Vitamin C is commonly associated with immune health. A new study raises a different question: Could the nutrient also be connected to how the brain ages?
Researchers found that older adults with lower levels of vitamin C in their blood plasma tended to have lower gray matter volume and lower connectivity within a group of brain regions involved in functions such as attention and autobiographical memory.
The observational study cannot show that vitamin C caused those differences or that eating more vitamin C-rich foods would protect memory or prevent dementia. The research also includes an industry connection worth noting: KAGOME CO., LTD., a food and beverage company whose products include fruit and vegetable drinks, supported salaries for two authors. Two authors are company employees and two authors own stock in the company.
Published in PLOS One, the study included 2,044 Japanese adults age 65 and older. Researchers measured vitamin C levels in participants’ blood plasma and analyzed MRI scans to examine the volume of gray matter and white matter in the brain. They also looked at connections within the default mode network, a collection of brain regions that work together and have been linked to several aspects of cognitive function.
After accounting for factors that could affect brain health, including age, physical activity habits and education level, the researchers found that participants with lower plasma vitamin C levels tended to have lower gray matter volume. They also tended to have lower connectivity within parts of the default mode network.
The study did not find a similar association involving white matter volume.
The findings add to an ongoing area of research exploring whether vitamin C status may be connected to cognitive health in older adults. Previous studies have found associations between diets higher in vitamin C and lower risks of cognitive impairment. However, the new study looked at blood levels and brain scans, not whether participants developed dementia or experienced meaningful changes in memory, attention or daily functioning.
That distinction matters. MRI scans can offer valuable clues about the aging brain, but they are not the same as clinical outcomes. The study does not show that people with higher vitamin C levels will maintain their memory longer, avoid dementia or experience a slower rate of cognitive decline.
It also does not establish an ideal vitamin C level for brain health.
Tomohiro Shintaku, one of the researchers, described the findings as a starting point for further study.
“Our study demonstrates that higher plasma vitamin C levels are associated with better preserved structural connectivity of the default mode network (DMN), a key brain network involved in cognitive function,” Shintaku said. “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.”
That hypothesis still needs to be tested. This study captured a snapshot in time. Researchers measured vitamin C levels and brain structure during the same general period, which means they cannot determine which came first. People with higher vitamin C levels may have had broader differences in their diets, health habits or overall well-being that also influenced the results.
A single plasma vitamin C measurement also has limitations. Blood levels can be affected by relatively recent dietary intake and may not fully reflect a person’s eating habits over many years. The researchers said future studies could include repeated blood tests over time and account for additional nutritional and lifestyle factors.
The study also focused on older adults in Japan. Research involving people from a broader range of racial, ethnic and socioeconomic backgrounds would help clarify whether the associations apply more widely.
Vitamin C is an essential nutrient found in many fruits and vegetables, including citrus fruits, strawberries, peppers, broccoli and tomatoes. The new findings offer another reason to value a produce-rich eating pattern. They do not provide a reason to start taking high-dose supplements or to focus too heavily on a single nutrient.
KAGOME CO., LTD., supported salaries for two authors but had no additional role in the study design, data collection, analysis, publication decision or manuscript preparation, according to the disclosure. Two authors are company employees and two authors hold stock in the company. KAGOME established a department at Hirosaki University. The study also received support from the Japan Agency for Medical Research and Development.