Summary: A large neuroimaging study links circulating vitamin C levels to measures of brain structure and network function in older adults. Researchers analyzed high-resolution MRI scans together with blood plasma vitamin C measurements from 2,044 Japanese adults aged 65 and older, revealing significant associations between low plasma vitamin C, reduced gray matter volume and weakened connectivity within the brain’s default mode network (DMN).
Using objective blood biomarkers rather than dietary recall, the study provides a robust, population-based assessment of how systemic micronutrient status relates to age-related brain preservation. The authors emphasize that these are statistical associations and do not establish causality, but the results support hypotheses about antioxidant protection and encourage further longitudinal and interventional research.
Key Facts
- Objective biomarker approach: Rather than relying on self-reported diet logs, the team measured plasma vitamin C concentrations to obtain precise, objective estimates of systemic vitamin C status.
- Large, community-based cohort: The analysis included 2,044 Japanese adults (median age 69; 61.1% female), providing strong statistical power for MRI-based investigations.
- Gray matter volume association: After adjusting for differences in head size and a wide range of confounders, lower plasma vitamin C was independently associated with a smaller gray matter to intracranial volume ratio (GMV/ICV).
- DMN functional connectivity: Lower plasma vitamin C also correlated with reduced functional connectivity within the Default Mode Network, a major brain network supporting autobiographical memory, self-referential thought and background attention.
- Rigorous confounder control: Models accounted for demographic and clinical factors (age, sex, education, MMSE score, diabetes, hypertension, hyperlipidemia) and lifestyle factors (smoking, alcohol, physical activity).
- Biological interpretation: Investigators note that vitamin C’s antioxidant properties plausibly protect neurons and synapses from cumulative oxidative stress, offering a mechanistic explanation for the observed associations.
- Research implications: The authors recommend longitudinal plasma measurements and randomized trials across diverse populations to determine whether improving vitamin C status can slow or prevent brain tissue loss and connectivity decline.
Source: PLOS
Haruka Nagaya (Hirosaki University) and colleagues report these findings in PLOS One (published June 10, 2026). The investigators combined 3T MRI-derived measures of intracranial volume, gray matter volume and white matter volume with independent component analysis of resting-state data to quantify DMN connectivity. Statistical analyses used multiple regression while controlling for multiple clinical and lifestyle covariates; GMV and WMV were normalized by intracranial volume to account for individual head-size differences.
The primary results show that participants with lower plasma vitamin C had significantly lower GMV/ICV ratios and weaker DMN connectivity (both associations reporting p < 0.001). These relationships persisted after adjusting for potential confounders, indicating an independent statistical link between circulating vitamin C and both structural and functional brain measures in older adults.
The authors caution that cross-sectional data cannot prove a causal effect of vitamin C on brain health. Nonetheless, the findings align with prior epidemiological research that associates diets rich in vitamin C with reduced risk of cognitive decline, and they motivate targeted longitudinal studies and randomized controlled trials to test whether improving vitamin C status can preserve brain tissue and network integrity.
Tomohiro Shintaku, a co-author, commented that higher plasma vitamin C was associated with better-preserved DMN structure and connectivity and that this generates a testable hypothesis: that maintaining optimal vitamin C levels might support cognitive resilience in aging. The team underscores the need for repeated plasma measurements, broader demographic representation and careful control for other nutritional and lifestyle factors in future studies.
Funding: The research received support from KAGOME CO., LTD. (which provided salaries for authors D.K. and Y.U.) and by the Japan Agency for Medical Research and Development (AMED) under Grant Numbers JP16dk0207025 and JP21dk0207053. The funders had no additional role in study design, data collection, analysis, publication decisions, or manuscript preparation.
Key Questions Answered:
A: No. The study establishes a robust statistical association between plasma vitamin C and brain measures but does not demonstrate causation. Longitudinal studies and clinical trials are needed to determine whether supplementation alters the trajectory of brain aging.
A: The Default Mode Network (DMN) is a set of interconnected brain regions active during rest and internal thought. Strong DMN connectivity supports autobiographical memory, self-reflection and background attention; weakened DMN communication has been linked to cognitive decline.
A: The brain is vulnerable to oxidative stress as it ages. Vitamin C is a potent antioxidant that circulates in plasma and can protect neurons and synapses from oxidative damage, offering a plausible biological mechanism for observed associations.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The full journal paper was reviewed in detail by staff.
- Additional context was added to clarify implications and limitations.
About this neuroscience research news
Author: Hanna Abdallah
Source: PLOS
Contact: Hanna Abdallah – PLOS
Image: The image is credited to Neuroscience News
Original Research: Open access. “Plasma vitamin C levels are associated with brain structural networks on MRI: A large cohort study” by Haruka Nagaya et al., PLOS ONE. DOI:10.1371/journal.pone.0348504
Abstract
Plasma vitamin C levels are associated with brain structural networks on MRI: A large cohort study
Background
Neurodegenerative changes in older adults compromise brain structure and function. Although higher dietary vitamin C intake has been linked to lower risk of cognitive impairment, it is unclear whether plasma vitamin C independently associates with structural brain measures and network connectivity. This study examined whether plasma vitamin C levels relate to gray matter volume and DMN connectivity in older adults.
Methods
Participants underwent 3T MRI. Total intracranial volume (ICV), gray matter volume (GMV) and white matter volume (WMV) were calculated using CAT12 in SPM12. DMN connectivity was assessed by independent component analysis and quantified using loading coefficients. Multiple regression models examined associations among brain measures and plasma vitamin C, adjusting for age, sex, MMSE score, comorbidities (diabetes, hypertension, hyperlipidemia), education level, smoking, alcohol use and physical activity. GMV/ICV and WMV/ICV ratios adjusted for head size.
Results
The cross-sectional sample included 2,044 participants (median age 69; 61.1% female). Lower plasma vitamin C levels were significantly associated with reduced GMV/ICV ratio and decreased DMN connectivity (p < 0.001 for both), independent of the covariates included in the models.
Conclusions
The findings indicate that higher plasma vitamin C levels are positively associated with preserved gray matter structure and DMN connectivity in older adults. These results support the hypothesis that vitamin C may contribute to brain health, and they justify longitudinal and interventional studies to test causality and potential clinical benefits.