Dietary intake of fish and omega-3 fatty acids in relation to long-term dementia risk

BACKGROUND: Greater fish and omega-3 (n-3) polyunsaturated fatty acid (PUFA) intake may reduce dementia risk; however, previous studies have reported conflicting results, which were largely based on short-term follow-up. OBJECTIVE: The objective was to study the dietary consumption of fish and omega-3 PUFAs in relation to long-term dementia risk. DESIGN: We studied 5395 participants aged greater-than-or-equal55 y in the Rotterdam Study who were free of dementia and reported dietary information at baseline. We used age- and sex-adjusted Cox proportional hazard and multivariate-adjusted models to evaluate the relative risk of dementia and Alzheimer disease (AD) across categories of typical fish intake (none, low, and high) and fish type consumed (none, lean, and fatty). We also evaluated dementia and AD risk across tertiles of omega-3 PUFA intake, specifically, total long-chain omega-3 fatty acids: eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), α-linolenic acid, and EPA and DHA individually. RESULTS: During an average follow-up of 9.6 y, dementia developed in 465 participants (365 with a diagnosis of AD). In multivariate-adjusted models, total fish intake was unrelated to dementia risk (P for trend = 0.7). Compared with participants who typically ate no fish, those with a high fish intake had a similar dementia risk (hazard ratio: 0.95; 95% CI: 0.76, 1.19), as did those who typically ate fatty fish (hazard ratio: 0.98; 95% CI: 0.77, 1.24). Dietary intakes of omega-3 PUFAs were also not associated with dementia risk, and the results were similar when we considered AD specifically. CONCLUSION: In this Dutch cohort, who had a moderate consumption of fish and omega-3 PUFAs, these dietary factors do not appear to be associated with long-term dementia risk.