HIGHER plasma vitamin C levels are linked to better-preserved grey matter and stronger brain network connectivity in older adults, a study of more than 2,000 people suggests, hinting that the nutrient may matter for ageing brain health.
An Antioxidant with Unproven Brain Effects
Neurodegenerative disease erodes brain health in later life, and dietary vitamin C intake has been tied to lower cognitive decline risk. What stayed unclear was whether plasma vitamin C levels shape brain structure and connectivity, independent of diet.
MRI Scans Paired with Blood Measurements
The cross-sectional study analysed 2,044 participants (median age 69 years; 61.1% women), each undergoing 3T magnetic resonance imaging. Intracranial, grey matter, and white matter volumes were derived using CAT12 within SPM12, with grey- and white-to-intracranial ratios calculated to adjust for head size. Default mode network (DMN) connectivity was assessed through independent component analysis of shared grey matter variance across voxels. Multiple regression then linked plasma vitamin C levels to brain volume and DMN connectivity, adjusting for age, sex, cognitive score, diabetes, hypertension, hyperlipidaemia, education, smoking, drinking, and physical activity.
Plasma Vitamin C Tracks Grey Matter Volume
Lower plasma vitamin C levels were significantly and independently associated with a smaller grey matter to intracranial ratio (p<0.001) and weaker DMN connectivity (p<0.001). Plasma vitamin C was positively linked to both the grey matter ratio (β=0.076, SE=0.018, p<0.001) and the white matter ratio (β=0.074, SE=0.020, p<0.001). Spearman correlations confirmed positive relationships with the grey matter ratio (ρ=0.196, p<0.001) and white matter ratio (ρ=0.103, p<0.001). Among confounders, diabetes (β=-0.240, p<0.001) and smoking history (β=-0.121, p=0.027) were tied to lower grey and white matter ratios respectively. Voxel-wise analysis localised the strongest grey matter association to the posterior cingulate cortex (peak T=6.55, family-wise-error-corrected p<0.001).
A Hypothesis, Not Yet a Recommendation
The authors concluded that plasma vitamin C levels are positively associated with grey matter integrity and DMN connectivity, generating the hypothesis that the vitamin may support brain health. They highlight this as the first study linking plasma vitamin C with DMN connectivity, but stress that the cross-sectional design cannot prove cause, and that trials would be needed before any supplementation advice.
Reference
Nagaya H et al. Plasma vitamin C levels are associated with brain structural networks on MRI: a large cohort study. 2026;PLoS One.21(6):e0348504.
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