New findings from Japanese researchers suggest that a common nutrient may shape the aging brain in surprising ways.

A study published in the journal PLOS ONE found that higher blood levels of vitamin C were associated with healthier brain structure among older adults.

The research involved 2,044 participants living in Hirosaki City, Japan, with an average age of 69. About 61 percent of the participants were women. All were originally part of a study examining dementia and heart disease risk.

Blood samples were collected to measure plasma vitamin C levels, and each participant underwent an MRI to assess the volume of gray and white matter in the brain.

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Tomohiro Shintaku, MD, PhD, an assistant professor in the Department of Radiology at Hirosaki University, said older adults with higher vitamin C levels tended to have better-preserved gray matter and stronger connectivity within the default mode network.

This network is crucial for processes such as memory and cognitive performance.

“While diets rich in vitamin C are known to lower the risk of cognitive decline, our study is the very first to demonstrate a direct association between actual blood plasma vitamin C levels and the structural connectivity of the DMN,” Shintaku told Fox News Digital.

Because the default mode network is often disrupted in conditions like Alzheimer’s disease and depression, the researchers highlighted the potential importance of nutrition in brain health.

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The study measured vitamin C directly in blood plasma rather than estimating dietary intake, which the scientists said made the assessment more precise.

“What I found most fascinating is that we could detect such clear associations between a single nutritional factor and large-scale brain networks in a robust cohort of over 2,000 older adults,” Shintaku said.

“It highlights how significantly our everyday dietary habits might impact brain structure.”

Researchers also pointed out that humans cannot produce their own vitamin C, reinforcing the value of obtaining it through food. They noted that a diet rich in citrus fruits, berries, tomatoes, and leafy greens could be a simple way to maintain healthy vitamin C levels.

Despite the promising patterns, the study had limitations. Shintaku emphasized that it was observational and could not prove cause and effect.

Each participant’s vitamin C level was measured only once, leaving room for variation that might influence the results.

Other lifestyle factors such as diet, body weight, and socioeconomic status could also have affected the findings. In addition, the strength of the link between vitamin C and brain structure was modest compared with other well-known risks like high blood pressure.

Dung Trinh, MD, founder of the Healthy Brain Clinic, noted to Medical News Today that the research points to a potential connection, but not a direct benefit of supplementation. “This study found an association between higher plasma vitamin C levels and MRI markers of brain health,” he said.

“That said, the study does not prove that vitamin C prevents cognitive decline or that taking supplements will improve brain health.”

Trinh and the study team agreed that vitamin C should be viewed as part of a broader picture influencing brain function. Larger studies, such as those from the UK Biobank, have shown that a range of dietary and health factors may shape brain aging outcomes.

Because almost all participants were Japanese adults, the researchers cautioned that their results may not apply to other populations.

They view the work as an early signal that nutritional status—particularly vitamin C—may be one small but meaningful piece of how the brain ages.