Stroke Risk Yardstick

Stroke Risk Yardstick

Your doctor may be able to assess your relative stroke risk with just two simple measures.

Measure Number 1: Vitamin C.

Top of the heap

Previous trials have shown a slight but not significant link between vitamin C supplement use and reduced stroke risk. But what about blood levels of vitamin C from dietary sources? Could evidence of a high intake of C-rich foods predict risk?

This is the question a UK team, led by University of Cambridge researchers, set out to answer in a study published last month in the American Journal of Clinical Nutrition.


  • Blood samples were taken from more than 20,600 subjects participating in the European Prospective Investigation into Cancer study
  • At baseline, subjects were between 40 and 79 years old
  • Each subject completed a questionnaire to record personal habits and conditions that impact general health
  • Researchers followed the subjects for nearly 10 years, recording 448 strokes
  • When blood levels of vitamin C were measured, subjects were divided into four groups according to their plasma vitamin C concentrations
  • Results showed that subjects in the top quartile had a 42 percent lower risk of stroke compared to subjects in the bottom quartile

The Cambridge team concluded that plasma vitamin C concentration might serve as a useful tool in identifying a patient’s stroke risk.

An editorial that accompanied the Cambridge research notes that five to nine servings of a wide variety of fruits and vegetables each day would put most people in the top vitamin C quartile.

Add just a little more

This study won’t come as a surprise to longtime e-Alert readers who have an excellent memory. In an e-Alert I sent you more than five years ago (“The Critical Second Cup” 7/1/02), I told you about a study from Finland in which researchers took blood samples from more than 2,400 middle-aged men, and then followed their health records for 10 years.

Results showed that subjects with the lowest plasma concentrations of vitamin C were almost two and a half times more likely to experience a stroke compared to subjects with the highest C levels.

One of the most interesting things about this study is that the vitamin C intake difference between subjects with high levels and subjects with low levels was not enormous. Researchers estimated that the difference between the two groups was equal to the equivalent of only about one and a half glasses of orange juice per day.

Measure for measure

And now for stroke Measure Number 2: Folate.

In the e-Alert “May Isn’t Only for Mothers” (5/15/02), the link between folate levels and stroke risk was examined by researchers at Tulane University who assessed 19 years of dietary and medical data collected from more than 9,700 subjects. When folate intake was compared to incidence of strokes and development of cardiovascular disease (CVD), researchers found that subjects who consumed at least 300 micrograms (mcg) of folate daily reduced stroke risk by 20 percent and CVD risk by 13 percent.

Dietary sources of folate (part of the B vitamin complex) include spinach, leafy green vegetables, asparagus, beans, chickpeas, and two excellent sources of vitamin C: citrus fruit and tomatoes.

“Plasma vitamin C concentrations predict risk of incident stroke over 10 y in 20,649 participants of the European Prospective Investigation into Cancer – Norfolk prospective population study” American Journal of Clinical Nutrition, Vol. 87, No. 1, January 2008,
“Dietary Intake of Folate and Risk of Stroke in US Men and Women” Stroke, Vol. 33, No. 5, May 2002,