The amount of research that exists on vitamin C is quite extensive, yet this vitamin’s potential benefit on cognitive function may not be the first thing that comes to mind. A study published earlier this month in Frontiers in Aging Neurosceince, brought this topic to light. Here, researchers demonstrated a significant association between plasma vitamin C levels and performance on tasks involving attention, focus, working memory, decision speed, delayed and total recall, and recognition.
This cross-sectional study included 81 healthy individuals ages 24 to 96 years of age with a range of plasma vitamin C concentrations. Cognitive assessments included The Swinburne-University-Computerized-Cognitive-Assessment-Battery (SUCCAB) and two pen and paper tests as well as the Symbol-Digits-Modalities-Test (SDMT) and Hopkins-Verbal-Learning-Test-Revised (HVLT-R). Individuals were divided into two groups: those with a plasma vitamin C level of greater than 28 μmol/L (considered adequate) and those less than 28 μmol/L (considered deficient).
The SUCCAB assessment identified a significantly higher performance ratio in the group with adequate vitamin C levels compared to those in the deficient group on reaction time, immediate recognition memory, and delayed recognition tasks. There were significantly higher scores in immediate recall on the HVLT-R, delayed recall, total recall in those with adequate plasma vitamin C concentrations. Similar results were seen on the SDMT. Hence, the researchers were able to report a significant association between vitamin C concentrations and the cognitive tasks they set out to examine.
Previous research has shown that patients with Alzheimer’s disease, who greatly need protection against oxidative damage, have considerably lower plasma levels of folate, vitamin B12, and vitamin C. (It is important to note that vitamin C and folate concentrations are much higher in the brain than in the plasma.)
Vitamin C should be assessed and supplemented accordingly and incorporated in the diet in all individuals, but especially in patients at risk for cognitive decline. Since humans cannot synthesize their own vitamin C, it is common to have insufficient levels, especially in older individuals with chronic disease. Vitamin C levels found in the tissues of the brain and muscle may be reduced to 25% of that of childhood. Serum vitamin C or oxidative stress markers that look at the functional need for water-soluble antioxidants such as 8-hydroxy-2-deoxyguanosine (8-OHdG) should be considered as part of a comprehensive assessment.
By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS