BACKGROUND AND AIMS: N-6 polyunsaturated fatty acids (PUFA), especially linoleic acid (LA), have been inversely associated with cardiovascular disease (CVD). However, potential mechanisms underlying these associations are not completely known. We evaluated the associations of the serum concentrations of total n-6 PUFA, LA, arachidonic acid (AA), gamma-linolenic acid (GLA), and dihomo-gamma-linolenic acid (DGLA), with resting heart rate (HR), maximal HR during exercise and HR recovery after exercise. METHODS AND RESULTS: A total of 872 men free of CVD from the Kuopio Ischaemic Heart Disease Risk Factor Study, aged 42-60 years were studied. The participants performed a maximal symptom-limited exercise stress test with an electrically braked bicycle ergometer. Electrocardiogram reported continuously at rest, during the exercise test, and during recovery. Multivariable-adjusted ANCOVA was used to assess the mean values of resting HR, maximal HR and HR recovery in quartiles of serum n-6 PUFA concentrations. After multivariable adjustments, higher serum LA concentration was associated with lower resting heart rate (extreme-quartile difference = -2.61 beats/min
95%CI -4.66, -0.56
P-trend = 0.01), but not with maximal HR or HR recovery. Higher concentrations of the minor serum n-6 PUFA GLA and DGLA were only associated with higher maximal HR (for GLA extreme-quartile difference = 2.80 beats/min, 95%CI 0.08,5.52
P-trend = 0.03 and for DGLA extreme-quartile difference = 2.80 beats/min, 95%CI 0.01,5.60
P-trend = 0.03) in the fully adjusted model. AA was not associated with HR. CONCLUSION: In conclusion, higher serum LA concentration was associated with lower resting HR, while GLA and DGLA were marginally associated with higher maximal exercise HR. No associations were found with AA.