Higher levels of vitamin C were associated with healthier brain structure and stronger neural network connectivity in older adults, according to a recent study conducted in Japan.
The observational study, published in the journal PLOS ONE, included 2,044 participants in Hirosaki City, Japan, with an average age of 69. Researchers measured participants' vitamin C levels through blood samples and used MRI scans to assess gray matter and white matter volumes, as well as the structural network patterns within their brains.
Even after controlling for factors such as age, smoking, diabetes, and other lifestyle behaviors, the study found that individuals with lower vitamin C levels tended to have smaller brain tissue volumes and weaker structural network patterns. Specifically, higher vitamin C levels were linked to better-preserved gray matter and stronger connections within the default mode network (DMN), a network crucial for memory and cognitive function.
"Our study demonstrates that older adults with higher blood levels of vitamin C tend to have better-preserved brain structure (gray matter) and stronger connections within the default mode network (DMN), a crucial brain network involved in memory and cognitive function," said Tomohiro Shintaku, MD, PhD, assistant professor in the Department of Radiology Graduate School of Medicine at Hirosaki University. Shintaku noted that this is the first study to directly associate plasma vitamin C levels with the structural connectivity of the DMN.
The DMN is often impacted by conditions such as Alzheimer's disease and depression. The researchers highlighted that their method of measuring vitamin C via blood plasma was more accurate than relying solely on dietary estimates.
"What I found most fascinating is that we could detect such clear associations between a single nutritional factor (vitamin C) and large-scale brain networks in a robust cohort of over 2,000 older adults," Shintaku stated. "It highlights how significantly our everyday dietary habits might impact brain structure."
The study emphasizes the importance of obtaining vitamin C from the diet, as humans cannot produce it naturally. "Our findings suggest that maintaining optimal vitamin C levels through a healthy diet — rich in citrus fruits, berries, tomatoes and green leafy vegetables — could be a simple yet powerful way to support brain health as we age," Shintaku added.
However, the researchers acknowledged limitations, including the observational and cross-sectional nature of the study, which means it can only show association, not a cause-and-effect relationship. Reliance on a single blood measurement per participant and the potential influence of other unmeasured factors, such as body mass index and socioeconomic status, were also noted. The study's participants were primarily older Japanese adults, and the findings may not be generalizable to other populations.
Experts caution that while the study shows a signal, vitamin C status is likely one component among many that influence brain health. "That said, the study does not prove that vitamin C prevents cognitive decline or that taking supplements will improve brain health. It is best viewed as a signal that vitamin C status may be one piece of a much larger brain-health picture," commented Dung Trinh, MD, an internal medicine physician. Established risk factors like high blood pressure and blood sugar may have a more significant impact on brain health than vitamin C levels alone.