Low vitamin C linked to weaker brain networks in older adults
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- Researchers at Hirosaki University analyzed MRI scans and blood samples from 2,044 Japanese adults over age 64, finding that lower plasma vitamin C levels correlated with reduced gray matter volume and weaker connectivity in the default mode network.
- Lead author Haruka Nagaya's study, published June 10, 2026 in PLOS One, adjusted for age, education, and physical activity but cannot prove causation because it is observational.
- Co-author Tomohiro Shintaku said detecting associations between a single nutritional factor and large-scale brain networks in a cohort this size 'highlights the potential impact of our everyday dietary habits on our brain structures.'
- The study builds on prior evidence that people who consume more vitamin C are less likely to experience cognitive impairment, by directly measuring blood levels instead of relying on dietary recall.
- KAGOME CO., LTD., the Japanese food company best known for tomato-based products, paid the salaries of two authors — a disclosed funding arrangement, though it had no role in study design or publication.
- The Japan Agency for Medical Research and Development also supported the work under grants JP16dk0207025 and JP21dk0207053.
- The researchers called for repeated vitamin C measurements over time and more diverse participant pools to confirm the findings and identify the underlying biology.
Why it matters: If a basic nutrient like vitamin C helps preserve brain network integrity, it gives clinicians a cheap, modifiable lever for counseling older patients on cognitive health — but causation remains unproven, and the Japan-specific cohort limits how broadly the result applies.
