Dairy Fat and Fermentation Study

Inclusion Criteria: Age >50 years Men and postmenopausal women BMI >25 and <35 kg/m2 No milk allergy, lactose intolerance or adherence to vegan or other dietary pattern that excludes dairy products Non-smoker Usual pattern of bowel movements at least every other day. Exclusion Criteria: Women and men <50 years Women, pre- or peri-menopausal BMI <25 and >35 kg/m2 Current smokers or former smoker who quit < 6 months Use of nicotine replacement products within last 6 months Replacement or gender affirming hormonal therapy use Weight gain of >15 pounds within last 6 months Infrequent bowel movements History of anemia within past 2 years or confirmation of anemia at first study visit Blood donation within last 2 months Untreated hypertension Oral antibiotics use within 2 weeks of study entry Steroid use (including dental prophylaxis use within 2 wks prior to or during study, except non-prescription topical and nasal steroids, e. g. Flonase) Use of lipid lowering medications Chronic use of aspirin, non-steroidal anti-inflammatory medications (NSAIDS), laxatives, anti-diarrheal medication Regular use (>2 times per week) of acid lowering medication: antacids, proton pump inhibitors, or H2 Blockers. Use of dietary supplements other than multi-vitamins, including pre- and probiotics, within 2 months of study entry Milk allergy, lactose intolerance or adherence to vegan or other dietary patterns that exclude dairy products Colonoscopy within 3 weeks of study entry or during study period Diagnosis of malabsorption, inflammatory bowel disease (ulcerative colitis or Crohn's Disease), cirrhosis, history of gastrointestinal resection (other than appendectomy), chronic pancreatitis or any other chronic GI disease that in the opinion of the study physician would alter the study results Chronic heart, liver, thyroid, renal or kidney disease Type I or type II diabetes Alcohol consumption >7 drinks/week for women and >14 drinks/week for men Inadequate refrigerator storage capacity to store 21 8-oz containers of milk or yogurt Participation in other dietary intervention research study during the same time No social security number Not willing to commit to adhering to the protocol