Carlos Solis
People with lower concentrations of plasma had smaller gray-matter volume and weaker neural connectivity — changes that matter for memory, attention and self-awareness.
How the study was done
The study enrolled 2,044 residents of Hirosaki, Japan, aged 64 and older. The median age was 69, and about 61% of participants were women. All joined a health-promotion project focused on dementia, stroke, heart disease and aging.
After an overnight fast, clinicians drew blood and measured plasma vitamin C, the form that circulates in the bloodstream. Every participant also had a brain MRI. The team analyzed gray-matter volume, white-matter measures and features of neural connectivity that activate during memory recall, self-reflection and mind-wandering.
After adjusting for age, sex, education, cognitive-test scores, diabetes, high blood pressure, high cholesterol, smoking, alcohol use and physical activity, the data revealed a pattern: people with lower plasma vitamin C more often showed reduced gray-matter volume and weaker neural connectivity.
In other words, low vitamin C levels correlated with brain changes that look like less well-preserved aging. That doesn’t prove a vitamin C deficiency causes brain damage, but it establishes an association worth investigating further.
Why vitamin C matters to brain researchers
Tomohiro Shintaku, a radiologist at Hirosaki University, called the findings “a hypothesis generator” and said higher plasma vitamin C was linked to better-preserved structural connectivity in networks that support cognitive function.
A vitamin C–rich diet may help maintain brain health and slow age-related cognitive decline in older adults. “May” highlights that this study was observational.
Humans cannot synthesize vitamin C, so we must get it from food: citrus, berries, tomatoes, potatoes, dark leafy greens and other sources. The brain seems to hold onto this vitamin — one human study found roughly three times higher concentrations of ascorbic acid in cerebrospinal fluid than in blood serum.
Prior work has also linked vitamin C to brain function. A 2017 systematic review found that people with better vitamin C status often performed better on cognitive tests, and people with cognitive impairment tended to have lower levels. A 2019 study associated higher vitamin C concentrations with improved attention, working memory, focus and decision speed. Later studies included analyses of hospitalized adults over 75, where vitamin C deficiency aligned with cognitive problems, and a 2025 analysis of U.S. adults that linked higher vitamin C intake with better cognitive function.
These results don’t turn vitamin C into a “brain pill.” No single nutrient explains everything. Blood pressure, blood sugar, physical activity, smoking, sleep, body weight, income and overall diet quality also influence brain health. Still, the findings reinforce a practical message: a balanced diet rich in fruits and vegetables can support brain health as part of a lifestyle that benefits the heart, blood vessels and metabolism.
Based on reporting from ZME Science
