A study of 2,044 older Japanese adults found that those with lower plasma levels of vitamin C tended to have less gray matter in their brains and less connectivity between a set of brain regions known as the default mode network. Haruka Nagaya of Hirosaki University and colleagues published these findings in an open access journal. Pro Swan June 10, 2026.
Previous research has shown a link between a diet high in vitamin C and a lower risk of cognitive impairment in older adults. However, few studies have directly examined the potential association between plasma vitamin C levels and brain structure and connectivity within brain networks. To fill this gap, Nagaya and colleagues analyzed magnetic resonance imaging (MRI) scans and plasma vitamin C levels in 2,044 Japanese adults aged 64 and older.
Specifically, we measured each participant’s gray matter and white brain volumes (taking into account individual differences in total brain volume between participants). They also assessed connectivity within the default mode network, which is associated with several cognitive functions such as attention and autobiographical memory.
After statistically accounting for other factors that can influence brain structure and connectivity, such as age, physical activity habits, and education level, the researchers found that participants with lower plasma vitamin C levels also tended to have less gray matter volume and less connectivity within the default mode network.
These findings suggest that optimal levels of vitamin C in plasma may support cognitive function and counter cognitive decline. However, this finding does not support such a causal relationship between vitamin C levels and brain health, and further research is needed to explore the biological mechanisms behind the observed statistical association.
The authors also note that future studies could build on this study by considering additional lifestyle and nutritional factors, including participants of additional ethnicities and socioeconomic status, and repeating plasma vitamin C measurements over time.
Tomohiro Shintaku adds: “Our study shows that higher plasma vitamin C levels are associated with better preservation of 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 an adjunctive role in maintaining brain health and reducing age-related cognitive decline in older adults.. ”
”What I found most interesting about this study was that by utilizing a strong, community-based cohort of over 2,000 older adults, we were able to detect subtle but important associations between single nutritional factors and large-scale brain networks. This truly highlights the potential impact that our daily diet has on brain structure.. ”
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Reference magazines:
Hiroshi Nagaya Others. (2026) Plasma vitamin C levels are associated with brain structural networks on MRI: a large cohort study. PLoS One. DOI: 10.1371/journal.pone.0348504. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0348504
