Associations of Dairy Intake with Circulating Biomarkers of Inflammation, Insulin Response, and Dyslipidemia among Postmenopausal Women

Background: Cardiometabolic diseases are prevalent in aging Americans. Although some studies have implicated greater intake of dairy products, it is not clear how dairy intake is related to biomarkers of cardiometabolic health. Objective: Our aim was to test the hypothesis that associations of dairy foods with biomarkers of lipid metabolism, insulin-like growth factor signaling, and chronic inflammation may provide clues to understanding how dairy can influence cardiometabolic health. Design: This was a cross-sectional study in the Women's Health Initiative using baseline food frequency questionnaire data to calculate dairy intake. Participants/setting: Participants were 35,352 postmenopausal women aged 50 to 79 years at 40 clinical centers in the United States. Main outcome measures: Baseline (1993-1998) concentrations of 20 circulating biomarkers were measured. Statistical analyses: Multivariable-adjusted linear regression was used to estimate percent difference in biomarker concentrations per serving of total dairy and individual foods (milk, cheese, yogurt, butter, and low-fat varieties). Results: Lower triglyceride concentrations were associated with greater intake of total dairy (–0.8% [95% CI –1.2% to –0.3%]), mainly driven by full-fat varieties. Individual dairy foods had specific associations with circulating lipid components. For example, greater total milk intake was associated with lower concentrations of total cholesterol (–0.4% [95% CI –0.7% to –0.2%]) and high-density lipoprotein cholesterol (–0.5% [95% CI –0.9% to –0.1%]), whereas greater butter intake was associated with higher total cholesterol (0.6% [95% CI 0.2% to 1.0%]) and high-density lipoprotein cholesterol (1.6% [95% CI 1.1% to 2.0%]) concentrations. In contrast, higher total yogurt intake was associated with lower total cholesterol (–1.1% [95% CI –2.0% to –0.2%]) and higher high-density lipoprotein cholesterol (1.8% [95% CI 0.5% to 3.1%]). Greater total dairy intake (regardless of fat content), total cheese, full-fat cheese, and yogurt were consistently associated with lower concentrations of glucose, insulin, and C-reactive protein. However, milk and butter were not associated with these biomarkers. Conclusions: Higher dairy intake, except butter, was associated with a favorable profile of lipids, insulin response, and inflammatory biomarkers, regardless of fat content. Yet, specific dairy foods might influence these markers uniquely. Findings do not support a putative role of dairy in cardiometabolic diseases observed in some previous studies.