Objective:

To examine the association between dietary fiber intake and dementia incidence in older adults. 

Background:

Dementia is a leading risk factor for death among older adults in the United States. Healthy dietary patterns rich in fiber have been linked to lower dementia risk. Fiber may promote brain health by improving glycemic control, regulating gut–brain communication, and reducing inflammation. Fiber intake among U.S. adults is well below recommended levels, and few studies have examined the associations of fiber intake, specifically soluble and insoluble fiber, with incident dementia.

Design/Methods:

Community-dwelling older participants (81±7 years; 75% female) from the ongoing prospective Rush Memory and Aging Project reported their usual diet at annual visits by completing a validated Food Frequency Questionnaire (FFQ) from which calorie-adjusted total, soluble, and insoluble fiber (g/day) were calculated. We selected 1,526 participants who had no history of dementia at the first FFQ and at least one complete clinical assessment after dietary data collection. Dementia was determined through annual clinical evaluations and consensus diagnosis using NINCDS/ADRDA criteria. Cox proportional hazards models of censored time to dementia with adjustment for age, sex, education, BMI, physical activity, calories, and ApoE-ε4 were used.   

Results:

During 6.9 (±4.6) years of follow-up, 430 (28.2%) participants were diagnosed with incident dementia. Higher intake of total fiber at baseline was associated with lower rates of incident dementia (Q5 vs. Q1: HR=0.66, 95%CI 0.45-0.96, p-trend=0.04). The association remained after further adjusting for vitamin E, folate, omega-3, and lutein. In a sub-sample (n=606), those in the highest quintile of insoluble fiber intake had 54% lower incidence of dementia compared to those in the lowest quintile (Q5 vs. Q1: HR=0.46, 95%CI 0.25-0.86, p-trend=0.01); however, soluble fiber had no significant associations with incident dementia. 

Conclusions:

Higher total dietary fiber intake, particularly insoluble fiber, is associated with lower rates of incident dementia.