Antioxidant properties of beta-carotene, vitamin C and E, and trace elements may help to prevent cognitive decline, says a new French study.
The study assessed the cognitive performance of 4,447 participants aged 45–60 years (1) who were enrolled in the randomized controlled SU.VI.MAX trial: from 1994 to 2002, participants received daily doses of vitamin C (120 mg), beta-carotene (6 mg), vitamin E (30 mg), selenium (100 ?g), and zinc (20 mg) in combination or as a placebo (2). To measure potential associations between long-term antioxidant nutrient supplementation and cognitive functions, the participants performed four neuropsychological tests evaluating factors such as verbal memory and executive functioning. The study results showed that participants receiving antioxidant supplementation had better cognitive functions compared to placebo. Verbal memory was improved only for nonsmokers or subjects who had low serum vitamin C concentrations at the beginning of the study.
The researchers concluded that this study supports the role of an adequate antioxidant nutrient status in the preservation of verbal memory under certain conditions. The scientists also suggest a ceiling effect beyond which there is no additional beneficial effect of nutritional antioxidants. The participants’ preexisting good antioxidant status at the beginning of a study may explain why some randomized controlled trials (RCTs) failed to support an association between antioxidants and overall or specific cognitive functions. Middle-aged populations may be the key target populations for the evaluation of the effects of nutritional antioxidant supplementation on cognitive functions. In agreement with the study findings, an RCT carried out among men over 65 years of age provided arguments for the beneficial long-term effect of beta-carotene supplementation on the subsequent overall cognitive performance, especially for verbal memory (3). In addition, a study carried out in 65-year-old participants who received multivitamin and mineral supplements for one year only reported a beneficial effect on verbal fluency for subjects with nutritional deficiencies (4).
