Study links vitamin C levels to brain structure in older adults
Researchers in Japan found lower blood vitamin C levels were tied to less gray matter and weaker brain-network connections in adults over 64.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Older adults with lower blood levels of vitamin C showed signs of poorer brain structure in a large Japanese study, according to researchers reporting in PLOS One. The findings add to evidence that nutrition may be tied to brain aging, though the study does not show that vitamin C caused the differences.
The research team, led by Haruka Nagaya of Hirosaki University, analyzed data from 2,044 Japanese adults older than 64. The study was published June 10, 2026, in the open-access journal PLOS One, according to PLOS.
What the researchers measured
The investigators used MRI scans to assess brain structure and blood plasma samples to measure vitamin C levels. They examined gray matter and white matter volume while accounting for overall brain size, according to PLOS.
The team also studied connectivity in the default mode network, a set of linked brain regions involved in functions including attention and autobiographical memory. Researchers have used that network in studies of cognition and aging because changes in its connections can reflect broader brain health.
Earlier research had associated higher vitamin C intake with lower rates of cognitive impairment in older adults, according to PLOS. The new study focused on vitamin C measured directly in blood rather than estimated through diet.
Lower vitamin C tied to brain differences
After adjusting for factors including age, education and physical activity, the researchers found that people with lower plasma vitamin C levels tended to have less gray matter. They also had weaker connectivity within the default mode network, according to the study summary released by PLOS.
The findings suggest that adequate vitamin C status may be associated with healthier brain aging. But the authors described the work as observational, meaning it cannot determine whether low vitamin C contributes to brain changes, whether brain health affects diet and nutrition, or whether other factors help explain the association.
The researchers said more work is needed to identify possible biological mechanisms behind the statistical links. PLOS said future studies could improve the evidence by tracking vitamin C levels over time, accounting for more diet and lifestyle variables, and studying people from a wider range of ethnic and socioeconomic backgrounds.
Diet question remains open
Tomohiro Shintaku, one of the researchers, said the study supports the hypothesis that vitamin C-rich diets could help maintain brain health and reduce age-related cognitive decline in older adults. He also said the team was able to detect subtle associations between one nutrient and brain networks because it used a community-based cohort of more than 2,000 older adults.
The paper is titled “Plasma vitamin C levels are associated with brain structural networks on MRI: A large cohort study.” Its authors include Nagaya, Keita Watanabe, Shintaku, Miho Sasaki, Jusei Kudo, Sera Kasai, Yuka Ishimoto, Kana Saito, Shuichi Matsuhashi and others.
PLOS reported that KAGOME CO., LTD. supported the work through salaries for two authors, D.K. and Y.U., but had no additional role in study design, data collection and analysis, the publication decision or manuscript preparation. The research also received support from the Japan Agency for Medical Research and Development under grant numbers JP16dk0207025 and JP21dk0207053.
This story draws on original reporting from ScienceDaily.