Three servings of fruits and vegetables and green or black tea daily may protect smokers from developing lung cancer, suggests a new study.
The new study from University of California, Los Angeles has found that smokers, who consume high levels of natural chemicals called flavonoids, cut their risk of developing lung cancer.
Flavonoids are water-soluble plant pigments that have antioxidant and anti-inflammatory properties, both of which can counteract damage to tissues.
"What we found was extremely interesting, that several types of flavonoids are associated with a reduced risk of lung cancer among smokers," said Dr. Zuo-Feng Zhang, a researcher at UCLA's Jonsson Cancer Center and a professor of public health and epidemiology.
"The findings were especially interesting because tobacco smoking is the major risk factor for lung cancer," Zang added.
During the study, researchers looked at 558 people with lung cancer and 837 people who did not have lung cancer and analysed their dietary history.
The findings revealed that people who ate foods containing certain flavonoids seemed to be protected from developing lung cancer.
Flavonoids protect against lung cancer by blocking the formation of blood vessels that tumours develop so they can grow and spread, a process called angiogenesis.
It also stops cancer cells from growing, allowing for naturally programmed cell death, or apoptosis, to occur.
Zhang said the flavonoids that appeared to be the most protective included catechin, found in strawberries and green and black teas, kaempferol, found in Brussels sprouts and apples, and quercetin, found in beans, onions and apples.
"Since this study is the first of its type, I would usually be hesitant to make any recommendations to people about their diet," Zhang said.
"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," Zang added.
Flavonoids' antioxidant properties may work to thwart the DNA damaging effects of tobacco smoking.
However, Zhang and his team now plans to study which types of fruits and vegetables have the highest levels of the flavonoids found to be helpful in this study.
The study was published this month in the journal Cancer.