Acouple of studies suggested that high doses of Vitamin A in the form of beta carotene and possibly Vitamin E lead to increased rates of lung cancer in smokers, exsmokers, and asbestos workers. The increased free radicals may potentiate the effects of smoking on the formation of cancer. Right now the general recommendation is that these people should not take more than 15mg per day of beta carotene. There are no recommendations concerning vitamin E that I'm aware of. The thinking on it is that it just didn't prevent lung cancer like the researchers had hoped.
No one currently knows how much of the vitamins added to e-
juice are even adsorbed. I think the industry should stay away from this until we can first determine the safety of inhaled vaporized nicotine alone. By adding vitamins, they are really treading in FDA's territory.