Long-Term Intake of Red Meat in Relation to Dementia Risk and Cognitive Function in US Adults.

BACKGROUND AND OBJECTIVES Previous studies have shown inconsistent associations between red meat intake and cognitive health. Our objective was to examine the association between red meat intake and multiple cognitive outcomes. METHODS In this prospective cohort study, we included participants free of dementia at baseline from 2 nationwide cohort studies in the United States: the Nurses' Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS). Diets were assessed using a validated semiquantitative food frequency questionnaire. We ascertained incident dementia cases from both NHS participants (1980-2023) and HPFS participants (1986-2023). Objective cognitive function was assessed using the Telephone Interview for Cognitive Status (1995-2008) among a subset of NHS participants. Subjective cognitive decline (SCD) was self-reported by NHS participants (2012, 2014) and HPFS participants (2012, 2016). Cox proportional hazards models, general linear regression, and Poisson regression models were applied to assess the associations between red meat intake and different cognitive outcomes. RESULTS The dementia analysis included 133,771 participants (65.4% female) with a mean baseline age of 48.9 years, the objective cognitive function analysis included 17,458 female participants with a mean baseline age of 74.3 years, and SCD analysis included 43,966 participants (77.1% female) with a mean baseline age of 77.9 years. Participants with processed red meat intake ≥0.25 serving per day, compared with <0.10 serving per day, had a 13% higher risk of dementia (hazard ratio [HR] 1.13; 95% CI 1.08-1.19; plinearity < 0.001) and a 14% higher risk of SCD (relative risk [RR] 1.14; 95% CI 1.04-1.25; plinearity = 0.004). Higher processed red meat intake was associated with accelerated aging in global cognition (1.61 years per 1 serving per day increment [95% CI 0.20-3.03]) and in verbal memory (1.69 years per 1 serving per day increment [95% CI 0.13-3.25], both plinearity = 0.03). Unprocessed red meat intake of ≥1.00 serving per day, compared with <0.50 serving per day, was associated with a 16% higher risk of SCD (RR 1.16; 95% CI 1.03-1.30; plinearity = 0.04). Replacing 1 serving per day of nuts and legumes for processed red meat was associated with a 19% lower risk of dementia (HR 0.81, 95% CI 0.75-0.86), 1.37 fewer years of cognitive aging (95% CI -2.49 to -0.25), and a 21% lower risk of SCD (RR 0.79, 95% CI 0.68-0.92). DISCUSSION Higher intake of red meat, particularly processed red meat, was associated with a higher risk of developing dementia and worse cognition. Reducing red meat consumption could be included in dietary guidelines to promote cognitive health. Further research is needed to assess the generalizability of these findings to populations with diverse ethnic backgrounds.