Inverse association between dietary fiber intake and asymptomatic intracranial atherosclerotic stenosis in older adults: The YAHABA Study

Background: Intracranial atherosclerosis is a major cause of ischemic stroke. Asymptomatic intracranial atherosclerotic stenosis (ICAS) represents a subclinical and potentially modifiable stage preceding ischemic stroke, yet the nutritional factors associated with asymptomatic ICAS remain poorly defined. This study aimed to identify dietary factors associated with asymptomatic ICAS in community-dwelling older adults. Methods: This cross-sectional, population-based study included 962 Japanese adults aged {greater than or equal to}65 years from the Yahaba Active Aging and Healthy Brain study, conducted in Yahaba town, Japan, between July 2016 and July 2017. Asymptomatic ICAS was defined as {greater than or equal to}50% intracranial arterial stenosis evaluated by magnetic resonance angiography (MRA) without a history of stroke or transient ischemic attack. All participants underwent dietary assessment using a food frequency questionnaire. We examined the association between nutritional factors and ICAS using multivariable logistic regression models with adjustment for age, sex, hypertension, dyslipidemia, diabetes mellitus, body mass index, smoking, and alcohol use. Results: After exclusions, 850 participants were analyzed. The mean age was 73.4 {plus minus} 6.5 years, and 52% were female. ICAS was identified in 135 participants (15.9%). Participants in the highest quartile of dietary fiber intake had lower odds of ICAS than those in the lowest quartile (OR, 0.45; 95% CI, 0.26-0.80). Potassium intake showed a similar inverse association (OR, 0.49; 95% CI, 0.27-0.89). When both nutrients were included in the multivariable model as continuous variables, neither remained significant, with moderate collinearity (variance inflation factor, 4.16). Conclusions: Higher dietary fiber intake was inversely associated with asymptomatic ICAS among community-dwelling older Japanese adults. Potassium intake also showed an inverse association, although this relationship was less consistent after accounting for collinearity with dietary fiber.