Researchers have identified a compound found in oranges, grapefruits, and other citrus fruits that may lower a woman's stroke risk.
Previous studies suggest that eating fruits and vegetables helps protect against strokes, and many believe that antioxidant compounds known as flavonoids may explain why, because they have been shown to improve blood vessel function and they have anti-inflammatory effects.
Among other things, flavonoids give fruits and veggies their vibrant colors. They are also found in chocolate and red wine. By some estimates there are more than 5,000 of them.
In the newly published study, flavonoids abundant in citrus fruits known as flavanones appeared to give the most protection against stroke.
Women whose diets included the highest amount of flavanones had a 19% lower risk of suffering a blood-clot-related stroke than women with the lowest intake of the compound.
"Our study supports the conclusion that flavanones are associated with a modest reduction in stroke risk," says researcher Kathryn M. Rexrode, MD, MPH, of Boston's Harvard Medical School and Brigham and Women's Hospital.
Citrus Fruits and Stroke
Along with researchers from Norwich Medical School in the United Kingdom, Rexrode and Harvard colleagues attempted to better understand the impact of six specific subtypes of flavonoids on stroke risk.
They did this by analyzing 14 years of follow-up data on nearly 70,000 female nurses participating in a nationwide women's health study.
At enrollment and every four years thereafter, the women were asked to fill out questionnaires detailing the foods they ate.
Among the different subtypes of flavonoids, higher flavanone intake mainly from citrus fruits was specifically associated with a lower risk.
Women whose diets included the most oranges, and orange and grapefruit juices, had the lowest stroke risk.
The study appears in the April issue of the American Heart Association journal Stroke.
Public Health Message Not Simple
Rexrode says more research is needed to confirm the findings.
"I would certainly not recommend that anyone take flavanone supplements based on this research," she says.
The public health message is further complicated by the fact that grapefruit juice and fresh grapefruit can sometimes cause dangerous interactions with medications commonly prescribed to lower heart attack and stroke risk.
For example, drinking grapefruit juice can increase the risk for liver problems associated with the use of cholesterol-lowering statin drugs.
Grapefruit juice can also increase concentrations of certain blood pressure drugs, raising the risk for side effects.
Pennsylvania State University professor of nutrition and American Heart Association spokesperson Penny Kris-Etherton, PhD, says the study reinforces the public health message that eating a diet rich in a variety of fruits and vegetables protects against heart and blood vessel disease.
She recommends getting the benefits of citrus from the whole fruits instead of juices to limit sugar and calories.
"This is very provocative research which suggests that including citrus fruits in your diet could lower stroke risk," she says.