prooxidant status.

~

[exothermic]

PS: That includes stopping marijuana...

lol.... No need.

Any negative effects on lungs can be easily circumvented by altering administration routes.