Mediterranean diet can reduce risk of stroke by up to 25%, long-term study suggests

A Mediterranean diet can reduce the risk of every type of stroke, in some cases by as much as 25%, a large study conducted over two decades suggests.

A diet rich in olive oil, nuts, seafood, whole grains and vegetables has previously been linked to a number of health benefits. However, until now there has been limited evidence of how it might affect the risk of all forms of stroke.

The study, published in Neurology Open Access, a journal of the American Academy of Neurology, shows an association but does not prove the Mediterranean diet causes a lower risk of stroke.

However, experts not involved with the research welcomed the findings, and said there was “huge potential” to reduce a person’s chances of experiencing a stroke. Globally, more than 15 million people experience a stroke every year. Of those, 5 million die and another 5 million are left permanently disabled.

In the study led by researchers from the US and Greece, the Mediterranean diet was associated with a lower risk of stroke overall, as well as ischemic stroke and hemorrhagic stroke.

Ischemic stroke is caused when blood flow is blocked to part of the brain, and is the most common type of stroke. Hemorrhagic stroke is caused by bleeding in the brain.

“Our findings support the mounting evidence that a healthy diet is critical to stroke prevention,” said study author Sophia Wang, of City of Hope Comprehensive Cancer Centre in Duarte, California. “We were especially interested to see that this finding applies to hemorrhagic stroke, as few large studies have looked at this type of stroke.”

The study involved 105,614 women in California with an average age of 53 at the start of the study, who had no history of stroke.

Participants were given a score of zero to nine based on how closely they followed the Mediterranean diet. They received points for consuming above the overall population average in specific categories – wholegrain cereals, fruits, vegetables, legumes, olive oil and fish – and if they drank a moderate amount of alcohol.

They also received points for consuming a below-average amount of red meat and dairy products. In total, 30% of participants had scores of six to nine, the highest group, and 13% had scores of zero to two, the lowest group.

Participants were followed for an average of 21 years. After adjusting for other factors that could affect stroke risk, such as smoking, physical activity and high blood pressure, those in the highest group were 18% less likely to have a stroke than those in the lowest group.

They were also 16% less likely to have an ischemic stroke and 25% less likely to have a hemorrhagic stroke, according to the study.

“Stroke is a leading cause of death and disability, so it’s exciting to think that improving our diets could lessen our risk for this devastating disease,” said Wang. “Further studies are needed to confirm these findings and to help us understand the mechanisms behind them so we could identify new ways to prevent stroke.”

The study had limitations – it looked only at women, and participants reported their own diet data – but independent experts suggested the findings were significant.

Nine out of 10 strokes were preventable, said Juliet Bouverie, the chief executive of the Stroke Association, a charity, so there was “huge potential” to reduce the chances of a person experiencing one.

“It’s long been known that eating a Mediterranean diet can help to lower the risk of cardiovascular diseases, such as stroke,” she said. “We welcome how this has now been shown to reduce the risk of total, ischemic, and haemorrhagic strokes.

“Haemorrhagic strokes, while less frequent, are much more severe, so it’s reassuring that this study sheds light on this critical yet understudied subtype.”