{"url":"https://whatshealthyandwhy.com/nicotinamide-riboside/nad-precursor-and-cellular-energy","path":"/nicotinamide-riboside/nad-precursor-and-cellular-energy","alternates":{"json":"https://whatshealthyandwhy.com/api/articles/nicotinamide-riboside/nad-precursor-and-cellular-energy.json","markdown":"https://whatshealthyandwhy.com/nicotinamide-riboside/nad-precursor-and-cellular-energy.md"},"topic":{"slug":"nicotinamide-riboside","name":"Nicotinamide Riboside","url":"https://whatshealthyandwhy.com/nicotinamide-riboside"},"slug":"nad-precursor-and-cellular-energy","order":1,"title":"NAD+ Precursor and Cellular Energy","question":"Does taking nicotinamide riboside (NR) improve health?","answer":"NR may modestly help some measures such as blood pressure, but a review of 25 studies found few clinically relevant effects.","description":"How nicotinamide riboside raises NAD+ levels, supports mitochondrial function, cardiovascular health, and healthy aging — and what human clinical trials actually show","confidence":2,"confidenceNote":"Three randomized trials (24, 40 and 30 people) raised NAD+, but a review of 25 published human studies found few clinically relevant effects.","evidenceSummary":{"rctCount":3,"observationalCount":0,"metaAnalysisCount":1,"totalParticipants":"~100","replicated":true,"newestStudyYear":2023},"category":{"categoryTitle":"What's Good For You","categorySlug":"good-for-you","subcategoryName":"Supplements & Vitamins","subcategorySlug":"supplements","url":"https://whatshealthyandwhy.com/explore/good-for-you/supplements"},"actions":["A reasonable starting dose is 300–500 mg/day; most trials used 300–1,000 mg/day, and many people take it in the morning.","If cost matters, NR is typically cheaper than NMN, and no head-to-head human trial shows either is better [5].","Do not count on food for this: NR in milk, yeast and some vegetables is negligible compared with supplement doses."],"cautions":["NR was well tolerated in the trials described [2][4], and no serious adverse events were seen in the 12-week trial of 2,000 mg/day [3].","The trials described here were small (40 and 30 people in two of them) and short (30 days to 12 weeks), so long-term effects are unknown [3][4].","NR did not improve insulin sensitivity in obese men at 2,000 mg/day, so do not rely on it for metabolic problems [3]."],"simpleText":"Nicotinamide riboside (NR) is a form of vitamin B3 that your body uses to make NAD+ — a coenzyme essential for energy production, DNA repair, and the regulation of hundreds of cellular processes. NAD+ levels decline significantly with age, and this decline is associated with reduced mitochondrial efficiency, increased fatigue, and greater susceptibility to metabolic dysfunction [1]. NR is one of the most direct and well-studied ways to replenish NAD+ through diet or supplementation. Multiple human clinical trials confirm that oral NR reliably raises blood NAD+ levels with an excellent safety profile [2], making it one of the more evidence-backed longevity-focused supplements available today.","mediumText":"How Nicotinamide Riboside Works\n\nNR belongs to a family of NAD+ precursors that includes niacin (vitamin B3), nicotinamide (NAM), and nicotinamide mononucleotide (NMN). What distinguishes NR is where it enters the biosynthetic pathway: it is converted directly to NMN inside cells, then to NAD+ — bypassing several rate-limiting steps that slow conversion from niacin or nicotinamide [1].\n\nThe NAD+ problem with aging is well documented. Studies in humans and animals consistently show that NAD+ levels in muscle, skin, and blood fall by 40–60% between early adulthood and middle age. This decline reflects both slowing synthesis and faster consumption by inflammatory enzymes — particularly CD38, which accumulates with chronic low-grade inflammation as we age. Restoring NAD+ is hypothesized to support mitochondrial energy production, sirtuin enzyme activity (which regulates cellular repair and stress responses), and PARP enzymes that fix DNA strand breaks.\n\nBioavailability. The foundational human study showed that a single oral dose of NR raises blood NAD+ metabolites in a dose-dependent manner — demonstrating that NR survives digestion and is absorbed intact through the gut [1]. This was an important finding because earlier debate existed about whether orally administered NAD+ precursors could survive the digestive tract.\n\nWhat the Science Shows\n\nNAD+ elevation. This is the most consistent finding across human trials. Multiple studies show that NR at doses of 250–2,000 mg/day reliably raises blood NAD+ metabolites, including NAM (nicotinamide), NAAD (nicotinic acid adenine dinucleotide), and MeNAM (methyl-NAM), within days of starting supplementation [1][2][3]. The effect is dose-dependent and sustained with ongoing use.\n\nCardiovascular and blood pressure support. A crossover RCT in 24 healthy adults aged 55–79 found that 1,000 mg/day NR (500 mg twice daily) for 6 weeks elevated blood NAD+ metabolites by approximately 60% above placebo levels [2]. Exploratory analysis showed systolic blood pressure trends lower in the NR group, an effect the research team has followed up with subsequent targeted trials. While not the primary outcome, these cardiovascular signals have generated significant research interest.