Dairy Macronutrient Effects on the Metabolic Syndrome

The investigators investigated changes in insulin sensitivity before and after 4 weeks of dietary intervention and control in subjects with metabolic syndrome. Two groups of subjects were studied before and after a weight maintenance diet. Group 1 was fed a common American diet with a macronutrient distribution of 10% protein, 55% carbohydrates, and 35% fat. Group 2 consumed a higher protein diet (20%; 1.4 g/kg/d of protein). Carbohydrate intake was lower in Group 2 (45%), with fat intake (largely derived from dairy sources) similar between groups. Glucose utilization and endogenous glucose production were determined during an oral glucose tolerance test (OGTT) with a novel double-tracer approach. The secondary aim was to determine the effect of a diet high in dairy consumption on blood lipid profiles. The investigators measured blood lipids before and after dietary intervention in each group.

Inclusion criteria

• Men and women, ages 45-75 years AND
• BMI greater than 30 kg/m2 AND
• Two of the following conditions:

• Plasma triglycerides > 130 mg/dl
• HDL < 40 mg/dl in men or 50 mg/dl in women
• elevated screening blood pressure (systolic > 140 or diastolic >90 mm Hg) or taking medication for hypertension
• fasting plasma glucose > 100mg/dl

Exclusion criteria

• Hemoglobin A1c > 7.5
• History of malignancy in the 6 months prior to enrollment
• History of lactose intolerance or dairy allergy
• History of gastrointestinal bypass surgery (Lapband, etc)
• History of a chronic inflammatory condition or disease (Lupus, HIV/AIDS, etc)
• Subjects who do not or will not eat animal proteins
• Subjects who cannot refrain from consuming protein or amino acid supplements during their participation in this study
• Subjects who use insulin to control their blood sugar
• Subjects whose physician will not allow suspension of oral diabetes medications for the duration of the study (~5 weeks)
• Concomitant use of corticosteroids (ingestion, injection or transdermal)
• Any other disease or condition that would place the subject at increased risk of harm if they were to participate, at the discretion of the study physician