North-South Differences in Dietary Structure and the Geographical Gradient of Cerebrovascular Disease: An Ecological Study Across 31 Provincial - Level Administrative Regions in China

Cerebrovascular disease is the leading cause of death and adult disability in China, and its prevalence and mortality have long displayed a pronounced north-high, south-low geographical gradient (Tu et al., 2023; Ma et al., 2021). This ecological cross-sectional study used 31 provincial-level administrative regions in mainland China as the units of analysis. It integrated 2023 per-capita consumption data for grain, meat and aquatic products from the China Statistical Yearbook 2024 with provincial age-standardised stroke prevalence reported by the national stroke screening programme. Pearson and Spearman correlations, multiple linear regression and north-south comparisons were used to examine the association between regional dietary structure and stroke prevalence. Age-standardised stroke prevalence showed a significant north-high, south-low gradient (North: 3.00% +/- 0.56%; South: 2.06% +/- 0.35%; t = 5.65, p < 0.001). In the multivariable model, per-capita grain consumption was independently and positively associated with prevalence (standardised beta = 0.52, p = 0.011), whereas per-capita meat consumption was independently and negatively associated with prevalence (beta = -0.65, p = 0.008); the model explained 30.4% of the variance. The regional salt-intake proxy was strongly and positively correlated with prevalence (r = 0.75, p < 0.001). These findings suggest that the traditional northern dietary pattern, characterised by refined grains, high salt content and relatively limited diversity in animal-source and aquatic foods, is associated with a greater stroke burden. By contrast, the more diverse southern dietary pattern, with higher aquatic-product consumption, is associated with a lower burden. Dietary optimisation, region-specific salt reduction and greater dietary diversity should therefore be considered important entry points for targeted cerebrovascular disease prevention. Given the ecological design, these associations require confirmation in individual-level studies.