meal may be an influential variable. Mozaffarian and collaborators investigated the association between seafood consumption and stroke risk in the Cardiovascular Health Study, an older population in whom the disease burden is high. Dietary intakes were assessed in 4775 adults aged ≥65 years (range, 65–98 years) and free of known cerebrovascular disease at baseline in 1989–1990 using a food frequency questionnaire. In a subset of this population, consumption of tuna or other broiled or baked seafood, but not fried seafood or fish sandwiches (fish burgers), correlated with plasma phospholipid long-chain omega-3 fatty acid levels. During 12 years of follow-up, participants experienced 626 incident strokes, of which 529 were ischemic strokes. Tuna/other seafood consumption was associated with a 27 percent lower risk of ischemic stroke when consumed one to four times per week (HR=0.73; 95% CI 0.55-0.98), and with a 30 percent lower risk when consumed five or more times per week (HR=0.70, 95% CI 0.50-0.99) compared with consumption of less than once per month.
Conversely, consumption of fried fish/fish sandwiches was associated with a 44 percent higher risk of ischemic stroke when consumed once per week compared with less than once per month (HR=1.44; 95% CI 1.12-1.85). Seafood consumption was not associated with hemorrhagic stroke. Consumption of tuna or other broiled or baked seafood was associated with lower risk of ischemic stroke while intake of fried seafood/fish sandwiches was associated with higher risk among elderly individuals.
Taken together, these observational studies provided inconclusive results for an association between seafood intake and stroke. These results suggest that seafood consumption may influence stroke risk; however, identification of mechanisms or alternate explanations for the results requires further study. The type of seafood meal, particularly the method of preparation, is not recorded in most observational studies but may be a major effect modifier.
The effects of seafood or EPA/DHA on serum lipid profiles have been extensively studied to determine if intake influences indicators of cardiovascular disease risk (see Appendix Table B-2c). In AHRQ Evidence Report/ Technology Assessment No. 93 (2004), Balk et al. showed that with few exceptions, serum triglyceride levels were found to decrease with increasing intake of EPA/DHA, and this change was statistically and biologically significant. Moreover, the effect appears to be dose-dependent regardless of the EPA/DHA source. Most of the studies reviewed reported net decreases of approximately 10–33 percent in triglyceride levels. Effects were dose-dependent among subjects that were healthy, had cardiovascular disease, or