Diets rich in antioxidants such as beta-carotene and vitamins C and E may not reduce the risk of developing stroke or dementia, according to a study that counters earlier findings.
Researchers from Harvard Medical School looked at more than 5,000 people ages 55 and older who had no initial signs of dementia. At the beginning of the study, the participants completed a questionnaire about how often they ate 170 foods that were considered to have either low, moderate, or high levels of antioxidants. The participants were divided into three groups based on the amount of antioxidants they consumed and were followed for 14 years. The chance of developing stroke or dementia did not differ among any of the groups.
Comments
The main problem with the study on anti-oxidants and strokes is not the measurement error on the subjects recall of food items. The main problem is that this is a retrospective study rather than a randomized experiment. People who are prone to strokes might consume more anti-oxidants for some reason; randomization would eliminate thsi bias.