Japanese study links lower vitamin C blood levels to reduced gray matter in the brain

New research links lower vitamin C blood plasma levels in older adults to lower gray matter volume in their brains. Moreover, this was linked to lower connectivity within the default mode network — an interconnected system of brain regions that is active when the brain is at rest.

The findings suggest the possibility that optimal levels of vitamin C in blood plasma could potentially support cognitive function and counteract cognitive decline. However, as an observational study, it cannot confirm any cause-effect relationship between vitamin C levels and brain health.

Researchers at Hirosaki University, Japan, analyzed MRI scans and plasma vitamin C levels of 2,044 Japanese adults above the age of 64.

Tomohiro Shintaku, lead study author and researcher at Hirosaki University’s Department of Radiology, Graduate School of Medicine, comments: “We were able to detect these subtle but significant associations between a single nutritional factor and large-scale brain networks by utilizing a robust, community-based cohort of over 2,000 older adults. It truly highlights the potential impact of our everyday dietary habits on our brain structures.”

“Our study demonstrates that higher plasma vitamin C levels are associated with better preserved structural connectivity of the default mode network,” he adds. “This finding generates the exciting hypothesis that a diet rich in vitamin C might play a supportive role in maintaining brain health and mitigating age-related cognitive decline in older adults.”

Vitamin C and cognitive impairment

Previous studies have similarly found links between diets higher in vitamin C and lower risk of cognitive impairment in older adults, note the researchers. However, the Japanese team says there have been few that have directly looked at vitamin C levels in blood plasma and potential impacts on brain structure and connectivity within brain networks.

While previous studies link vitamin C diets to lower cognitive risk in older adults, few have directly analyzed blood plasma levels' impact on brain structure and network connectivity.The scientists measured the volume of each participant’s gray and white brain matter, while accounting for individual differences in total brain volume between the 2,044 participants, 61.1% of whom were females.

They also evaluated connectivity within the default mode network, which is associated with several cognitive functions, such as attention and autobiographical memory.

When forming their conclusion, they accounted for other factors that could affect brain structure and connectivity, including participants’ age, physical activity habits, and education level. Other major health confounders were diabetes, hypertension, or hyperlipidemia.

The authors note that future research could build on this study by taking repeated plasma vitamin C measurements over time, accounting for additional lifestyle and nutritional factors, and including participants of additional ethnicities and socioeconomic status.

In the study, published in PLOS One, the authors note that further research is needed to explore the biological mechanisms behind the observed statistical associations.

Diet and the brain

According to Innova Market Insights, brain and mood health and mental acuity are among the fastest-growing claims in dietary supplements.

Data from the market researcher further indicates that mental acuity claims grew over 22% annually (Jul 2019–Jun 2024), while brain and mood claims grew above 12% in the same period. Together, the combined claims occurred in 53% of supplement category launches in Jul 2023–Jun 2024.

Expanding beyond energy metabolism and post-workout recovery, creatine was recently spotlighted in scientific research as potentially improving brain health, according to a growing body of scientific research. Studies reveal the compound may boost cognitive function, including memory, mood, and processing speed, particularly in populations with lower baseline creatine levels, such as older adults.