The purpose of this study is to find out if full-fat dairy and low-fat dairy have similar effects on risk factors for heart disease and diabetes. During the study, participants will consume two types of dairy products: low-fat dairy (milk, yogurt, and cheese) and full-fat dairy (milk, yogurt, and cheese). Each type of dairy will be consumed for 6 weeks with a ≥4-week break between. Measures will be taken to evaluate blood cholesterol, blood sugar, body weight, inflammation, blood pressure, heart health and dietary intake at the beginning and end of each 6 week period.
The overarching goal of this clinical trial is to characterize and compare the effect of full-fat dairy to low-fat dairy on low density lipoprotein cholesterol (LDL-C) and other cardiometabolic disease (CMD) risk factors in healthy adults and those at risk for CMD. This goal will be achieved with the following objectives: 1. Characterize the effect of full-fat dairy compared to low-fat dairy on LDL-C and other CMD risk factors in healthy adults and adults at risk for CMD after 6 weeks. 2. Compare the effect of full-fat dairy to low-fat dairy in healthy adults vs. adults at risk for CMD after 6 weeks. This clinical trial will test two hypotheses: 1) intake of 3 cup-equivalents/day of full-fat dairy (milk, yogurt \& cheese) has equivalent effects on LDL-C and other CMD risk factors to 3 cup-equivalents/day of low-fat dairy (milk, yogurt \& cheese) in adults with normal BMI and optimal/near optimal LDL-C, and in adults with overweight/obesity and elevated LDL-C after 6 weeks; 2) the effect of full-fat dairy on LDL-C and other CMD risk factors, compared to low-fat dairy, is equivalent in adults with normal BMI and optimal/near optimal LDL-C compared to adults with overweight/obesity and elevated LDL-C after 6 weeks. This trial is expected to demonstrate equivalent effects of full-fat and low-fat dairy on LDL-C and other CMD risk factors in both healthy and at-risk adults. This is a randomized clinical trial with 2 groups of adults. Group 1 will include adults with normal BMI (18.5 -24.9 kg/m2) and optimal/near optimal LDL-C (≤ 129 mg/dL). Group 2 will include adults with overweight/obesity (25-39.9 kg/m2) and elevated LDL-C (130-190 mg/dL). Within each group, subjects will undergo two 6-week dietary conditions in random sequence order, separated by a 4-week washout: 1) 3 cup-equivalents/day of full-fat dairy; 2) 3 cup-equivalents/day of low-fat dairy. Outcomes will be assessed at the start and end of each period.
Study Type
INTERVENTIONAL
Allocation
3 cup-equivalents/day of full-fat dairy (milk, yogurt \& cheese)
3 cup-equivalents/day of low-fat dairy (milk, yogurt \& cheese)
LDL-cholesterol change
Assessed from fasting blood draw expressed in mg/dL. LDL-cholesterol will be calculated via the Modified Sampson-NIH Equation. Change in LDL-cholesterol will be calculated as the mean of the end of intervention measures (i.e., mean of day 1 and day 2 values) minus the mean of the pre-intervention measures (i.e., mean of day 1 and day 2 values).
Time frame: 6 weeks
Apolipoprotein B change
Assessed from fasting blood draw expressed in mg/dL.
Time frame: 6 weeks
Triglycerides change
Assessed from fasting blood draw expressed in mg/dL.
Time frame: 6 weeks
Total cholesterol change
Assessed from fasting blood draw expressed in mg/dL.
Time frame: 6 weeks
HDL-cholesterol change
Assessed from fasting blood draw expressed in mg/dL.
Time frame: 6 weeks
non-HDL cholesterol change
Assessed from fasting blood draw expressed in mg/dL.
Time frame: 6 weeks
Glucose change
Assessed from fasting blood draw expressed in mg/dL.
Time frame: 6 weeks
Insulin change
Assessed from fasting blood draw expressed in micro IU/ml.
Time frame: 6 weeks
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RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
178
Fructosamine change
Assessed from fasting blood draw expressed in umol/L.
Time frame: 6 weeks
Homeostatic model of insulin resistance (HOMA-IR) change
Calculated from insulin and glucose measured from a fasting blood sample. Calculated as (insulin × glucose) / 22.5
Time frame: 6 weeks
C-reactive protein change
Assessed from fasting blood draw expressed in mg/L.
Time frame: 6 weeks
Body weight change
Measured in the fasting state using a calibrated electronic scale.
Time frame: 6 weeks
Brachial systolic and diastolic blood pressure change
Measured in the fasting state using a SphymoCor Xcel (Atcor Medical)
Time frame: 6 weeks
Central systolic and diastolic blood pressure change
Measured in the fasting state using a SphymoCor Xcel (Atcor Medical)
Time frame: 6 weeks
Carotid-femoral pulse wave velocity change
Measured in the fasting state using a SphymoCor Xcel (Atcor Medical)
Time frame: 6 weeks
Diet quality change
Healthy Eating Index-2020 assessed using 24-hour recalls
Time frame: 6 weeks