The purpose of this study is to determine nicotinamide adenine dinucleotide (NAD) levels in healthy adult subjects before and after supplementing with over-the counter nicotinamide riboside (NR) using magnetic resonance spectroscopy (MRS).

This is an open-label, nonrandomized study, primary outcome is to correlate blood and tissue measurements of NAD+ and metabolites. Investigators will recruit 12 men and 12 women aged 18-35 years and 12 men/12 women aged 70 years or older. Whole blood, serum and urine will be collected and MRS measurements performed at baseline and 30 days for in vivo determinations of nicotinamide adenine dinucleotide (NAD) and its metabolites. After baseline measurements, participants will take 1000 mcg of NR orally daily for 30 days. Baseline measurements will be repeated on days 29 and 30. Assessors of outcomes will be blinded to study status of participants.

• Male or female age18-35 years or 70 years or older, healthy
• if female reproductive potential, use of highly effective contraception (at least 1 month prior to screening and during study participation).
• No known sensitivity to NR
• No use of niacin, blood thinners or chemotherapy agents
• HbA1c below 8.5% and not diabetec requiring insulin.
• Not using/taking corticosteroids
• No laboratory abnormalities indicating significant anemia, bleeding risk, kidney disease, or liver disease
• No contraindication to MRI
• Not Pregnant, lactating, or planning to become pregnant during participation
• Not taking multivitamins or any over-the-counter supplements except calcium and vitamin D (any other supplements - discontinued 2 weeks prior to study participation).
• not taking/ undergoing another investigational drug or other intervention within the past 30 days.

related to blood, urine measurement and MRS interpretation.