The sponsor of this study is ChromaDex, Inc. This is a double-blind, randomized, crossover study to investigate the effects of 300 mg/d and 1000 mg/d TRU NIAGEN (nicotinamide riboside) compared to a placebo control on cognitive function, mood and sleep in men and women over 55 years of age. The trial is managed by Midwest Center for Metabolic and Cardiovascular Research.

Inclusion Criteria:

1. Subject is male or female, ≥55 years of age.
2. Subject has a BMI of 18.50 to 34.99 kg/m2.
3. Subject has a score of ≥80 on executive function at screening. One re-test will be allowed for subjects who require additional instruction on the CNS VS test battery.
4. Subject is willing to maintain usual diet and physical activity patterns.
5. Subject has no plans to change smoking habits during the study period.
6. Subject is willing to limit alcohol consumption to no more than one serving of alcohol per day (1 drink = 12 oz beer, 5 oz wine, or 1.5 oz hard liquor) and will abstain from consuming 2 h prior to retiring for the evening for the duration of the study.
7. Subject is willing to limit consumption of caffeine-containing beverages/foods/products to no more than 400 mg daily, with all caffeine consumption occurring prior to 6 pm.
8. Subject is willing to fast (8 - 15 h, target 10 h, water only) prior to each clinic visit.
9. Subject has no difficulties swallowing capsules.
10. Subject is willing and able to attend all clinic visits.
11. Subject understands the study procedures and signs forms documenting informed consent to participate in the study and authorization for release of relevant protected health information to the study Investigator and is willing to complete study procedures.

Exclusion Criteria:

1. Individual has history or presence of a clinically significant (in the opinion of the Investigator) psychiatric disorder or neurologic disease including epilepsy, cerebrovascular disturbance or traumatic injury.
2. Individual has a history of diagnosed clinical depression in the prior 2 years, or a score ≥20 (defined as moderate-to-severe depression) on the Beck Depression Inventory-II administered at visit 1 (week -1).
3. Individual is currently diagnosed with dementia and/or has a score <24 on the Mini Mental State Questionnaire administered at visit 1 (week -1).
4. Uncorrected abnormal vision that in the opinion of the Investigator would impair the subject's ability to complete the computerized testing (including but not limited to nearsightedness, farsightedness, and color blindness).
5. Individual has a clinically important active endocrine, cardiovascular, renal, hepatic, pulmonary, pancreatic, neurologic or biliary disorder.
6. Individual has a history of a cardiovascular event or revascularization procedure within 6 months of visit 1 (week -1).
7. Individual has a diagnosis of type I diabetes mellitus. Type 2 diabetes mellitus is excluded if the individual has experienced initiation of or a dosage change in diabetes medication(s) within 2 months of visit 1 (week -1), or has significant co-morbidities as determined by the study physician.
8. Insulin for the treatment of Type I or Type 2 diabetes mellitus is exclusionary.
9. Individual has uncontrolled hypertension (systolic blood pressure ≥160 mm Hg and/or diastolic blood pressure ≥100 mm Hg).
10. Individual has a recent history (prior 5 years) or the presence of cancer other than non-melanoma skin cancer.
11. Individual has a history or presence of a chronic pain condition requiring regular use of opioid therapy.
12. Individual has a recent history or strong potential for drug or alcohol abuse defined as >14 drinks per week (1 drink = 12 oz beer, 5 oz wine, or 1 ½ oz distilled spirits).
13. Individual has a history of unconventional sleep patterns (e.g., night shift) or chronic insomnia (at least 3 d/week over the past month), a diagnosed sleep disorder, or a chronic medical condition with the potential to impact energy/fatigue levels.
14. Individuals taking any form of niacin >25 mg/d and any use of nicotinamide riboside within 2 weeks of visit 1 (week -1).
15. Individual is a heavy consumer of caffeinated beverages (>400 mg/d within 2 weeks of visit 1).
16. Individual has a history of using psychotropic medications (including antidepressants and tranquilizers), stimulant medications, and/or narcotics within 4 weeks of visit 1 (week -1).
17. Individual has used sleep aid medications, supplements, and/or products, including antihistamines, within 2 weeks of visit 1 (week -1) A washout prior to screening is allowed).
18. Individual has a known allergy to any ingredients in the study products.
19. Individual is pregnant, planning to be pregnant during the study period, lactating, or is of childbearing potential and is unwilling to commit to use of a medically approved form of contraception throughout the study period.
20. Subject has an active infection or has used antibiotics within 5 d of any clinic visit. For those with an active infection and/or using antibiotics, subjects must wait at least 5 d after the infection resolves or antibiotic use is complete. The test period will be extended for completion in these cases.
21. Subject has been exposed to any non-registered drug product within 30 d of visit 1 (week -1).
22. Individual has a condition the Investigator believes would interfere with his or her ability to provide informed consent, comply with the study protocol, which might confound the interpretation of the study results or put the person at undue risk.

The study site will be provided placebo and TRU NIAGEN capsules, each labeled with the protocol number, blinded product code, expiration date, batch number, the statement "For Investigational Use Only" and a space to write the subject's initials, screen and date dispensed.