Tracing the Metabolic Flux of Orally Administered NAD+ Precursors

We are doing this research to learn how healthy younger and older adults use two forms of vitamin B3-called nicotinamide mononucleotide (NMN) and nicotinamide (NAM)-to make NAD+. NAD+ is a natural substance that cells need for energy and other important processes. Our goal is to find out how these NAD precursors are absorbed and metabolized and how they raise NAD+ in different tissues. Who can join? Healthy adults men and women aged 18 to 40 (younger group) or 65 and older (older group) Participants with a body mass index ranging between 19 and 35 No major health issues like diabetes or severe kidney disease What will happen? Participants will take labeled or unlabeled NMN or NAM by mouth every day for 14 days. Researchers will collect blood, urine, and stool samples. Researchers also do a small muscle biopsy (under local numbing) twice to check how these NAD precursors raise NAD+ in muscle. Why is this important? NAD+ levels may drop as people age, and this drop could affect overall health and energy in cells. A better understanding of how NMN and NAM are metabolized in the body to raise NAD+ levels in both younger and older adults may help us optimize dosing and strategies for raising NAD in older people. Possible benefits and risks: Participants may not get any direct health benefit from this study; the main goal is to gather new knowledge. NMN and NAM appear safe in the doses used. A muscle biopsy may cause soreness or bruising. Researchers will monitor participants closely for any side effects throughout the study.