Green tea may slash lung cancer risk

14-Jan-2010 - Last updated on 14-Jan-2010 at 11:07 GMT

Smokers who did not drink green tea at all may have a 13-fold increased risk of lung cancer, compared with those who drank at least one cup per day, suggests a new study from Taiwan.

Although expert advice is clearly to avoid tobacco smoke altogether, the results suggest smokers could benefit from upping their intake of green tea, according to findings presented at the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer.

One in three Europeans are smokers, while the US figure is one in five. Tobacco smoke contains over 4,000 compounds, of which 60 are known carcinogens. The oxidative stress levels of smokers are significantly greater than non-smokers, and as such there is a bigger drain on the levels of antioxidants in the body.

The new study, a hospital-based, randomised trial, builds on earlier research from epidemiological studies which reported potential lung cancer risk reductions in smokers.

The benefits may extend to non-smokers, researchers told attendees at the conference, with non-green tea drinkers, both smokers and non-smokers, associated with a 5.2-fold increased risk of lung cancer, compared with those who drank at least one cup of green tea per day.

I-Hsin Lin, MS, a student at Chung Shan Medical University in Taiwan told attendees that both green tea consumption and genotype may influence lung cancer risk. The study involved 170 lung cancer patients and 340 healthy patients as controls. Questionnaires revealed tea drinking habits, along with other demographic and lifestyle data. The researchers also genotyped the participants according to their insulin-like growth factors (IGF), all of which have all been reported to be associated with cancer risk.

The results showed that, in addition to an increase in risk for non-green tea drinkers, genetics seemed to affect the cancer risk. Green tea drinkers with specific types of IGF1 reported a 66 per cent reduction in lung cancer risk as compared with green tea drinkers with another form of IGF1.

"Our study may represent a clue that in the case of lung cancer, smoking-induced carcinogenesis could be modulated by green tea consumption and the growth factor environment," said Lin.

No mechanistic data was provided to explain the observations and NutraIngredients has not seen the full data.