Impact of Low-Fat and Full-Fat Dairy Intake on Cardiovascular Disease Risk Factors: A Randomized Controlled Trial

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.