Omega-6 and trans fatty acids in blood cell membranes: a risk factor for acute coronary syndromes?

Background: Although fatty acid intake has been associated with risk of coronary disease events, the association between blood omega-6 and trans fatty acids (FAs) at the time of an acute coronary syndrome (ACS) is unknown.

Methods: The relationship of blood FA composition to ACS was analyzed in 768 incident cases and 768 controls (matched on age, sex, and race).

Results: Compared to controls, ACS cases' blood cell membrane content of linoleic acid was 13% lower (P < .0001); arachidonic acid was 3.6% higher (P < .001); the trans isomer of oleic acid was 13.3% higher (P < .0001); and the trans-trans isomer of linoleic acid was 13.3% higher (P = .003). In multivariable analyses, a 1-SD decrease in linoleic acid was associated with >3 times the odds for being a case (odds ratio [OR] 3.23, 95% confidence interval [CI] 2.63-4.17). The relationship of arachidonic acid to ACS was U shaped; compared to the first quartile of arachidonic acid, the ORs for case status in the second, third, and fourth quartiles were 0.73 (95% CI 0.47-1.13), 0.65 (95% CI 0.41-1.04), and 2.32 (95% CI 1.39-3.90), respectively. The OR for a 1-SD increase in trans oleic acid was 1.24 (95% CI 1.06-1.45), and for trans-trans linoleic acid, 1.1 (95% CI 0.93-1.30). All associations were independent of membrane omega-3 FA content.

Conclusions: High blood levels of linoleic acid but low levels of trans oleic acid are inversely associated with ACS. The relationship of arachidonic acid to ACS appears more complex.