Long-Term Study Revealed Low Stroke Rates Associated With Vitamin C Level In Bloodstream

Higher intake of fruits, vegetables and other foods rich in vitamin C and potassium have been associated with lower stroke rates in previous studies.

“To my knowledge, this is the first prospective study to make the correlation between vitamin C in the bloodstream and incidence of stroke,” says author Tetsuji Yokoyama, M.D., research associate in epidemiology at the Medical Research Institute of Tokyo Medical and Dental University. “The risk of stroke was inversely related to vitamin C in the bloodstream and frequency of vegetable consumption.”

The researchers examined 880 men and 1,241 women in rural Japan which were divided into four groups according to the level of vitamin C in their blood. Among the participants, 196 strokes occurred during a 20-year period beginning in 1977.

“The risk of stroke was 70 percent higher among those in the lowest quarter than those in the highest,” says Yokoyama.

When researchers examined strokes based on the number of days per week the participants ate fruits and vegetables, they found a similar relationship. The clearest association was for vegetable consumption.

“The risk of all types of stroke was 58 percent lower among those who consumed vegetables six to seven days per week, compared to those who only consumed them up to two days a week,” notes Yokoyama.

Higher concentrations of vitamin C in the blood provided benefits even in patients with other risk factors, such as high blood pressure, heavier alcohol consumption, smoking or lower physical activity. However, these risk factors did reduce the benefits somewhat. The reasons are unclear, but smoking and alcohol may interfere with vitamin C absorption or metabolism.

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