Why is beta-carotene contraindicated in heavy smokers?

In 1999, the Journal of National Cancer Institute reported some findings in an animal study they had conducted on the incidence of cancer-related smoking and beta carotene intake. They used a synthetic version of beta carotene and at much higher levels than we would recommend for a daily dose. The study showed a slightly higher incidence of cancer in the group of smokers who received beta-carotene than the group of smokers without beta-carotene. Therefore it was established that giving large doses of any single synthetic antioxidant isolated can result in it becoming a pro-oxidant, so we do not supply synthetic beta carotene in high doses.

Our current recommendation for the use of natural beta-carotene is that supplemental levels (between 8-15mg per day) are reasonable and indeed safe, although labeling guidelines require us to advise with regard to smokers on the product label. Our Beta Carotene is natural and is derived from Dunaliella salina algae. It is naturally extracted from a pink alga that lives on the surface of salty lakes and contains small amounts of other mixed carotenoids. The sunflower seed oil we use is not ,