Abstract MP006: Plasma and Erythrocyte Biomarkers of Dairy Fat Intake and Risk of Coronary Heart Disease in Men

Introduction: Intake of dairy products have been postulated to be associated with risk of coronary heart disease (CHD) because of their high saturated fat content, however studies examining this relation have yielded inconsistent results. Given the widespread consumption of dairy products, further evaluation of this controversial topic using biological markers of dairy fat intake is warranted. Objective: To evaluate plasma and erythrocyte odd chain fatty acids and certain trans isomers as biomarkers of dairy fat intake and assess their relation to risk of CHD in US men. Methods: We conducted a case-control study nested within the Health Professionals Follow-up study among 18,140 men who provided blood samples between 1993 and 1994. From baseline to 2008, four hundred and fifty-nine cases of CHD were ascertained and matched with 879 controls for age, smoking, fasting status and date of blood draw. Conditional logistic regression was used to estimate relative risks (RR) and 95% confidence intervals (95% CI) for CHD. Results: Among controls, we identified certain fatty acids that were significantly correlated with dairy fat intake: the correlation coefficients between average dairy fat intake in 1986–1994 and 15:0, 17:0, 19:0, 23:0 and trans 16:1n−7 were 0.27, 0.24, 0.10, 0.22 and 0.31 respectively for plasma and 0.25, 0.21, 0.05, 0.21 and 0.30 respectively for erythrocytes. In multivariate analyses controlling for matching factors and other diet and lifestyle risk factors, men with higher plasma concentrations of 15:0 had a significantly greater risk of CHD (RR: 1.61, 95% CI: 1.07, 2.43, p trend: 0.02, comparing extreme tertiles of plasma 15:0). Associations with other biomarkers were not significant in multivariate analyses and associations were generally weaker in erythrocytes. Conclusions: These data confirm that certain odd chain fatty acids and trans 16:1n−7 may be used as biomarkers of dairy fat intake and suggest that a high intake of dairy fat is associated with an elevated risk of CHD.