Abstract
OBJECTIVES: Dairy fat has been hypothesized to promote cardiovascular disease (CVD) due to its high saturated fat content, contributing to recommendations to consume low-fat dairy foods. However, emerging evidence indicates that dairy fat does not negatively impact CVD risk, particularly when consumed in foods with a complex matrix. Though, few trials have directly compared the effect of low-fat versus full-fat dairy foods. Therefore, we aimed to test the effects of diets rich in low-fat or full-fat dairy on CVD risk factors, compared to a limited dairy diet. We hypothesized that diets rich in dairy would not impact CVD risk factors. METHODS: Seventy-two participants with the metabolic syndrome completed a 4-week wash-in period; limiting their dairy intake to ≤ 3 servings of skim milk per week. Participants were then randomized to either continue the limited dairy diet or switch to a diet containing 3.3 servings per day of either low-fat or full-fat milk, yogurt, and cheese for 12-weeks. The plasma lipid profile and blood pressure were assessed before and after the intervention period. RESULTS: In the per protocol analysis (n = 66), there was no intervention effect on fasting plasma total-, low-density lipoprotein-, and high-density lipoprotein-cholesterol, triglycerides, free fatty acids, or cholesterol content in 38 isolated lipoprotein fractions (p > 0.1 for all variables). There was also no intervention effect on diastolic blood pressure. There was a significant difference among the diet interventions for systolic blood pressure (P = 0.045), with a trend for a decrease in the low-fat dairy diet compared to the limited dairy diet in post hoc testing after adjustment for multiple testing. CONCLUSIONS: In individuals with the metabolic syndrome, consuming 3.3 servings of dairy per day, regardless of fat content, did not affect blood lipids and modestly improved blood pressure compared to a diet virtually free of dairy. This provides further evidence that dairy fat, when consumed as part of complex whole foods, does not significantly impact CVD risk factors. FUNDING SOURCES: This work was supported by the National Dairy Council, Dairy Farmers of Canada, the Dutch Dairy Association, Dairy Australia, and the French Dairy Interbranch Organization.