A long term prospective study has reported that eating fats—of whatever type—seems not to affect risk of ischaemic or haemorrhagic stroke in men, even though the same researchers earlier reported that omega 3 long chain fatty acids reduced the risk of ischaemic stroke. Clearly, more research is needed.

The men were healthcare professionals aged 40–75 in 1986 in the United States. Comprehensive data were obtained by validated questionnaires on their medical history, diet, and lifestyle, regularly updated over the following 14 years. When fatal or non-fatal strokes were reported a blinded physician assessed the risk factors from the medical notes. Nearly 44 000 men were studied, after exclusions for prior diagnosis of cardiovascular disease or diabetes mellitus, questionable energy intake, or incomplete data.

There were 725 cases of stroke—455 ischaemic, 125 haemorrhagic, 145 unknown—during follow up. Neither total fat nor type of fat affected risk of ischaemic or haemorrhagic stroke with data adjusted for known confounders. Long term effects, judged by comparing the highest fifth of intake with the lowest fifth in each subject, did not alter the risk for total fat or fats of different types—animal, vegetable, saturated, monounsaturated, polyunsaturated, trans unsaturated—or cholesterol. Furthermore, red meats, high fat dairy foods, nuts, and eggs had no effect.

Dietary fat intake is a big risk factor for heart disease but, apparently, not for stroke. Most of the evidence has not explored whether there might be any differences in risk between ischaemic and haemorrhagic strokes.

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