Researchers have discovered another clue that diet may influence how the brain ages. A study of more than 2,000 elderly Japanese people found that those with low levels of vitamin C in their blood tended to have less gray matter and weaker connections in important brain networks involved in memory and attention. Although the findings do not prove that vitamin C protects the brain, they strengthen the evidence that proper nutrition may play a role in maintaining subsequent cognitive function.
The study, led by Haruka Nagaya from Hirosaki University in Japan, was published in an open access journal on June 10, 2026. Pro Swan.
Vitamin C and brain structure
Previous research suggests that people who consume more vitamin C are less likely to experience cognitive impairment as they age. However, relatively few studies have examined whether vitamin C levels measured directly in the blood are associated with physical changes in the brain.
To investigate this question, researchers analyzed magnetic resonance imaging (MRI) scans and plasma samples from 2,044 Japanese adults aged 64 and older.
MRI scans were used to measure the volume of gray and white matter in each participant’s brain, accounting for differences in overall brain size. They also examined connectivity within the default mode network, a group of interconnected brain regions that play important roles in attention, autobiographical memory, and other cognitive functions.
Low vitamin C levels are associated with shrinkage of gray matter
After adjusting for factors that can also affect brain health, such as age, education level, and physical activity, the researchers found a consistent pattern. Participants with lower plasma vitamin C levels tended to have reduced gray matter volume and weaker connections within the default mode network.
The results suggest that maintaining healthy vitamin C levels may support cognitive function and healthy brain aging. However, the researchers stress that this is an observational study, meaning they cannot determine whether vitamin C directly causes these differences in brain structure and function. Further research will be required to clarify the biological mechanisms behind these statistical associations.
Future studies may strengthen the evidence by considering additional lifestyle and dietary factors, including participants from a wider range of ethnic and socio-economic backgrounds, and repeatedly measuring vitamin C levels over time.
Daily diet and brain health
Tomohiro Shintaku added, “Our study shows that higher plasma vitamin C concentrations are associated with better preserved structural connectivity of the default mode network (DMN), a major brain network involved in cognitive function. This finding raises the intriguing hypothesis that a vitamin C-rich diet may play a supporting role in maintaining brain health in older adults and mitigating age-related cognitive decline.”
He continued, “What I found most interesting about this study was that by utilizing a strong, community-based cohort of more than 2,000 older adults, we were able to detect subtle but important associations between single nutritional factors and large-scale brain networks. This study truly highlights the potential impact of our daily dietary habits on brain structure.”
Funding: Kagome Co., Ltd. Authors DK and YU provided support in the form of salary but had no additional role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are clearly explained in the Author Contributions section. Additionally, this study was supported by the Japan Agency for Medical Research and Development (AMED) under grant numbers JP16dk0207025 and JP21dk0207053.
