Background: Evidence on the role of dairy fat intake in cardiovascular health has been mixed and inconclusive. Most prior large studies have used self-reported measures of dietary intake and focused on relatively racially homogeneous populations. Circulating biomarkers of dairy fat in a multi-ethnic cohort provide objective measures of dairy fat intake and facilitate conclusions relevant to populations with different diets and susceptibility to CVD. Aims: To evaluate plasma phospholipid fatty acids 15:0, trans-16:1n-7 and 14:0 as objective markers of dairy fat and prospectively assess their associations with incident CVD and CHD in the Multi-Ethnic Study of Atherosclerosis (MESA). We hypothesized that circulating biomarkers of dairy fat would be inversely associated with CVD risk. Methods: We evaluated 2,837 U.S. adults 45-84 years of age at baseline (2000-2002), evenly distributed across four race-ethnic groups (Caucasians, Hispanics, African and Chinese Americans), in whom plasma phospholipid fatty acid levels were measured using validated gas-chromatography. Adjudicated CVD (MI, resuscitated cardiac arrest, definite and probable angina, stroke, and CVD death; n=189) and CHD (MI, resuscitated cardiac arrest, CHD death; n=141) were identified through 2010 during cohort examinations and follow-up calls. We also evaluated the influence of potential mediators of the associations of interest including BMI, diabetes, hypertension, HDL-C and LDL-C. Results: Self-reported intakes of whole-fat dairy and butter had the strongest association with 15:0. Self-reported dairy fat intake was more weakly associated with 14:0 and trans 16:1n7. In multivariate models including demographics, lifestyle and dietary habits (e.g. intakes of red meat, fiber, fruits, vegetables), each SD-unit of 15:0 was associated with a 19% lower CVD risk (HR and 95% CI: 0.81 [0.68,0.98]) and a 26% lower CHD risk (HR and 95% CI: 0.74 [0.60,0.92]). Associations were strengthened after mutual adjustment for 14:0 and trans16:1n-7. Results were similar after adjustment for potential mediators. Plasma phospholipid 14:0 and trans16:1n-7 were not significantly associated with incident CVD or CHD in MESA. Results were similar across the 4 race-ethnicities. Conclusion: Plasma phospholipid 15:0, a biomarker of dairy fat, was inversely associated with incident CVD and CHD. Our data support the need for further investigation of CVD effects of dairy fat, dairy-specific fatty acids, and dairy products in general.
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