Twins Nutrition Study (TwiNS): Vegan vs. Omnivore

Inclusion Criteria:

   - Age 18+

   - 1/2 of a pair of twins that will both be participating

   - Willing to consume a plant-based diet (vegetables, fruit, whole grains, legumes, etc.)

   - Willing to consume meat/eggs (beef, pork/sausage, chicken, eggs) >= 1 time a day

   - Willing to consume dairy (milk, yogurt, cheese) >= 1 time a day

Exclusion Criteria:

   - Weight < 110 lb

   - BMI >= 40

   - LDL-C > 190 mg/dL

   - Systolic Blood Pressure > 160 mmHg OR Diastolic blood pressure > 90 mmHg

   - Pregnant, lactating or planning to become pregnant during the course of the study.

   - Use of any of the following drugs/supplements within the last 2 months:

      - systemic antibiotics, antifungals, antivirals or antiparasitics (intravenous,
      intramuscular, or oral);

      - corticosteroids (intravenous, intramuscular, oral, nasal or inhaled);

      - cytokines;

      - methotrexate or immunosuppressive cytotoxic agents.

   - Chronic, clinically significant, or unstable (unresolved, requiring on-going changes
   to medical management or medication) pulmonary, cardiovascular, gastrointestinal,
   hepatic or renal functional abnormality, as determined by medical history, Type 1
   diabetes, dialysis

   - History of active cancer in the past 3 years except for squamous or basal cell
   carcinomas of the skin that have been medically managed by local excision

   - Unstable dietary history as defined by major changes in diet during the previous
   month, where the subject has eliminated or significantly increased a major food group
   in the diet.

   - Recent history of chronic excessive alcohol consumption defined as more than five
   1.5-ounce servings of 80 proof distilled spirits, five 12-ounce servings of beer or
   five 5-ounce servings of wine per day; or > 14 drinks/week.

   - Any confirmed or suspected condition/state of immunosuppression or immunodeficiency
   (primary or acquired) including HIV infection, multiple sclerosis and Graves' disease.

   - Surgery of the GI tract, with the exception of cholecystectomy and appendectomy, in
   the past five years. Any major bowel resection at any time.

   - Regular/frequent use of smoking or chewing tobacco, e-cigarettes, cigars or other
   nicotine-containing products

   - Regular use of prescription opiate pain medication