\n\nNeurological applications. The NADPARK trial — a randomized phase I study in 30 people with early Parkinson's disease — showed that 1,000 mg/day NR for 30 days significantly increased cerebral NAD+ levels, measured by 31P MRS brain imaging [4]. Brain metabolic activity patterns also shifted in NR-treated participants. While this was a safety/pharmacokinetics trial not powered for clinical outcomes, the finding that oral NR can cross the blood-brain barrier and raise central nervous system NAD+ is significant for research into neurodegenerative diseases.\n\nMetabolic effects in obesity. A 12-week RCT in 40 obese men using a high dose of 2,000 mg/day NR found that blood NAD+ metabolites rose substantially, and body composition (lower fat mass, higher lean mass) shifted modestly in the NR group [3]. However, insulin sensitivity and primary metabolic measures did not improve significantly, suggesting that NAD+ restoration alone may not overcome the metabolic dysfunction of obesity without accompanying lifestyle changes.\n\nNR vs. NMN: Choosing a NAD+ Precursor\n\nNR and NMN are the two most popular NAD+ precursors, and they are closely related — NR is converted to NMN inside cells before being used to make NAD+. Key differences:\n\n- Pathway. NMN is one step closer to NAD+. NR needs one extra enzymatic step (phosphorylation to NMN) inside cells.\n- Research history. NR has a slightly longer human clinical trial record; NMN trials have accelerated since 2020.\n- Cost. NR supplements are typically less expensive than NMN.\n- Dosing. Human trials for NR have used 250–2,000 mg/day; NMN trials most often use 250–600 mg/day.\n\nBoth precursors reliably raise blood NAD+ metabolites in humans. The honest answer from current evidence is that no head-to-head trial in humans has established superiority of one over the other for any clinical outcome [5]. Choice often comes down to cost, availability, and individual response.\n\nPractical Guidance\n\nDosage. Most human trials have used 300–1,000 mg/day. The crossover RCT showing cardiovascular trends used 1,000 mg/day [2]. A dose of 300–500 mg/day represents a reasonable starting point. The Parkinson's trial used 1,000 mg/day with good tolerability [4].\n\nTiming. NAD+ is involved in circadian rhythm regulation, so many people take NR in the morning. Food does not appear to significantly affect absorption.\n\nSafety. In the human trials described here, NR was well tolerated at doses up to 2,000 mg/day [2][3][4], and no serious adverse events due to NR were observed in the 12-week trial at that dose [3]. Some people report mild flushing or GI discomfort at higher doses — unlike niacin, NR does not typically cause the pronounced skin flushing associated with high-dose niacin [5].\n\nFood sources. NR is found naturally in cow's milk, yeast, and some vegetables, but dietary amounts are negligible compared to supplemental doses. Supplementation is the only practical way to achieve NAD+-raising levels.\n\nSee our NMN page for the related NAD+ precursor, and our mitochondrial health page for broader context on cellular energy support.","deepText":"Evidence Review\n\nFoundational Bioavailability Study (Trammell et al., 2016)\n\nPublished in Nature Communications, this was the first study to rigorously demonstrate oral bioavailability of NR in humans [1]. In a crossover design, healthy adults received single doses of NR and had blood and urine collected over 9 hours. NAD+ metabolites — including NAD+, NAAD, ADPR, and methylated NAM metabolites — rose significantly in blood and urine following NR ingestion compared to vehicle control. The study also demonstrated that NR, unlike NAM or niacin, does not rely on hepatic conversion before reaching the bloodstream, raising the possibility of more direct tissue delivery. This study established the pharmacokinetic foundation for subsequent chronic dosing trials. Key limitation: single-dose design with a small human cohort; full chronic dosing effects were not assessed.\n\nCrossover RCT in Healthy Older Adults (Martens et al., 2018)\n\nThis randomized, double-blind, placebo-controlled crossover trial enrolled 24 healthy adults aged 55–79 years [2]. Participants received 1,000 mg/day NR (500 mg twice daily as NIAGEN®) or placebo for 6 weeks, then crossed over after a washout period. Primary outcomes were whole-blood NAD+ metabolites; secondary outcomes included blood pressure, arterial stiffness, and markers of systemic inflammation. Results: whole-blood NAD+ metabolites rose by approximately 60% in the NR phase compared to placebo (p<0.001). Systolic blood pressure was 3.9 mmHg lower in the NR phase (p<0.05 in a subset of participants with elevated blood pressure at baseline). Pulse wave velocity, a measure of arterial stiffness, showed a non-significant trend toward improvement. No adverse events occurred. This remains one of the most important NR RCTs because of its rigorous crossover design, clean safety data, and the cardiovascular signal it generated in an older adult population.