The research, on nearly 100,000 older U.S. adults, found that those getting the most flavonoids in their diets were less likely to die of heart disease or stroke over the next seven years than those who ate the least flavonoids.

The compounds are found in a range of plant foods, including many fruits (like berries, citrus and apples) and vegetables (like kale, spinach and broccoli), nuts, soy, dark chocolate, tea and wine.

Research shows that flavonoids have a number of benefits, including fighting inflammation and acting as antioxidants -- which means they help protect body cells from damage that may lead to chronic diseases and cancer.

In the current study, the researchers divided participants into five groups according to the amount of flavonoids in their diets.

The one-fifth with the highest flavonoid intake were 18 percent less likely to die of heart problems or stroke than the fifth with the lowest intake.

That difference is "modest, but still relevant," said lead researcher Marjorie L. McCullough, of the American Cancer Society in Atlanta.

Given that heart disease and stroke are so common, even a modest risk reduction can make a big difference on the population level, McCullough noted in an interview.

It's not clear that flavonoids, themselves, actually lowered people's cardiovascular risks.

But flavonoid-rich foods are the types of foods we should be eating anyway, McCullough pointed out. "This provides further support for getting more of those foods in your diet," she said.

The findings, reported in the American Journal of Clinical Nutrition, are based on more than 98,000 men and women who filled out questionnaires on diet, lifestyle and medical history. At the time, they were about 70 years old, on average.

Over the next seven years, 2,771 people died of heart disease or stroke. That included 615 deaths in the fifth with the lowest flavonoid intake at the outset, and 515 deaths in the fifth with the highest intake.

When McCullough's team accounted for other factors -- like smoking, exercise habits and weight -- people getting the most flavonoids had an 18 percent lower risk of dying from cardiovascular trouble.

Flavonoid-rich foods also contain many other healthful nutrients, McCullough said. So it's hard to know whether the compounds, themselves, deserve the credit for the lower cardiovascular risks.

For example, another recent study linked magnesium-rich foods, which include nuts and dark leafy greens that are also high in flavonoids, to lowered stroke risk. (See Reuters Health story of January 13, 2012.)

The bottom line is that getting more plant foods in your diet may make a difference in your health and longevity, according to McCullough.

And these findings suggest it may not take a huge diet change, she said.

The people with the highest flavonoid intake in the study averaged about 20 servings of fruits and 24 servings of vegetables per week. The lowest-intake group got about 11 servings of fruit and 18 servings of vegetables per week.

Lower risks were also seen among older adults whose flavonoid intake fell in between the highest and lowest groups, however.

"So even adding one serving of flavonoid-rich food a day could be beneficial," McCullough said.

In general, experts recommend getting plenty of fruits and vegetables for the good of your overall health. The "DASH" diet recommended for lowering blood pressure and protecting your heart suggests four to five servings of fruit and the same number of vegetable servings each day.

A half cup of cooked vegetables or a medium-sized piece of fresh fruit would be examples of a serving.

One caveat, McCullough said, is to be careful not to douse your flavonoid-rich foods in sugar, fat or salt. "Try to keep them close to their natural form," she said.

SOURCE: bit.ly/A9uZ9D American Journal of Clinical Nutrition, online January 4, 2012.

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