Tracing the Metabolic Flux of Orally Administered NAD+ Precursors

INCLUSION CRITERIA A participant may be enrolled if he/she is: 1. A healthy, community-living, man or a woman between 18 and 40 years, inclusive or 65 years or older 2. Has a body mass index (BMI) between 19 and 35 kg/m2, inclusive 3. Is free from clinically significant medical problems as determined by the Investigator 4. Is capable of providing written informed consent. 5. Is willing and able to provide authorization for the use and disclosure of personal health information in accordance with Health Insurance Portability and Accountability Act. EXCLUSION CRITERIA A subject may not be enrolled if s/he: 1. Has AST or ALT \> 2 times the upper limit of normal 2. Hematocrit \< 36% or \> 51% for men, or \< 35% to \> 48% for women 3. Diagnosis of diabetes, using diabetes medications or an A1C \> 6.4% 4. Serum creatinine \> 2.0 mg/dL or eGFR \<60 mL/min 5. Prohibited medications and substances: use of anabolic steroids, rhGH, DHEA, androstenedione, or any performance enhancing drug; Current use of opiates, amphetamine, cannabinoids and cocaine 6. Use of any dietary supplement. Subjects who are using a supplement containing NAM (or niacin or NMN or NR) may be included if they agree to stop supplement at least 2 weeks before randomization. 7. For women only: Pregnant or planning to get pregnant over the next 6 months, or lactating 8. Participation in an investigational trial within the past 3 months 9. Other medical conditions which, in the opinion of the investigator, would jeopardize safety or impact the validity of the study results For women only: Female of childbearing age: Use of oral contraceptives is allowed provided the contraceptive regimen was initiated at least 3 months before randomization and the participant agrees not to change the regimen during the course of the study. Excluded Medications and Treatments 1. The ingestion of the following is prohibited during 14 days prior to Day 0 and for the duration of the intervention period: * Products that contain niacin, nicotinic acid, nicotinamide in any form, other than natural foods * Herbal supplements 2. Treatment with another investigational drug, investigational device, or approved therapy for investigational use within 3 month is prohibited.