An MRI study of 2,044 Japanese adults over age 64 found that lower blood concentrations of vitamin C were associated with reduced gray matter volume and diminished connectivity within a brain network involved in memory and higher-order thinking.
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Older adults with lower blood levels of vitamin C may be more likely to show structural changes in the brain associated with cognitive decline, according to research involving more than 2,000 participants in Japan.
Scientists at Hirosaki University analyzed blood samples and brain scans from 2,044 adults over age 64 who were enrolled in the Iki-Iki Health Promotion Project, a community-based initiative examining risk factors for dementia and cardiovascular disease. Participants had an average age of approximately 70.
Each person provided a fasting blood sample so researchers could measure plasma vitamin C concentrations. Participants then underwent MRI scans using the same high-powered imaging system, allowing the research team to compare vitamin C status with gray matter volume and structural connectivity in the brain.
The findings, published in PLOS One, showed that lower vitamin C levels were associated with less gray matter and weaker connections within the default mode network. That group of brain regions plays an important role in memory, self-reflection and other complex mental processes.
Dr. Thomas Holland, a clinician-researcher who studies cognitive aging but was not involved in the research, used a cityscape comparison to describe the results.
“Individuals with higher vitamin C levels appeared to have both more preserved ‘buildings’ and healthier ‘roadways’ connecting critical regions of the brain,” Holland told The Epoch Times.
Gray matter contains many of the brain cells involved in memory, movement, thought and information processing. Structural decline in this tissue, along with disruptions inside the default mode network, has been associated with mild cognitive impairment and Alzheimer’s disease.
Researchers adjusted their analysis for age, sex, education, cognitive status, smoking, alcohol use, diabetes, exercise and other lifestyle and health variables. The relationship between vitamin C levels and brain structure remained after those factors were considered.
“Structural loss and decreased connectivity within the DMN are known early clinical manifestations of cognitive impairment, such as in Alzheimer’s disease and mild cognitive impairment,” lead author Dr. Tomohiro Shintaku, an assistant professor at Hirosaki University, told The Epoch Times.
Shintaku said the size of the association was comparable to that seen with several recognized vascular and lifestyle risk factors.
Vitamin C may support brain health through multiple biological pathways. It functions as an antioxidant, helping neutralize free radicals that can damage cells and tissue over time. The nutrient also participates in the production of neurotransmitters, the chemical messengers that allow brain cells to communicate.
Unlike many animals, humans cannot manufacture vitamin C and must obtain it through food. Citrus fruits, berries, leafy green vegetables and several other fruits and vegetables are among the richest dietary sources.
The recommended dietary allowance is 75 milligrams per day for most adult women and 90 milligrams for most adult men. Some researchers have suggested that larger amounts may be required to fully saturate body tissues, though the intake most beneficial for long-term brain health has not been established.
Earlier studies have also linked vitamin C status with cognition. A Dutch study published in 2002 followed 5,395 people for six years and found that higher intake of vitamins C and E was associated with an 18% lower risk of Alzheimer’s disease.
A 2022 review of 12 studies found that people diagnosed with Alzheimer’s disease consistently had lower blood vitamin C levels than cognitively healthy adults. Separate research published in Neurology in 2012 reported that healthy dietary patterns and particular nutrients were associated with a nearly 40% lower risk of brain shrinkage.
Dr. Kirk Moore also identified magnesium and vitamin C as nutrients that may deserve greater attention in cognitive health during a 2025 interview.
“Magnesium and high-dose vitamin C are also crucial components often overlooked in cognitive health,” Moore said.
The Japanese study does not prove that low vitamin C directly causes brain shrinkage or disrupted neural connections. Because the research was observational, other differences between participants could have contributed to the findings.
People with higher vitamin C levels may also be more likely to eat healthier diets, exercise regularly, avoid smoking or engage in other behaviors that support brain health. Although the researchers adjusted for several of those factors, they could not eliminate every possible influence.
Older adults may be particularly vulnerable to inadequate vitamin C status. Reduced appetite, limited dietary variety and age-related changes in digestion and nutrient absorption can lower intake or availability, according to Jen Scheinman, a registered dietitian nutritionist based in New York.
Chronic illness, inflammation and certain medications may also increase the body’s need for vitamin C or affect how the nutrient is used.
Holland cautioned against viewing any single nutrient as a guaranteed defense against dementia.
“But consistently eating a nutrient-rich diet – including plenty of vitamin C-rich fruits and vegetables – may help preserve cognitive function over the long term,” Holland told The Epoch Times.
He recommended broader dietary patterns such as the Mediterranean and MIND diets, both of which emphasize vegetables, fruits, whole grains, legumes, nuts and other minimally processed foods.
Other lifestyle practices may also contribute to preserving brain volume and cognitive function. Jean Carper wrote in 100 Simple Things You Can Do to Prevent Alzheimer’s and Age-Related Memory Loss that people who meditate regularly tend to retain more gray matter and experience less age-related cognitive decline.
Gary Small likewise emphasized nutrition and daily habits as important components of brain preservation in The Alzheimer’s Prevention Program.
The new findings identify vitamin C status as a potentially modifiable factor in cognitive aging, but researchers said additional studies are needed to determine whether increasing intake can directly preserve brain tissue or slow cognitive decline.
Future research could also clarify the optimal vitamin C level for older adults and whether dietary changes, supplements or both produce measurable effects on memory, gray matter and neural connectivity.
For now, the results strengthen the broader case for diets rich in fruits and vegetables as part of a comprehensive approach to healthy brain aging.
Source: Natural News
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