Biomarkers of dairy fatty acids and risk of cardiovascular disease in the Multi-ethnic Study of Atherosclerosis

Abstract

Background: Evidence regarding the role of dairy fat intake in cardiovascular disease (CVD) has been mixed and inconclusive. Most earlier studies have used self-reported measures of dietary intake and focused on relatively racially homogeneous populations. Circulating biomarkers of dairy fat in a multiethnic cohort provide objective measures of dairy fat intake and facilitate conclusions relevant to populations with different diets and susceptibility to CVD.

Methods and results: In a multiethnic cohort of 2837 US adults aged 45 to 84 years at baseline (2000-2002), phospholipid fatty acids including 15:0, 14:0, and trans-16:1n7 were measured using standardized methods, and the incidence of CVD prospectively adjudicated. Self-reported whole-fat dairy and butter intakes had strongest associations with 15:0, rather than 14:0 or trans-16:1n7. In multivariate models including demographics and lifestyle and dietary habits, each SD-unit of 15:0 was associated with 19% lower CVD risk (hazard ratio [95% CI] 0.81 [0.68 to 0.98]) and 26% lower coronary heart disease (CHD) risk (0.74 [0.60 to 0.92]). Associations were strengthened after mutual adjustment for 14:0 and trans-16:1n-7 and were similar after adjustment for potential mediators. Plasma phospholipid 14:0 and trans-16:1n-7 were not significantly associated with incident CVD or CHD. All findings were similar in white, black, Hispanic, and Chinese American participants.

Conclusion: Plasma phospholipid 15:0, a biomarker of dairy fat, was inversely associated with incident CVD and CHD, while no association was found with phospholipid 14:0 and trans-16:1n-7. These findings support the need for further investigation of CVD effects of dairy fat, dairy-specific fatty acids, and dairy products in general.

Keywords: cardiovascular diseases; dairy fat; diet; fatty acids.

Figure 1.

Multiadjusted differences in circulating markers of dairy according to 1 serving per day of selected food intakes in the Multi‐Ethnic Study of Atherosclerosis. Bars represent multivariate‐adjusted differences and 95% CI in plasma phospholipid fatty acid levels associated with each higher serving per day intake for selected foods, expressed as SD‐units (1 SD=0.08%, 0.05%, and 0.03% difference in 14:0, 15:0, and trans‐16:1n7 fatty acid levels, respectively). Error bars represent 95% CI. Multivariate‐adjusted models included field center, age (years), sex, race/ethnicity (non‐Hispanic whites, blacks, Hispanics, and Chinese Americans), education (<high school, high school, >high school), cigarette smoking (never, current, or former smokers and pack‐years of cigarette smoking), alcohol (g/day), physical activity (active and inactive leisure in metabolic equivalents per minute/week), body mass index (kg/m²), diabetes at baseline (no, impaired fasting glucose, yes), weekly use of dietary supplement (yes, no), energy intake (kcal/day), fiber intake (g/day), unprocessed meat (serving/day), fruits and vegetables, and mutual adjustment for all groups presented. Whole‐fat dairy included whole milk, cheese, and whole‐fat yogurt. Low‐fat dairy included 2% milk, 1%/skim milk, cottage or ricotta cheese, and low‐fat yogurt. Processed meats included ham, hot dogs, bologna, salami, lunchmeats, liver, sausage, chorizo, scrapple, and bacon. Unprocessed red included meat hamburger; cheeseburger; meatloaf; hash; beef, pork, or lamb steaks; roasts; barbeque or ribs; and red meat in stir‐fried and other mixed dishes. Salty snacks included potato, corn, or tortilla chips; crackers; pretzels; and popcorn. Desserts included white and chocolate doughnuts, cookies, cakes, brownies, candy, pastries, PopTarts, Chinese desserts, Mexican desserts, pies, pudding, custard, and flan. Fruits and vegetables included peaches, apricots, nectarines, plums, cantaloupe, mango, papaya, strawberries, blueberries, other berries, apples, applesauce, pears, bananas, plantains, oranges, grapefruit, tangerines, kiwi, dried fruits, tossed salad (with spinach, Romaine, or dark greens), cooked spinach, turnip greens, collards, broccoli, cabbage, cauliflower, Brussels sprouts, sauerkraut, kimchi, carrots, winter squash, acorn squash, sweet potatoes, yams, green beans, peas, snow peas, squash, zucchini, asparagus, and tomatoes.