Background: Circulating linoleic acid 18:2n-6 (LA) has been considered to reflect LA intake, but its utility as a dietary biomarker could be affected by metabolism.
Objective: To study the associations of plasma and dietary LA with T2D prevalence in drug-treated patients with a history of myocardial infarction (MI).
Methods: Cross-sectional analysis of baseline data in 4,072 Dutch post-MI patients of the Alpha Omega Cohort. Circulating LA (as % of total fatty acids) was assessed in plasma cholesterol esters (CE) in the total cohort and in plasma phospholipids (PL) in a random subset of 833 patients. LA intake was assessed by a 203-item validated food frequency questionnaire. Prevalence ratios of T2D and associations with metabolic parameters were estimated in plasma and dietary LA quintiles using multivariable generalized linear models adjusted for demographic, lifestyle and dietary factors.
Results: Patients were on average 69 years old, 79% was male and 77% were overweight or obese. Most patients used statins (86%), antihypertensive drugs (90%) and antiplatelet drugs (84%). A total of 813 patients (20%) had T2D. Mean LA intake (±SD) was 5.7±2.2 energy%, and circulating LA was 49.9±5.0% in CE and 18.7±3.0% in PL. Spearman’s correlations of dietary LA with circulating LA in CE and PL were 0.16 and 0.10, respectively. Higher plasma LA, but not dietary LA, was significantly associated with a lower diabetes prevalence (Table 1). BMI (β= -0.07, p<0.001), log non-fasting triglycerides (β= -0.01, p<0.001), log non-fasting glucose (β= -0.01, p<0.001), and log alcohol intake (β= -0.03, p<0.001) were significantly associated with circulating LA in plasma CE. Similar associations were found for LA in plasma PL. Dietary LA was not significantly associated with T2D prevalence and metabolic parameters (all p>0.05).
Conclusions: Circulating LA may reflect both LA intake and metabolic state in drug-treated post-MI patients. This bears restrictions for its use as a biomarker of dietary LA intake in epidemiological studies.