High trans fat intake increased ischemic stroke risk among a large cohort of postmenopausal women, but taking aspirin appears to lessen the risk, study findings published in Annals of Neurology indicate.

Women who ate the most trans fat had a 39% greater incidence of ischemic stroke than those who ate the least amounts (hazard ratio=1.39; P =0.048 for trend), Ka He, MD, ScD, MPH, from the University of North Carolina Gillings School of Global Public Health and colleague reported.

When the researchers compared trans fat intake and ischemic stroke risk among aspirin and nonaspirin users, they found that women who took the medication and consumed high amounts of trans fat had a similar risk for stroke (P=0.43 for trend), but that this risk increased substantially among nonaspirin users. Nonaspirin users who consumed the most trans fat had a 66% increased risk for ischemic stroke compared with those who ate the least (P<0.01 for trend).

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“Our results highlight the importance of limiting the amount of dietary trans fat intake and using aspirin for primary ischemic stroke prevention among women, specifically postmenopausal women who have elevated risk of ischemic stroke,” they wrote.

Two earlier studies involving participants in the Health Professionals Follow-up Study and the Nurse’s Health Study failed to show a significant association between trans fats and ischemic stroke. But the researchers pointed out that these studies, although large, included only small numbers of stroke, thus limiting their statistical power.

In the current study, He and colleagues analyzed data from more than 1,000 incident ischemic strokes occurring among 87,025 generally healthy postmenopausal women, who participated in the Women’s Health Initiative Observational Study.

No significant associations between saturated, monounsaturated or polyunsaturated fat intake and ischemic stroke or any of it’s subtypes were observed.

Compared with the lowest trans fat intake quintile, which averaged 2.2 g per day, HRs for ischemic stroke increased with trans fat consumption (P=0.0002 for trend), even after adjusting for age and ethnicity. HRs were as follows:

  • 1.22 for the quintile that consumed an average 2.3 g per day (95% CI 0.99 to 1.51)
  • 1.37 for the quintile that got an average 2.6 g per day (95% CI 1.11 to 1.68)
  • 1.33 for the quintile that averaged 3.4 g per day (95% CI 1.09 to 1.64)
  • 1.49 for the highest intake group who averaged 6.1 g per day (95% CI 1.22 to 1.82)

“In the largest cohort study of strokes among postmenopausal women, we observed a positive association between trans fat intake and incidence of ischemic stroke that persisted after adjustment for major lifestyle, cardiovascular and dietary factors,” the researchers wrote.

Although confounding was possible, the researchers noted that it was unlikely as several sensitivity analyses repeated and validated the results.

He K et al. Ann Neurol. 2012; doi:10.1002/ana.23555.