EPIC study finds vitamin C reduces stroke risk
A European study has found that increased blood levels of vitamin C may reduce the risk of having a stroke by 42%. The researchers established that increased levels of vitamin C offered significant cardiovascular benefits among the 20,649 men and women aged between 40 and 79 taking part in the European Prospective Investigation into Cancer (EPIC). Writing in the American Journal of Clinical Nutrition, the scientists state that blood levels of the vitamin could be used as a biological marker of lifestyle to identify people at high risk of stroke. 'An intriguing possibility is that the plasma vitamin C concentration is a good marker of a wider range of health behaviours, such as fruit and vegetable consumption, that may be protective against stroke,' they say. 'It is also plausible that vitamin C may biochemically affect stroke risk.' Strokes occur when blood clots or an artery bursts in the brain and interrupts the blood supply to a part of the brain. It is the leading cause of disability and the third leading cause of death in both Europe and the USA. According to the Stroke Alliance for Europe (SAFE), about 575,000 deaths are stroke related in Europe every year. In their study, the scientists followed 20,649 participants for 10 years and documented 448 strokes during this time. The men and women completed a health questionnaire at the start of the study, and blood samples were taken to measure vitamin C levels. The highest average blood levels of vitamin C (greater than 66 micromoles per litre) were associated with a 42% lower risk of stroke, compared to the lowest average blood levels (less than 41 micromoles per litre), after adjusting the results for potentially confounding factors such as age, sex, smoking habits, alcohol consumption, blood pressure (BP), cholesterol levels, body mass index (BMI), physical activity and the use of supplements. When the researchers excluded participants who consumed supplements containing vitamin C, the results were the same, indicating that the benefits could have been from vitamin C-rich foods, such as fruit and vegetables. According to the authors, their findings are of interest for several reasons. 'First, the strong inverse association between plasma vitamin C and stroke suggests that plasma vitamin C is likely to be a good biomarker of whatever causal factors affect stroke risk, most plausibly the dietary intake of plant foods,' they stated. 'Second, irrespective of any causal associations, plasma vitamin C appears to be a good predictive risk indicator of stroke, independent of known risk factors such as age, BP [blood pressure], smoking, lipids, diabetes, and BMI,' they added. Finally, the researchers concluded by saying: 'Given that about half of the risk of stroke is unexplained by conventional cardiovascular disease risk factors and that the predictive validity of traditional cardiovascular disease risk factors appears to diminish with age, risk markers that may help to identify those persons at greatest risk of stroke for targeted preventive interventions with established therapies, such as BP reduction, may be of interest'.