Gender Differences in Plasma Vitamin C Concentrations and Cognitive Function: A Pilot Cross-Sectional Study in Healthy Adults

BACKGROUND: A number of investigations have highlighted the importance of vitamin C in maintaining brain health. Biologically, vitamin C has exhibited roles in neuromodulation, neurodevelopment, vascular support, and neuroprotection. Vitamin C's contribution to cognitive function in both cognitively intact and impaired cohorts has previously been assessed, with little focus on gender variability. OBJECTIVE: The present study explored the interaction between gender and plasma vitamin C on cognitive performance, and the effect of different amounts of plasma vitamin C (adequate/inadequate) on various cognitive tasks by gender. METHODS: This retrospective analysis was conducted in healthy adults (n = 80, female = 52, male = 28, 24–96 y) with a range of blood plasma vitamin C concentrations. Cognitive assessments included the Swinburne University Computerized Cognitive Assessment Battery (SUCCAB) and 2 pen-and-paper tests, the Symbol Digits Modalities Test (SDMT) and the Hopkins Verbal Learning Test–Revised (HVLT-R). Food-frequency questionnaires were used to elucidate dietary consumption. RESULTS: After adjusting for a number of potential covariates such as age, number of prescribed medications and dose of vitamin C supplementation, results indicated a significant interaction (P < 0.001) between plasma vitamin C and gender on cognitive function, on both the computerized and pen-and-paper assessments. A novel finding was that the performance of males with inadequate plasma vitamin C was poorer on tasks involving components of memory (short/delayed), inhibition, and visual perception, whereas females presenting with inadequate vitamin C were more compromised on tasks involving psychomotor performance/motor speed. Additionally, females with adequate vitamin C concentrations exhibited higher performance than males on tasks involving recall, recognition, attention, and focus. CONCLUSIONS: Further larger-scale investigations are required to establish a cause-and-effect relation and to elucidate whether differences in cognitive function between genders may be attributed to plasma vitamin C status. This trial was registered at https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=369440&isReview=true as ACTRN12615001140549.