Explore the vast range of titles available.

Nicotinamide riboside (NR) is a newly discovered nicotinamide adenine dinucleotide (NAD + ) precursor vitamin. A crystal form of NR chloride termed NIAGEN is generally recognized as safe (GRAS) for use in foods and the subject of two New Dietary Ingredient Notifications for use in dietary supplements. To evaluate the kinetics and dose-dependency of NR oral availability and safety in overweight, but otherwise healthy men and women, an 8-week randomized, double-blind, placebo-controlled clinical trial was conducted. Consumption of 100, 300 and 1000 mg NR dose-dependently and significantly increased whole blood NAD + (i.e., 22%, 51% and 142%) and other NAD + metabolites within 2 weeks. The increases were maintained throughout the remainder of the study. There were no reports of flushing and no significant differences in adverse events between the NR and placebo-treated groups or between groups at different NR doses. NR also did not elevate low density lipoprotein cholesterol or dysregulate 1-carbon metabolism. Together these data support the development of a tolerable upper intake limit for NR based on human data.

The decline of nicotinamide adenine dinucleotide (NAD ) with aging may elevate risk of Alzheimer's disease and related neurocognitive disorders (ADRD) by impairing cellular energy metabolism and reducing cerebral blood flow. We conducted a 12-week double-blind, randomized, placebo-controlled pilot study to evaluate the safety, tolerability, and preliminary efficacy of the NAD precursor, nicotinamide riboside (NR; 500 mg b.i.d.), for enhancing cognitive function and cerebral perfusion in older adults with mild cognitive impairment (MCI). 52 participants (33 females, 19 males) were randomized and 42 completed the trial (NR = 22, placebo = 20). Adherence was similar between groups (NR = 85 ± 20% vs. placebo = 91 ± 5%), with no serious adverse effects and comparable side effects. Blood NAD increased with NR (pre: 23.36 ± 1.94; post: 48.52 ± 4.12 µM) compared with placebo (pre: 24.12 ± 1.70; post: 25.14 ± 1.58 µM) with a significant treatment by time interaction (p <0.001). Cognitive function did not significantly improve, however, there was a modest increase in delayed recall memory from the WMS-IV in the NR group (interaction p = 0.062). Perfusion of the left hippocampus increased with NR (pre: 51.7 ± 3.3; post: 58.0 ± 3.8 ml/min/100g) compared with placebo (pre: 55.6 ± 2.8; post: 51.7 ± 2.3 ml/min/100g; interaction p = 0.033); however, this was not associated with the change in memory performance. These outcomes were not strongly influenced by baseline plasma pTau-217. NR is well-tolerated in older adults with MCI and may enhance perfusion of the hippocampus regardless of underlying AD pathology. However, this was not associated with improved memory performance in this short-duration trial. A larger phase-III trial over a longer treatment duration is warranted to determine the efficacy of NR for delaying cognitive impairment due to ADRD.

It has been assumed that exercise intensity variation throughout a cycling time trial (TT) occurs in alignment of various metabolic changes to prevent premature task failure. However, this assumption is based on target metabolite responses, which limits our understanding of the complex interconnection of metabolic responses during exercise. The current study characterized the metabolomic profile, an untargeted metabolic analysis, after specific phases of a cycling 4‐km TT. Eleven male cyclists performed three separated TTs in a crossover counterbalanced design, which were interrupted at the end of the fast‐start (FS, 600 ± 205 m), even‐pace (EP, 3600 ± 190 m), or end‐spurt (ES, 4000 m) phases. Blood samples were taken before any exercise and 5 min after exercise cessation, and the metabolomic profile characterization was performed using Nuclear Magnetic Resonance metabolomics. Power output (PO) was also continually recorded. There were higher PO values during the FS and ES compared to the EP (all p < 0.05), which were accompanied by distinct metabolomic profiles. FS showed high metabolite expression in TCA cycle and its related pathways (e.g., glutamate, citric acid, and valine metabolism); whereas, the EP elicited changes associated with antioxidant effects and oxygen delivery adjustment. Finally, ES was related to pathways involved in NAD turnover and serotonin metabolism. These findings suggest that the specific phases of a cycling TT are accompanied by distinct metabolomic profiles, providing novel insights regarding the relevance of specific metabolic pathways on the process of exercise intensity regulation. Highlights Untargeted metabolomic profile analysis may reveal unexplored bioenergetic pathways activated throughout a self‐paced cycling time trial. Exercise intensity variations throughout a cycling time trial are accompanied by different blood serum metabolomic profiles. The current new insights may encourage future investigation on the underpinning mechanisms of specific metabolomic profiles according to each time trial phase.

