NAD+ and Aging: What the First Human Trial of NR Supplementation Found

A double-blind, placebo-controlled crossover trial published in Nature Communications in 2018 enrolled twenty-four healthy adults aged fifty-five to seventy-nine and demonstrated that nicotinamide riboside — a naturally occurring form of vitamin B3 and a precursor to NAD+ — elevated blood NAD+ levels by approximately forty to fifty percent after six weeks at a dose of one thousand milligrams per day, with no serious adverse effects. NAD+ is the molecule at the center of cellular energy metabolism, DNA repair, and a family of proteins called sirtuins that regulate gene expression patterns associated with aging. Its concentration in human tissues declines by approximately fifty percent between the ages of forty and sixty. The question this trial asks — and partially answers — is whether that decline can be addressed with a dietary supplement. Every cell in your body runs on a molecule called NAD+ — nicotinamide adenine dinucleotide — that sits at the center of at least five hundred enzymatic reactions, shuttles electrons through the mitochondrial energy chain, fuels the DNA repair proteins that respond to strand breaks, and activates a family of regulatory enzymes called sirtuins that influence how genes are expressed in aging tissues. Between the ages of forty and sixty, NAD+ levels in human muscle, liver, and brain tissue decline by approximately fifty percent from their peak — a drop that occurs without any acute illness or defi --- Paper cited: Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ by 40 to 50 percent in healthy middle-aged and older adults Authors: Martens CR, Denman BA, Mazzo MR, Armstrong ML, Reisdorph N, McQueen MB, Chonchol M, Seals DR Journal: Nature Communications Year: 2018 DOI: 10.1038/s41467-018-03421-7 --- Subscribe for one peer-reviewed paper made practical, every Tuesday and Friday. Free guide: How to Read Your Biomarker Panel at 55+ - {{LEAD_MAGNET_URL}} --- EDUCATIONAL CONTENT - NOT MEDICAL ADVICE This video is for general educational and informational purposes only. It summarizes peer-reviewed research. It does NOT constitute: - Medical advice, diagnosis, or treatment - Recommendations to start, stop, or change any medication - Dosing instructions for supplements or interventions - A substitute for consultation with a licensed physician Before applying anything discussed: - Talk to your physician, especially if you take prescription medications (statins, metformin, blood thinners, antihypertensives, GLP-1 agonists, etc.) - Discuss interactions, contraindications, and your individual risk profile - Get baseline biomarkers before changing your regimen if relevant Specific cautions: - Intermittent fasting: not appropriate for people with diabetes (especially Type 1), history of eating disorders, pregnancy, or underweight status without medical supervision. - Strength/Zone-2 training: medical clearance recommended for cardiovascular or joint conditions before initiating new training loads. - Supplements: third-party tested products preferred; verify drug interactions. AFFILIATE DISCLOSURE (FTC compliant): Some links in the description may be affiliate links. We may earn a commission at no additional cost to you. We only feature products and tools relevant to the research discussed. AI-ASSISTED PRODUCTION: Voice narration is generated via Edge TTS (Microsoft Neural Voice). Research, scriptwriting, and review are conducted by a human editor before publication. Reviewed: 2026-09-25