Fish consumption and stroke: a community case-control study in Asturias, Spain

Abstract

Background: The relationship between fish consumption and stroke is controversial. Actually, a low fish consumption may protect against ischemic stroke, while a fish diet is ecologically associated with an increased risk of hemorrhagic stroke.

Objective: This study seeks to examine the relationship between fish consumption and stroke in a population with a high fish consumption and stroke incidence.

Methods: A population-based case-control study was performed, lasting from September 1990 to December 1991. The study comprised 440 incident cases of stroke and 473 controls between the ages of 40 and 85. Cases were defined following WHO criteria, and controls were randomly selected from the study base population. Information on fish consumption was obtained with a food frequency questionnaire.

Results: After controlling for age, energy intake and several stroke risk factors, the risk of stroke increased with the consumption of fish, chi(2) 4.12, p = 0.04. Those in the highest quintile of consumption (46 g of fish/day) had a multivariate adjusted odds ratio (OR) of 1.95 (95% CI: 1.14-3.33) as compared to those in the lowest quintile of fish consumption (11 g/ day). The risk of cerebral infarction also increased with the consumption of fish, showing an OR of 1.98 (95% CI: 1.08-3.47). Those in the highest quintile of n-3 fatty acid consumption (660 mg/day) were at borderline higher risk of stroke, with an OR of 1.76 (95% CI: 0.95-3.26), and also of cerebral infarction (OR: 1.89, 95% CI: 0.95-3.75), as compared to those in the lower quintile of n-3 fatty acids consumption (115 mg/day).

Conclusion: Although misclassification of exposure and residual confounding by unmeasured factors cannot be ruled out, a high fish consumption was associated with an increased risk of stroke and cerebral infarction in this study. More studies should be done to clarify the effect of fish consumption on stroke and stroke subtype in order to issue recommendations regarding the consumption of fish and the risk of stroke.