\n\nObese Men RCT (Dollerup et al., 2018)\n\nThis 12-week, randomized, double-blind, placebo-controlled trial enrolled 40 obese but otherwise healthy men (BMI 28–40) [3]. Participants received 2,000 mg/day NR or placebo. Primary outcomes were insulin sensitivity (hyperinsulinemic-euglycemic clamp) and whole-body glucose metabolism. Secondary outcomes included body composition (MRI), skeletal muscle mitochondrial function, and blood lipids. Key findings: blood NAD+ metabolites rose substantially in the NR group (whole-blood NAM increased ~50%). Body composition analysis showed a trend toward lower fat mass and higher lean mass in the NR group at 12 weeks, though this did not reach statistical significance for the primary MRI-based lean mass measure. Critically, NR did not improve insulin sensitivity or glucose metabolism compared to placebo. Lipid profiles were similar between groups. No serious adverse events occurred, confirming tolerability at 2,000 mg/day — the highest dose tested in a controlled chronic human trial. The negative metabolic findings suggest that NAD+ repletion alone may be insufficient to reverse obesity-associated insulin resistance, an important calibration of expectations for this supplement.\n\nNADPARK Parkinson's Disease Trial (Brakedal et al., 2022)\n\nThis randomized, double-blind, phase I trial enrolled 30 people with early-stage Parkinson's disease who were not yet on dopaminergic therapy [4]. Participants received either 1,000 mg/day NR or placebo for 30 days. The primary outcome was cerebral NAD+ concentration measured by 31-phosphorus magnetic resonance spectroscopy (31P MRS) — a non-invasive method for imaging brain metabolism. Secondary outcomes included mitochondrial function markers and clinical Parkinson's disease rating scales. Results: cerebral NAD+ rose significantly in the NR group compared to placebo (mean increase ~%10, p<0.05). Cerebrospinal fluid analysis confirmed NR metabolites reached the CNS. Metabolomic analysis of CSF and blood revealed changes in TCA cycle intermediates and one-carbon metabolism pathways consistent with improved mitochondrial function in the NR group. Motor outcomes on the UPDRS scale were not significantly different at 30 days — an expected finding given the short duration and early disease stage. No serious adverse events occurred. This trial is notable as the first to demonstrate that orally administered NR can raise NAD+ in the living human brain, establishing proof of concept for NAD+ repletion as a neurological intervention. Larger trials with longer duration are underway.\n\nCritical Evidence Review (Damgaard and Treebak, 2023)\n\nThis review critically assessed the 25 published research articles on human NR supplementation [5], aiming to identify poorly founded claims and clarify the actual future potential of NR. Key conclusions: (1) Collectively, oral NR supplementation has displayed few clinically relevant effects. (2) There is an unfortunate tendency in the literature to exaggerate the importance and robustness of reported effects. (3) Even so, NR may play a role in the reduction of inflammatory states and has shown some potential in the treatment of diverse severe diseases. This honest assessment is important context for interpreting the enthusiasm around NR: the clinical health consequences of NAD+ repletion in humans remain an active area of investigation.\n\nOverall Evidence Assessment …","deepTruncated":true,"references":[{"id":"1","title":"Nicotinamide riboside is uniquely and orally bioavailable in mice and humans","authors":"Trammell SA, Schmidt MS, Weidemann BJ, Redpath P, Jaksch F, Dellinger RW, Li Z, Abel ED, Migaud ME, Brenner C","year":2016,"journal":"Nature Communications","pmid":"27721479","url":"https://pubmed.ncbi.nlm.nih.gov/27721479/"},{"id":"2","title":"Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults","authors":"Martens CR, Denman BA, Mazzo MR, Armstrong ML, Reisdorph N, McQueen MB, Chonchol M, Seals DR","year":2018,"journal":"Nature Communications","pmid":"29599478","url":"https://pubmed.ncbi.nlm.nih.gov/29599478/"},{"id":"3","title":"A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects","authors":"Dollerup OL, Christensen B, Svart M, Schmidt MS, Sulek K, Ringgaard S, Stødkilde-Jørgensen H, Møller N, Brenner C, Treebak JT, Jessen N","year":2018,"journal":"American Journal of Clinical Nutrition","pmid":"29992272","url":"https://pubmed.ncbi.nlm.nih.gov/29992272/"},{"id":"4","title":"The NADPARK study: A randomized phase I trial of nicotinamide riboside supplementation in Parkinson's disease","authors":"Brakedal B, Dölle C, Riemer F, Ma Y, Nido GS, Skeie GO, Craven AR, Schwarzlmüller T, Brekke N, Diab J, Sverkeli L, Skjeie V, Varhaug K, Tysnes OB, Peng S, Haugarvoll K, Ziegler M, Grüner R, Eidelberg D, Tzoulis C","year":2022,"journal":"Cell Metabolism","pmid":"35235774","url":"https://pubmed.ncbi.nlm.nih.gov/35235774/"},{"id":"5","title":"What is really known about the effects of nicotinamide riboside supplementation in humans","authors":"Damgaard MV, Treebak JT","year":2023,"journal":"Science Advances","pmid":"37478182","url":"https://pubmed.ncbi.nlm.nih.gov/37478182/"}],"wordCount":1780,"source":{"path":"src/content/topics/nicotinamide-riboside/nad-precursor-and-cellular-energy.md"},"citeAs":"“Does taking nicotinamide riboside (NR) improve health?.” What's Healthy and Why. https://whatshealthyandwhy.com/nicotinamide-riboside/nad-precursor-and-cellular-energy","notice":"General information backed by peer-reviewed research, not medical advice."}