Posted by September 22nd, 2005
Beta-carotene supplements can increase the risk for tobacco-related cancers, including colorectal cancer, in smokers. However, beta-carotene has the opposite, protective effect in people who have never smoked.
In a ten-year study of 60,000 Frenchwomen, smokers with the highest intake of beta-carotene, including those who used supplements, had more than twice the risk of tobacco-related cancers and those with a low intake from fruits and vegetables. However, non-smokers with high beta-carotene intake had a lower risk of smoking related cancers: after 10 years their risk of cancer was 82 per 100,000 persons compared to 182 per 100,000 for those with a low intake.
Previous research has suggested that beta-carotene may be a co-carcinogen with tobacco smoke enhancing changes in DNA that lead to cancers.
Marie-Christine Boutron-Ruault, MD, PhD led the study which is reported in the September 21, 2005 issue of the *Journal of the National Cancer Institute*. The team concluded:
Beta-carotene intake was inversely associated with risk of tobacco-related cancers among nonsmokers with a statistically significant dose-dependent relationship, whereas high beta-carotene intake was directly associated with risk among smokers.
In an accompanying editorial, [Cigarettes: A Smoking Gun in Chemoprevention](http://jncicancerspectrum.oxfordjournals.org/cgi/content/full/jnci;97/18/1319) Susan T. Mayne and Scott M. Lippman from Yale University and M.D. Anderson Cancer Center at the University of Texas question the strength of the conclusions reached by the French study because such a small number of women actually used beta-carotene supplements. However, they stress the importance of separating smokers and non-smokers in studies of nutrients and supplementation.
[Read more about the study on *WedMD*](http://my.webmd.com/content/article/112/110328?src=RSS_PUBLIC)
[Read an article about the study on *Medicine Net*](http://www.medicinenet.com/script/main/art.asp?articlekey=53467)
[Read recommendations for use of supplements and beta-carotene rich fruits and vegetables as a result of the study on *MedPage Today*](http://www.medpagetoday.com/PrimaryCare/Smoking/tb/1777)
[Read the study abstract in the *Journal of the National Cancer Institute*](http://jncicancerspectrum.oxfordjournals.org/cgi/content/abstract/jnci;97/18/1338)