The researchers, writing in The American Journal of Clinical Nutrition, found that women with the highest intake of flavonoids were half as likely to develop the disease as women who had the smallest intake.
“A flavonoid-rich diet is based on plant-based foods (such as) fruits, vegetables, whole grain cereals, nuts, legumes and their derived products (tea, chocolate, wine),” lead author Raul Zamora-Ros explained.
“This kind of diet combined with less consumption of red and processed meat can be a good way to reduce the risk of developing stomach cancer,” added Zamora-Ros, a researcher at the Catalan Institute of Oncology in Spain.
The findings do not prove that flavonoids alone can ward off the disease, because other factors such as a healthier lifestyle may play a role.
The researchers not that past research has hinted that flavonoids may help protect against cancer, but few studies have focused on stomach cancer -- the fourth most common, and the second most deadly, according to Zamora-Ros.
For the study, the researchers turned to ongoing research following almost 500,000 men and women in 10 European countries. All of the participants were between 35 and 70 years old, and had been part of the study for about 11 years.
During that time, there were 683 cases of stomach cancer, of which 288 occurred in women.
The researchers analyzed the participants’ food diaries to see how many flavonoids they are on average, then they checked to see whether or not that amount was linked to the participant’s cancer risk.
Green tea contains a large amount of flavonoids, with more than 12,511mg per 100g of leaves. Pinto beans also contain a lot, with about 769mg per 100g of beans.
Women who got more than 580mg of flavonoids per day had a 51% lower risk of developing stomach cancer than women who consumed no more than 200mg a day.
“If you look at absolute numbers, this risk reduction probably wouldn’t be as significant as if we were talking about colon cancer,” said Richard peek, director of Gastroenterology, Hepatology and Nutrition at Vanderbilt University Medical Center in Nashville, who was not involved in the study.
Zamora-Ros said a person’s exact risk depends on several factors, including whether they smoke and drink, how much red and processed meat they eat, and whether they are obese.
He added that the absence of a link between flavonoids and stomach cancer in men was a surprise, and might be due to differences in how much they smoke or drink, or to hormonal differences.
Overall, he added, the study adds more evidence that “healthy lifestyles reduce the risk of chronic diseases.”