The prospective study – published in Stroke – is one of the first in which researchers examine how consuming flavonoids affects the risk of stroke, with researchers finding that consumption of high amounts of certain flavonoids lower ischemic stroke risk.
The research team, from the University of East Anglia (UEA), UK, reported that women consuming the highest amounts of flavanones – a subclass of flavonoids that are found in especially high levels in citrus fruits – were associated with up to a 19% reduction in stroke risk compared to those in the group who consumed the lowest amount.
“To our knowledge, this is the first prospective study to examine the main dietary flavonoid subclasses on risk of stroke using an updated, comprehensive food database,”said the researchers, who were led by Dr Aedín Cassidy of UEA.
“Our findings suggest that bioactive compounds present in citrus may potentially be associated with a reduced risk of stroke,”added Cassidy and his team.
Cassidy and his colleagues used data from 69,622 women who took part in the 14-years of follow-up from the Nurse's Health Study. The team examined the relationship of the six main subclasses of flavonoids commonly consumed in the diet - flavanones, anthocyanins, flavan-3-ols, flavonoid polymers, flavonols and flavones - with risk of ischemic, hemorrhagic and total stroke.
The researchers did not find any beneficial association between total flavonoid consumption and stroke risk, said Cassidy, noting that this is most probably because the biological activity of the sub-classes differ.
However, the UEA team did reveal that women who ate high amounts of flavanones in citrus had a reduced risk of blood clot-related (ischemic) stroke than women who consumed the least amounts.
“Over 14 years of follow-up, high flavanone intake was associated with a 19% lower risk of ischemic stroke, a finding that fits with existing data on the protective effect of citrus fruit consumption,” said the researchers.
Cassidy and his team said further studies are needed to confirm the associations found by their research. Together with further molecular mechanistic data on flavanone this will help to inform and optimize the design of randomised trials for flavanone and citrus-based foods to potentially reduce ischemic stroke risk, they added.
Cassidy noted that flavonoids are thought to provide some of that protection through several mechanisms,“including improved blood vessel function and an anti-inflammatory effect."
"Studies have shown higher fruit, vegetable and specifically vitamin C intake is [also] associated withreduced stroke risk,"he said.
Published online ahead of print, doi: 10.1161/STROKEAHA.111.637835
“Dietary Flavonoids and Risk of Stroke in Women”
Authors: A. Cassidy, E.B. Rimm, É.J. O'Reilly, G. Logroscino,et al