By Andrew M. Seaman
NEW YORK (Reuters Health) - Getting a moderate amount of plant substances called flavonoids through the diet may be linked to a lower stomach cancer risk in women, but not men, according to a new study.
European researchers found that women with the highest intake of flavonoids were half as likely to develop the disease as were 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)," the study's lead author Raul Zamora-Ros told Reuters Health by email.
"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.
Every year, about five out of 100,000 U.S. women get stomach cancer. The new findings don't prove that flavonoids can ward off the disease, because other factors such as a healthier lifestyle may play a role.
The researchers note that past research has hinted that flavonoids may help protect against cancer, but few studies have focused on stomach cancer - the fourth most common cancer and the second most deadly, according to Zamora-Ros.
For the new work, published in the American Journal of Clinical Nutrition, 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 stomach cancers, of which 288 occurred in women.
The researchers analyzed the participants' food diaries to see how many flavonoids they ate on average. Then they checked to see whether or not that amount was linked to the participants' cancer risk.
Green tea contains a large amount of flavonoids, with more than12,511 milligrams (mg) per 100 grams (g) of leaves. Pinto beans also contain a lot, with about 769 mg per 100 g of beans.
Women who got more than 580 mg of flavonoids per day had a 51-percent lower risk of developing stomach cancer than women who consumed no more than 200 mg 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 Dr. Richard M. Peek, director of Gastroenterology, Hepatology and Nutrition at Vanderbilt University Medical Center in Nashville. He was not involved in the new work.
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, Zamora-Ros said, the study adds more evidence that "healthy lifestyles reduce the risk of chronic diseases."
SOURCE: http://bit.ly/UDC3xx American Journal of Clinical Nutrition, online October 17, 2012.