An orange a day keeps strokes away?

March 8, 2012

Experts believe flavonoids protect against stroke by improving blood vessel function and reducing inflammation. Is vitamin C responsible for this effect?

This prospective study examined the impact of the main dietary flavonoid subclasses on risk of stroke.

Vitamin C intake was not associated with a reduction in total or ischemic stroke risk, and adding vitamin C did not substantially change the relationship between flavanones and ischemic stroke risk.

Citrus fruits-especially oranges and grapefruit-reduce women’s risk of ischemic stroke by about 20%, according to new findings from the Nurses’ Health Study (NHS). Flavanones, a subclass of flavonoids, may be responsible for the effect.

Published online February 23 in Stroke, the first prospective study of its kind examined the impact of the main dietary flavonoid subclasses on risk of stroke. Nearly 70,000 women aged 30 and 55 participating in the NHS were included. Information on the women was collected via questionnaires over a 14-year period.

During the study period, 1,803 strokes occurred (943 ischemic, 253 hemorrhagic, and 607 of unknown type). Median total flavonoid intake in the women was 232 mg/ day. Relative risk of ischemic stroke was 0.81 (95% CI, 0.66-0.99); P=0.04) for women in the highest versus lowest quintile of flavanone intake. Oranges, orange juice, grapefruit, and grapefruit juice contain the highest amounts of flavanones.

Vitamin C intake was not associated with a reduction in total or ischemic stroke risk, and adding vitamin C did not substantially change the relationship between flavanones and ischemic stroke risk. The authors said it was not possible, in a population-based study, to determine the relative influence of all the constituents of citrus fruit.

Experts believe flavonoids protect against stroke by improving blood vessel function and reducing inflammation. More studies are needed to confirm the associations in the current research.

Read other articles in this issue of Special Delivery.