Inclusion criteria:  Aged between 18-50 years African Americans (AAs) or European Americans (EAs) BP <140/90 mmHg Not on any prescription medications Normal kidney function (eGFR ≥ 90 ml/min/1.73 m2)  Exclusion criteria:  Pregnant or nursing Previous diagnosis of major cardiovascular diseases including myocardial infarction, congestive heart failure or stroke, diabetes, autoimmune, chronic liver and kidney disease Previous diagnosis of Crohn's disease or any other intestinal conditions Previous diagnosis of major lung diseases such as chronic obstructive pulmonary disease (COPD) Previous diagnosis of cancer Alcohol and drug abuse.