THURSDAY, June 5, 2008 (HealthDay News) -- Eating fruits and vegetables rich in flavonoids and drinking tea may help protect smokers from lung cancer, say researchers from the University of California, Los Angeles (UCLA).
Flavonoids are water-soluble plant pigments that have antioxidant and anti-inflammatory properties that can counteract damage to tissues. The UCLA team made the conclusion based on a study of the dietary habits of smokers with and without lung cancer.
The flavonoids that appeared to be most effective were catechin (found in strawberries and green and black teas), kaempferol (Brussels sprouts and apples) and quercetin, (beans, onions and apples).
The finding, published in the June issue of Cancer, could be important as tobacco smoking causes more than 90 percent of lung cancers.
"Since this study is the first of its type, I would usually be hesitant to make any recommendations to people about their diet," Dr. Zuo-Feng Zhang, a researcher at UCLA's Jonsson Cancer Center and a professor of public health and epidemiology, said in a prepared statement. "We really need to have several larger studies with similar results to confirm our finding. However, it's not a bad idea for everyone to eat more fruits and vegetables and drink more tea."
Flavonoids may protect against lung cancer by stopping the development of blood vessels that tumors need to grow and spread, a process called angiogenesis, Zhang said. They may also stop cancer cells from growing, allowing a naturally programmed cell death, or apoptosis, to occur.
Flavonoids' antioxidant properties may also counteract the damage tobacco smoke does to DNA, Zhang said, noting that flavonoids affect the development of lung cancer in smokers but not in nonsmokers.
"The naturally occurring chemicals may be working to reduce the damage caused by smoking," Zhang said.
He said larger studies to confirm these findings are need as well as studies to see whether flavonoids help protect against other smoking-related cancers, such as bladder, head and neck and kidney cancers.
A follow-up study into which fruits and vegetables have the most flavonoids found to be effective in first study and what an optimal number of servings per day might be to provide the best protection against lung cancer is being planned by the UCLA team.
The Linus Pauling Institute at Oregon State University has more about flavonoids.