Feb 27, 2009 (foodconsumer.org) -- Taking certain nutrient supplements like beta-carotene and some other carotenoids-containing dietary supplements may raise the risk of lung cancer, particularly in smokers, a study published in the Feb 2009 issue of the American Journal of Epidemiology suggests.

The study led by Jessie Satia, Ph.D. at the University of North Carolina at Chapel Hill and colleagues also examined the possible effect of retinol, vitamin A, lycopene and lutein and found smokers who took supplements of these types were at higher risk of lung cancer compared to the general population.

For the study, the researchers surveyed more than 77,000 men and women aged 50 to 76 in Western Washington State for their habits of using dietary supplements over a period of 10 years and the data on the rates of lung cancer came from the Surveillance, Epidemiology and End Results cancer registry.

They found the smokers' risk of developing lung cancer increased with the length of time they took nutrient supplements like beta-carotene, retinol and lutein.   The longer they took dietary supplements, the higher the risk of lung cancer for smokers.

Specially, use of retinol and lutein supplements for a period of four years or longer was associated with increases in lung cancer risk of 53 percent and 102 percent, respectively. But the risk for nonsmokers could not be determined because there were not enough lung cancer cases among nonsmokers.

Early clinical trials have found that high doses of beta carotene seemed to raise the risk of lung cancer, Satia said. However, the risk for nonsmokers could not be determined because lung cancer cases among nonsmokers were small.

Beta-carotene and carotenoids are present in fruit and vegetables which have been linked to low incidence of cancer.   Because of the link, scientists suspected that high doses of certain nutrients may help prevent cancer.   The current study suggests that that may not necessarily be the case.

A health observer at foodconsumer.org suggests that the study merely found an association between taking dietary supplements and lung cancer risk, meaning that taking these dietary supplements may not necessarily be the cause for the increased risk of lung cancer in smokers.