Saturated fatty acid intake inversely linked with stroke mortality
MedWire News: Increased dietary intake of saturated fatty acids (SFA) is associated with reduced mortality from stroke, a Japanese cohort study has found.
However, assuming the association is causal, the authors of the study say that it would be inappropriate to recommend increasing the consumption of SFA-rich products because this would also lead to an increase in blood cholesterol levels.
Hiroyasu Iso (Osaka University Graduate School of Medicine, Suita, Japan) and co-workers analyzed data from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC). The analysis included 58,453 men and women who were aged 40-79 years at baseline and were followed-up for an average of 14.1 years.
SFA intake at baseline was estimated from food-frequency questionnaires. After adjusting for energy intake, age, gender, vascular risk factors, and dietary factors, the team found that the risk for fatal stroke was inversely associated with SFA intake.
Specifically, the adjusted hazard ratio (HR) for total stroke mortality was 0.69 for the highest versus the lowest quintile of SFA intake.
More detailed analysis of different stroke subtypes revealed similar inverse associations between SFA intake and mortality from both intraparenchymal hemorrhage (HR=0.48) and ischemic stroke (HR=0.58).
By contrast, SFA intake was not associated with mortality from subarachnoid hemorrhage or heart disease (HRs=0.91 and 0.89, respectively)
Writing in the American Journal of Clinical Nutrition, Iso et al say their findings are consistent with a previous analysis of the JACC, in which increasing intake of polyunsaturated fatty acids (and hence decreasing intake of SFAs) was positively associated with stroke mortality.
"It is well known that a greater intake of SFA increases the blood total cholesterol concentration, and blood total and low-density lipoprotein cholesterol concentrations are inversely associated with risk of intraparenchymal hemorrhage," they remark.
The inverse association between SFA and ischemic stroke is more surprising, though, and is at odds with much of the published literature.
"We speculate that SFA may play different roles in intracranial large arteries as opposed to intracranial small vessels," they write.
"Low intakes of SFAs may lower blood HDL cholesterol and total and LDL cholesterol, which could partly explain the inverse association between SFA intake and stroke."
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By Joanna Lyford