Inclusion Criteria: (Applicable to both parts)  Male/females of 40 to 65 years of age Body Mass Index (BMI) between 18.5 and 35 kg/m2 Able to provide written Informed Consent Able to follow verbal and written study directions Must not be taking or be willing to take any supplements containing any form of niacin for seven days prior to baseline and for the duration of the study. Able to maintain consistent diet and lifestyle habits throughout the study Male and female subjects must be willing to agree to use effective contraceptive methods while on treatment and for 3 months after the completion of study Willing to consume assigned supplement (NMN or placebo) for 2 months  Exclusion Criteria: (Applicable to both parts).  Participants on current use of prescription or over-the-counter nicotinic acid Use of statin drugs Having used any tobacco product or used a recreational drug in the past 6 months Having abnormal screening laboratory test values or other lab test result(s) that would preclude study participation in the judgment of the investigator Documented presence of atherosclerotic disease and/or cardiopulmonary disease History of drug or alcohol abuse History of unstable depression or mental illness within the last 6 months for which the investigator believes could impact the participant's ability to comply with study requirements Unwilling to discontinue use of conventional multivitamin/mineral or other supplements at least two weeks prior to the study start Participating in or planning to begin a weight loss diet during the study period, Lifestyle or schedule incompatible with the study protocol Known hypersensitivity to any form of niacin used during the study Women with positive result for Urine Pregnancy Test or gestation period or breastfeeding Other diseases or medications, according to the investigator, that would interfere directly in the results of the study or jeopardize the health of the participant. Currently, or within the past 30 days, enrolled in a different clinical investigation Inability to provide a venous blood sample Unable or unwilling to provide written informed consent for participation in study