[Dietary fat and ischemic stroke risk in Northern Portugal]

A few international studies suggest an inverse association of the intake of fat with risk of ischemic stroke. On the contrary of coronary heart disease, only 10% a 15% of ischemic strokes are associated to large vessels atherosclerosis. This suggests different mechanisms for these two pathologies. So, we design a study whose aim is to quantify the ischemic stroke risk associated to dietary fat.

A case-control study, that included two hundred ninety seven individuals of both sexes, hospitalized in the S. João Hospital in Oporto, with a first episode of ischemic stroke. Six hundred and seventy one controls of both sexes were also evaluated, selected by random digit dialing. The target population was Caucasian adults aged 44 years or older, living in the area served by the above named hospital, without cognitive abnormalities and who had not changed their dietary habits in the past year. The information was obtained by a structured questionnaire, by interview that included socio-demographic, medical and behavioural aspects (physical activity, tobacco use, food habits). Food intake in the past year was evaluated by a validated, semi-quantitative food frequency questionnaire. Logistic regression was used to evaluate the relative risk (odds ratio) and their 95% confidence intervals, with separate models fitted for men and women.

Lipids accounted for less than 30% of the total energy and less than 10% were saturated fatty acids and polyunsaturated fatty acids but the cholesterol ingestion in men were higher than 300 mg. The increasing quartiles of total lipids, monounsaturated, polyunsaturated and saturated fatty acids and cholesterol were independent protective risk factors. However, the intake of trans fatty acids increases the risk. Intake of oleic and linolenic fatty acids only had significant protection in women while intake of all n-3 fatty acids, dodecohexanoic acid in particular, had a significant protective effect in both sexes. All the n-6 fatty acids and arachidonic fatty acids also had an inverse association in women but they showed a tendency to be directly associated with ischemic stroke in men.

The total intakes of fat, saturated fat, monounsaturated fat and polyunsaturated fat were associated with reduced risk of ischemic stroke of both sexes.