The associations of serum n-6 polyunsaturated fatty acids with serum C-reactive protein in men: the Kuopio Ischaemic Heart Disease Risk Factor Study.

Background/objectives: There are concerns that high intake of n-6 polyunsaturated fatty acids (PUFA) may promote inflammation, because the end-product of n-6 PUFA metabolism, arachidonic acid, is a precursor for pro-inflammatory eicosanoids. Our aim was to investigate cross-sectional associations of the serum n-6 PUFAs, objective biomarkers for exposure, with serum high-sensitivity C-reactive protein (CRP), a key inflammation marker.

Subjects/methods: The study included 1287 generally healthy men aged 42-60 years from the population-based Kuopio Ischaemic Heart Disease Risk Factor Study, examined in 1984-1989. ANCOVA and logistic regression were used for analyses.

Results: In the multivariable-adjusted analyses, both serum total n-6 PUFA and linoleic acid, the predominant n-6 PUFA, were associated with lower CRP. The mean CRP concentrations in quartiles of linoleic acid were 1.86, 1.51, 1.53, and 1.37 mg/L (P-trend = 0.001). The odds ratio for elevated CRP (>3 mg/L) in the highest vs. the lowest quartile was 0.47 (95% confidence interval (CI) 0.25-0.87, P-trend = 0.01). Arachidonic acid or the mainly endogenously produced n-6 PUFAs, gamma-linolenic acid and dihomo-gamma-linolenic acid, were not associated with higher CRP, either. Age, body mass index, or serum long-chain n-3 PUFA concentration did not modify the associations (P-interactions > 0.14).

Conclusions: Serum n-6 PUFAs were not associated with increased inflammation in men. In contrast, the main n-6 PUFA linoleic acid had a strong inverse association with the key inflammation marker, CRP.