Researchers have found another clue that diet may influence how the brain ages. A large new study suggests higher vitamin C levels are linked to healthier brain structure and stronger brain network connections in older adults.
In a study of more than 2,000 older adults in Japan, people with lower levels of vitamin C in their blood tended to have less gray matter and weaker connections within an important brain network involved in memory and attention.
While the findings are observational and do not prove that vitamin C protects the brain, they strengthen evidence that good nutrition could play a role in maintaining cognitive health later in life.
Vitamin C and brain structure
Earlier studies have suggested that people who consume more vitamin C are less likely to experience cognitive impairment as they get older.
However, relatively little research has examined whether vitamin C levels measured directly in the blood are associated with physical changes in the brain.
To investigate that question, the researchers analyzed magnetic resonance imaging (MRI) scans and blood plasma samples from 2,044 Japanese adults over the age of 64.
Using the MRI scans, they measured the volume of gray matter and white matter in each participant's brain while accounting for differences in overall brain size.
They also examined connectivity within the default mode network, a group of interconnected brain regions that plays an important role in attention, autobiographical memory and other cognitive functions.
Lower vitamin C linked to smaller gray matter
After adjusting for factors that can also influence brain health, including age, education level and physical activity, the researchers found a consistent pattern. Participants with lower plasma vitamin C levels tended to have reduced gray matter volume and weaker connectivity within the default mode network.
The results suggest that maintaining healthy vitamin C levels could potentially help support cognitive function and healthy brain aging.
Study limitations
However, the researchers emphasize that this was an observational study, meaning it cannot determine whether vitamin C directly causes these differences in brain structure or function.
More research will be needed to uncover the biological mechanisms behind these statistical associations.
Future studies could strengthen the evidence by measuring vitamin C levels repeatedly over time, considering additional lifestyle and dietary factors and including participants from a wider range of ethnic and socioeconomic backgrounds.
The researchers noted that 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.
How much vitamin C?
The official daily recommended intake for adults is 75 mg for females and 90 mg for males. Smokers need an additional 35 mg each day since smoking can deplete vitamin C in the body.
Some experts contend that a higher daily intake of 200 mg is needed to ensure the body’s cells and tissues are adequately supplied with vitamin C. Because some people may absorb the nutrient less efficiently, the Linus Pauling Institute recommends adults aim for 400 mg.
Vitamin C in foods
You can get 150 to 200 mg of vitamin C by eating at least 2.5 cups of fruit and vegetables each day, including ones that are rich sources of the nutrient.
Fruits high in vitamin C include strawberries (85 mg per one cup), pineapple (80 mg per one cup), citrus fruit (70 mg per one medium orange; 70 to 90 mg per one grapefruit), kiwifruit (65 mg each) and mango (60 mg per one cup).
One-half of a raw large yellow, red and green pepper each supply 171 mg, 105 mg and 65 mg of vitamin C, respectively. Other good sources include broccoli (81 mg per one cup raw), cauliflower (52 mg one cup raw), Brussels sprouts (48 mg per one half-cup cooked) and tomato juice (170 mg per one cup).
Source: PLOS One, June 10, 2026.
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