Nicotinamide riboside (NR) is in wide use as an NAD + precursor vitamin. Here we determine the time and dose-dependent effects of NR on blood NAD + metabolism in humans. We report that human blood NAD + can rise as much as 2.7-fold with a single oral dose of NR in a pilot study of one individual, and that oral NR elevates mouse hepatic NAD + with distinct and superior pharmacokinetics to those of nicotinic acid and nicotinamide. We further show that single doses of 100, 300 and 1,000 mg of NR produce dose-dependent increases in the blood NAD + metabolome in the first clinical trial of NR pharmacokinetics in humans. We also report that nicotinic acid adenine dinucleotide (NAAD), which was not thought to be en route for the conversion of NR to NAD + , is formed from NR and discover that the rise in NAAD is a highly sensitive biomarker of effective NAD + repletion. NAD + is an important coenzyme that mediates cellular metabolism and defends against stresses due to age and overnutrition. Here the authors demonstrate unique bioavailability of the NAD + precursor vitamin nicotinamide riboside (NR) in mice and humans, and show that NR safely elevates human NAD + .

The co-primary objectives of this study were to determine the human pharmacokinetics (PK) of oral NR and the effect of NR on whole blood nicotinamide adenine dinucleotide (NAD+) levels. Though mitochondrial dysfunction plays a critical role in the development and progression of heart failure, no mitochondria-targeted therapies have been translated into clinical practice. Recent murine studies have reported associations between imbalances in the NADH/NAD+ ratio with mitochondrial dysfunction in multiple tissues, including myocardium. Moreover, an NAD+ precursor, nicotinamide mononucleotide, improved cardiac function, while another NAD+ precursor, nicotinamide riboside (NR), improved mitochondrial function in muscle, liver and brown adipose. Thus, PK studies of NR in humans is critical for future clinical trials. In this non-randomized, open-label PK study of 8 healthy volunteers, 250 mg NR was orally administered on Days 1 and 2, then uptitrated to peak dose of 1000 mg twice daily on Days 7 and 8. On the morning of Day 9, subjects completed a 24-hour PK study after receiving 1000 mg NR at t = 0. Whole-blood levels of NR, clinical blood chemistry, and NAD+ levels were analyzed. Oral NR was well tolerated with no adverse events. Significant increases comparing baseline to mean concentrations at steady state (Cave,ss) were observed for both NR (p = 0.03) and NAD+ (p = 0.001); the latter increased by 100%. Absolute changes from baseline to Day 9 in NR and NAD+ levels correlated highly (R2 = 0.72, p = 0.008). Because NR increases circulating NAD+ in humans, NR may have potential as a therapy in patients with mitochondrial dysfunction due to genetic and/or acquired diseases.

