This study evaluates the subjective effects of injection administration of NR on healthy adult populations.

The purpose of this work is to explore the tolerability of Niagen®, nicotinamide riboside chloride, a specialized form of vitamin B3, via intramuscular (IM), subcutaneous (SQ), and intravenous-push (IVP) administration, in comparison to NAD+, an active comparator, administered through the same routes.

Inclusion Criteria:

• Provision of signed and dated informed consent form
• Stated willingness and demonstrated ability to comply with all study procedures, as well as availability for the duration of the study
• Lives within 100 miles of the NRI study site
• Any gender, aged 40-65, inclusive
• Good general health as evidenced by medical history
• BMI 25-34.9 kg/m2
• Sedentary behavior (defined as <20 minutes per day or 100 minutes per week of moderate to vigorous exercise)
• Demonstrated fatigue (Fatigue Assessment Scale) defined as a below-average score
• For females of reproductive potential: use of highly effective contraception for at least 1 month prior to screening and agreement to use such a method during study participation and for an additional month after the end of the study
• Agreement to adhere to Lifestyle Considerations throughout study duration

Exclusion Criteria:

• Current diagnosis of any seizure disorder, diabetes or insulin resistance, any kidney or liver disorder, heart disease, anemia, cancer, or Parkinson's disease
• ANY chronic illness (pre-disease state acceptable)
• Out of range phosphate levels at baseline
• BMI less than 25 or greater than or equal to 35
• Pregnancy, trying to conceive, or breastfeeding
• Known allergic reactions to any components of the intervention or related compounds, including any form of B3
• Positive COVID-19 test within 30 days of the study period
• Recent dramatic weight changes (10% change in body weight in the last 6 months)
• Existing usage of a NAD+ or NAD precursor supplement in any form (oral, nasal, patch, or injection/IV administration), including a B-complex supplement, within 60 days of the study, not including multivitamins.
• Introducing a new medication, supplement, investigational drug, or other intervention (including lifestyle changes) within 60 days of the start of the study.