Finding the right foods and nutrition supplements that help prevent cancer is a difficult aspect of research: often, when researchers think that they understand something, a newer study arrives that finds that the opposite is true.

Lung cancer was diagnosed 220,000 times last year and resulted in 160,000 fatalities. Researchers are searching for vitamins that help reduce cancer risk. Beta-carotene was once a contender as an anti-carcinogen. However in 2004, a major study found that in the case of smokers, beta-carotene supplements increased lung cancer risk.

With such reversals in their thinking, cancer researchers are careful to curb their enthusiasm over new studies that may offer hope in lung cancer prevention. However this week, there have been two new studies which have discovered very promising qualities to green tea and green vegetables.

Folic Acid and Phytochemicals

In one study which included over one thousand current or former smokers it was found that people whose diets had been high in folic acid, leafy-green vegetables and those currently taking multivitamins rich in phytochemicals (vitamins A, C, K, folate, carotenoids and lutein) showed lower levels of genetic changes causing lung cancer in smokers.

The second found that compared with Taiwanese smokers who drank at least one cup of green tea a day, smokers who did not drink green tea were almost thirteen times more likely to get lung cancer. Smokers who had genetic variations that put them at greater risk of developing lung cancer didn’t get quite as much protection from green tea as those who didn’t have those genetic variations. But they still benefited.

The polyphenols found in tea, and especially in green tea, have drawn lots of attention as potential cancer-blockers. This study was presented at a conference being held this week in Coronado, Calif., on lung cancer and its molecular origins. It’s sponsored by the American Assn. for Cancer Research.

The leafy-greens study, published in the journal Cancer Research, appeared online Tuesday. Officials of the National Cancer Institute, which funded the study, lauded the study as “well designed.” But in a statement, NCI’s biomarkers research group chief Sudhir Srivastava cautioned that more research would need to strengthen the evidence–even for leafy greens–before it could serve as the basis for dietary recommendations.

The Benefits of Leafy Greens for Lung Cancer