Nicotinamide adenine dinucleotide (NAD+) depletion has been postulated as a contributor to the severity of COVID‐19; however, no study has prospectively characterized NAD+ and its metabolites in relation to disease severity in patients with COVID‐19. We measured NAD+ and its metabolites in 56 hospitalized patients with COVID‐19 and in two control groups without COVID‐19: (1) 31 age‐ and sex‐matched adults with comorbidities, and (2) 30 adults without comorbidities. Blood NAD+ concentrations in COVID‐19 group were only slightly lower than in the control groups (p < 0.05); however, plasma 1‐methylnicotinamide concentrations were significantly higher in patients with COVID‐19 (439.7 ng/mL, 95% CI: 234.0, 645.4 ng/mL) than in age‐ and sex‐matched controls (44.5 ng/mL, 95% CI: 15.6, 73.4) and in healthy controls (18.1 ng/mL, 95% CI 15.4, 20.8; p < 0.001 for each comparison). Plasma nicotinamide concentrations were also higher in COVID‐19 group and in controls with comorbidities than in healthy control group. Plasma concentrations of 2‐methyl‐2‐pyridone‐5‐carboxamide (2‐PY), but not NAD+, were significantly associated with increased risk of death (HR = 3.65; 95% CI 1.09, 12.2; p = 0.036) and escalation in level of care (HR = 2.90, 95% CI 1.01, 8.38, p = 0.049). RNAseq and RTqPCR analyses of PBMC mRNA found upregulation of multiple genes involved in NAD+ synthesis as well as degradation, and dysregulation of NAD+‐dependent processes including immune response, DNA repair, metabolism, apoptosis/autophagy, redox reactions, and mitochondrial function. Blood NAD+ concentrations are modestly reduced in COVID‐19; however, NAD+ turnover is substantially increased with upregulation of genes involved in both NAD+ biosynthesis and degradation, supporting the rationale for NAD+ augmentation to attenuate disease severity. Whole blood NAD+ levels were only modestly reduced in patients hospitalized with COVID‐19 but the circulating levels of NAD+ metabolites, 1‐methylnicotinamide and nicotinamide were markedly elevated. The expression levels of NAD consuming/degrading enzymes as well as of enzymes involved in NAD synthesis were markedly upregulated consistent with increased NAD+ turnover. The circulating levels of NAD+ metabolite, 2‐PY were associated with risk of death and transfer to intensive care.

Background and Objectives: Diabetic nephropathy (DN) is a major cause of end-stage renal disease, yet its molecular basis remains unclear. Nicotinamide adenine dinucleotide (NAD+) metabolism is crucial for energy regulation, redox balance, and inflammation. This study investigated the dysregulation of key NAD+ salvage enzymes (CD38, NAMPT, and SIRT1) across albuminuria stages in type 2 diabetes (T2D). Materials and Methods: A cross-sectional study was conducted on 225 participants: healthy controls (n = 45), T2D with normoalbuminuria (n = 60), microalbuminuria (n = 60), and macroalbuminuria (n = 60). Serum CD38, NAMPT, and SIRT1 were measured by ELISA, while CD38 and SIRT1 gene expression in peripheral blood mononuclear cells was analyzed by qPCR. Results: CD38 and NAMPT levels increased progressively with albuminuria, whereas SIRT1 levels declined significantly. CD38 and NAMPT correlated positively with HbA1c, creatinine, and urinary albumin-to-creatinine ratio (UACR), while SIRT1 showed inverse correlations and a positive association with eGFR. Regression analysis identified CD38 and NAMPT as independent positive predictors of albuminuria, and SIRT1 as a negative predictor. ROC analysis revealed strong diagnostic performance for CD38 (AUC = 0.89) and SIRT1 (AUC = 0.88). Conclusions: These findings highlight disrupted NAD+ salvage pathways in DN and suggest that restoring NAD+ balance, through CD38 inhibition, SIRT1 activation, or NAD+ precursor supplementation, may offer promising renoprotective strategies.

Death is likely to result in very extensive biochemical changes in all body tissues due to lack of circulating oxygen, altered enzymatic reactions, cellular degradation, and cessation of anabolic production of metabolites. These biochemical changes may provide chemical markers for helping to more accurately determine the time since death (post-mortem interval), which is challenging to establish with current observation-based methodologies. In this study blood pH and changes in concentration of six metabolites (lactic acid, hypoxanthine, uric acid, ammonia, NADH and formic acid) were examined post-mortem over a 96 hour period in blood taken from animal corpses (rat and pig) and blood from rats and humans stored in vitro. The pH and the concentration of all six metabolites changed post-mortem but the extent and rate of change varied. Blood pH in corpses fell from 7.4 to 5.1. Concentrations of hypoxanthine, ammonia, NADH and formic acid all increased with time and these metabolites may be potential markers for post-mortem interval. The concentration of lactate increased and then remained at an elevated level and changes in the concentration were different in the rat compared to the human and pig. This is the first systematic study of multiple metabolic changes post-mortem and demonstrates the nature and extent of the changes that occur, in addition to identifying potential markers for estimating post-mortem interval.

