Investigation of Kava Effects on NNK Metabolism

Inclusion Criteria: * Adult ≥ 18 years * Current smoker of ≥ 5 cigarettes daily, determined by self-report * Adequate liver and kidney function, defined as: * Bilirubin, alkaline phosphatase, ALT, and AST within normal limits * Creatinine \<1.2 * Adequate hemoglobin, defined as a hemoglobin ≥12 mg/dL for men and ≥11 for women. * Ability and willingness to abstain from all medication and dietary supplements for 3 days prior to kava administration, continuing until a minimum of 7 days after kava administration. Topical medications and inhaled medications that do not contain steroids are permitted. * Ability and willingness to completely abstain from alcohol consumption for 3 days prior to kava administration, continuing until a minimum of 7 days after kava administration * Ability to understand the investigational nature of the study and provide informed consent * Willingness to take kava supplement as instructed Exclusion Criteria: * Known hepatobiliary disease or impairment * History of gastric bypass surgery, gastric banding, bowel resection, malabsorption syndromes such as celiac sprue or pancreatic insufficiency, or other conditions that may affect the absorption of kava * Chronic medication use that cannot be safely stopped * Use of tobacco products other than cigarettes (i.e. snuff, snuz, smokeless tobacco, cigars, pipes) * Major or chronic medical medical disease, including heart disease, poorly controlled diabetes, etc., to be adjudicated by the principal investigator * Women who are pregnant, intend to become pregnant within 3 months of the study period, or who are breastfeeding * Current or recent (within 12 months) problems with drug use or alcohol dependence by self-report * Antibiotic use within 2 months of study enrollment by self-report * Alcohol dependence, abuse, or history of dependence/abuse by self-report