Antioxidants prevent lung cancer after all

Smokers who get a broad spectrum of antioxidants through their diet reduce their risk of lung cancer. This is the result of the follow-up of a world famous study that for ten years has been cited in support of the opposite.

The sensational result originates from the so-called ATBC study; a Finnish study from 1994 showing that the risk of lung cancer in male smokers was not reduced but actually increased when they were given large supplements of betacarotene - the yellow pigment in carrots.

This ATBC study came as a shock to researchers all over the world; based on innumerable animal experiments until now, researchers had ben certain that antioxidants protect against cancer. The study has ever since 1994 been the most important argument for recurring warnings of antioxidants in the media.

In a new study, however, statisticians at the prestigious Yale University in America in collaboration with some Finnish colleagues have examined 1787 cases of lung cancer. This is how many of the 27,000 male heavy smokers of the ATBC study that developed lung cancer during the 14-year duration of the study. In this new study, it was not just a single antioxidant that was measured but the combined intake of the antioxidants selenium, vitamin E, vitamin C, and the coloured constituents of plants - the so-called carotenoids and flavonoids. The most comprehensive index ever seen was made in advance; it combines the total antioxidant intake in a single number.

It turned out that the 20% of smokers with the highest index had a statistically 16% reduced risk of lung cancer! In smokers who ate a lot of meat (red meat has a particularly oxidizing effect), the risk was reduced by as much as 25%! This supports the theory that it was the very antioxidizing effect that made the difference.

It is not the first time such results have been published, but they are sensational in that they originate from the actual ATBC study which has become one of the most important arguments in warning against antioxidants. In two other large studies, the risk of lung cancer was reduced by as much as 32% and 68%, respectively.

In a commentary, the researchers draw attention to the fact that the reason why the first study produced such disappointing results might have to do with the smokers not being given combinations of vitamins but only betacarotene. They therefore encourage smokers to make sure to get a broad spectrum of antioxidants as a protection against cancer.

1. Wright ME et al. Development of a comprehensive dietary antioxidant index and application to lung cancer risk in a corhort of male smokers. Am J Epidemiol 2004;160:68-76.
2. Yong LC et al.Intake og vitamins E, C and A and risk of lung cancer: The NHANES I epidemiologic follow-up study . Am J Epidemiol 1997;146:231-43.
Michaud DS et al. Intake of specific carotenoids and risk of lung cancer in 2 prospective US cohorts. Am J Clin Nutr 2000;72:990-7.