Background Approximately 70% of patients receiving neurotoxic chemotherapy (e.g., paclitaxel or vincristine) will develop chemotherapy-induced peripheral neuropathy. Despite the known negative effects of CIPN on physical functioning and chemotherapy dosing, little is known about how to prevent CIPN. The development of efficacious CIPN prevention interventions is hindered by the lack of knowledge surrounding CIPN mechanisms. Nicotinamide adenine dinucleotide (NAD + ) and cyclic-adenosine diphosphate ribose (cADPR) are potential markers of axon degeneration following neurotoxic chemotherapy, however, such markers have been exclusively measured in preclinical models of chemotherapy-induced peripheral neuropathy (CIPN). The overall objective of this longitudinal, observational study was to determine the association between plasma NAD + , cADPR, and ADPR with CIPN severity in young adults receiving vincristine or paclitaxel. Methods Young adults (18–39 years old) beginning vincristine or paclitaxel were recruited from Dana-Farber Cancer Institute. Young adults completed the QLQ-CIPN20 sensory and motor subscales and provided a blood sample prior to starting chemotherapy (T1) and at increasing cumulative vincristine (T2: 3–5 mg, T3: 7–9 mg) and paclitaxel (T2: 300–500 mg/m 2 , T3: 700–900 mg/m 2 ) dosages. NAD + , cADPR, and ADPR were quantified from plasma using mass spectrometry. Metabolite levels and QLQ-CIPN20 scores over time were compared using mixed-effects linear regression models and/or paired two-sample tests. Results Participants ( N  = 50) were mainly female (88%), white (80%), and receiving paclitaxel (78%). Sensory and motor CIPN severity increased from T1–T3 ( p  < 0.001). NAD + ( p  = 0.28), cADPR ( p  = 0.62), and ADPR ( p  = 0.005) values decreased, while cADPR/NAD + ratio increased from T1–T3 ( p  = 0.50). There were no statistically significant associations between NAD + and QLQ-CIPN20 scores over time. Conclusions To our knowledge, this is the first study to measure plasma NAD + , cADPR, and ADPR among patients receiving neurotoxic chemotherapy. Although, no meaningful changes in NAD + , cADPR, or cADPR/NAD + were observed among young adults receiving paclitaxel or vincristine. Future research in an adequately powered sample is needed to explore the clinical utility of biomarkers of axon degeneration among patients receiving neurotoxic chemotherapy to guide mechanistic research and novel CIPN treatments.

Peripheral neuropathy (PN) and accelerated biological ageing are common in colorectal cancer (CRC) patients. In vitro and in vivo studies suggest links between biological ageing, oxidative stress, and PN. This longitudinal study examined associations between markers of accelerated ageing (leukocyte telomere length (LTL) and plasma NAD + levels) and oxidative stress (protein carbonyl content (PCC)) with PN in CRC patients. Newly diagnosed CRC patients (n = 457) were recruited in a Dutch prospective cohort. LTL, plasma NAD + levels, PCC, and PN (self-reported using the EORTC QLQ-CIPN20) were measured at baseline (prior to treatment), 1-year, and 2-years follow-up. Associations between biomarkers and PN were analyzed using a confounder-adjusted linear mixed model. Longer LTL was associated with higher PN scores, including Sensory PN (SPN) and Motor PN (MPN), while lower plasma NAD + levels were linked to higher SPN complaints (β:-2.29;95%CI:-4.31,-.27). These associations were primarily driven by inter-individual changes over time. Among chemotherapy-treated patients, lower plasma NAD + levels were associated with higher total PN scores, SPN, and autonomic PN symptoms. Lower NAD + levels were longitudinally associated with higher SPN complaints, especially among those treated with chemotherapy. These findings emphasize the potential for targeting NAD + metabolism to mitigate PN in CRC.