Short-term nicotinamide riboside treatment improves muscle quality and function in mice and increases cellular energetics and differentiating capacity of myogenic progenitors

NAD+ Precursors Nicotinamide Mononucleotide (NMN) and Nicotinamide Riboside (NR): Potential Dietary Contribution to Health

PURPOSE OF REVIEW

NAD+ is a vital molecule that takes part as a redox cofactor in several metabolic reactions besides being used as a substrate in important cellular signaling in regulation pathways for energetic, genotoxic, and infectious stress. In stress conditions, NAD+ biosynthesis and levels decrease as well as the activity of consuming enzymes rises. Dietary precursors can promote NAD+ biosynthesis and increase intracellular levels, being a potential strategy for reversing physiological decline and preventing diseases. In this review, we will show the biochemistry and metabolism of NAD+ precursors NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide), the latest findings on their beneficial physiological effects, their interplay with gut microbiota, and the future perspectives for research in nutrition and food science fields.

RECENT FINDINGS

NMN and NR demonstrated protect against diabetes, Alzheimer disease, endothelial dysfunction, and inflammation. They also reverse gut dysbiosis and promote beneficial effects at intestinal and extraintestinal levels. NR and NMN have been found in vegetables, meat, and milk, and microorganisms in fermented beverages can also produce them. NMN and NR can be obtained through the diet either in their free form or as metabolites derivate from the digestion of NAD+. The prospection of NR and NMN to find potential food sources and their dietary contribution in increasing NAD+ levels are still an unexplored field of research. Moreover, it could enable the development of new functional foods and processing strategies to maintain and enhance their physiological benefits, besides the studies of new raw materials for extraction and biotechnological development.

Nicotinamide Riboside, a Promising Vitamin B3 Derivative for Healthy Aging and Longevity: Current Research and Perspectives

Many studies have suggested that the oxidized form of nicotinamide adenine dinucleotide (NAD+) is involved in an extensive spectrum of human pathologies, including neurodegenerative disorders, cardiomyopathy, obesity, and diabetes. Further, healthy aging and longevity appear to be closely related to NAD+ and its related metabolites, including nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). As a dietary supplement, NR appears to be well tolerated, having better pharmacodynamics and greater potency. Unfortunately, NR is a reactive molecule, often unstable during its manufacturing, transport, and storage. Recently, work related to prebiotic chemistry discovered that NR borate is considerably more stable than NR itself. However, immediately upon consumption, the borate dissociates from the NR borate and is lost in the body through dilution and binding to other species, notably carbohydrates such as fructose and glucose. The NR left behind is expected to behave pharmacologically in ways identical to NR itself. This review provides a comprehensive summary (through Q1 of 2023) of the literature that makes the case for the consumption of NR as a dietary supplement. It then summarizes the challenges of delivering quality NR to consumers using standard synthesis, manufacture, shipping, and storage approaches. It concludes by outlining the advantages of NR borate in these processes.

What is really known about the effects of nicotinamide riboside supplementation in humans

Nicotinamide riboside is a precursor to the important cofactor nicotinamide adenine dinucleotide and has elicited metabolic benefits in multiple preclinical studies. In 2016, the first clinical trial of nicotinamide riboside was conducted to test the safety and efficacy of human supplementation. Many trials have since been conducted aiming to delineate benefits to metabolic health and severe diseases in humans. This review endeavors to summarize and critically assess the 25 currently published research articles on human nicotinamide riboside supplementation to identify any poorly founded claims and assist the field in elucidating the actual future potential for nicotinamide riboside. Collectively, oral nicotinamide riboside supplementation has displayed few clinically relevant effects, and there is an unfortunate tendency in the literature to exaggerate the importance and robustness of reported effects. Even so, nicotinamide riboside may play a role in the reduction of inflammatory states and has shown some potential in the treatment of diverse severe diseases.

Nicotinamide riboside improves muscle mitochondrial biogenesis, satellite cell differentiation, and gut microbiota in a twin study

Nicotinamide adenine dinucleotide (NAD+) precursor nicotinamide riboside (NR) has emerged as a promising compound to improve obesity-associated mitochondrial dysfunction and metabolic syndrome in mice. However, most short-term clinical trials conducted so far have not reported positive outcomes. Therefore, we aimed to determine whether long-term NR supplementation boosts mitochondrial biogenesis and metabolic health in humans. Twenty body mass index (BMI)-discordant monozygotic twin pairs were supplemented with an escalating dose of NR (250 to 1000 mg/day) for 5 months. NR improved systemic NAD+ metabolism, muscle mitochondrial number, myoblast differentiation, and gut microbiota composition in both cotwins. NR also showed a capacity to modulate epigenetic control of gene expression in muscle and adipose tissue in both cotwins. However, NR did not ameliorate adiposity or metabolic health. Overall, our results suggest that NR acts as a potent modifier of NAD+ metabolism, muscle mitochondrial biogenesis and stem cell function, gut microbiota, and DNA methylation in humans irrespective of BMI.

Deletion of Nmnat1 in Skeletal Muscle Leads to the Reduction of NAD+ Levels but Has No Impact on Skeletal Muscle Morphology and Fiber Types

Nicotinamide adenine dinucleotide (NAD⁺) is a coenzyme that mediates many redox reactions in energy metabolism. NAD⁺ is also a substrate for ADP-ribosylation and deacetylation by poly (ADP-ribose) polymerase and sirtuin, respectively. Nicotinamide mononucleotide adenylyltransferase 1 (Nmnat1) is a NAD⁺ biosynthesizing enzyme found in the nucleus. Recent research has shown that the maintaining NAD⁺ levels is critical for sustaining muscle functions both in physiological and pathological conditions. However, the role of Nmnat1 in skeletal muscle remains unexplored. In this study, we generated skeletal muscle-specific Nmnat1 knockout (M-Nmnat1 KO) mice and investigated its role in skeletal muscle. We found that NAD⁺ levels were significantly lower in the skeletal muscle of M-Nmnat1 KO mice than in control mice. M-Nmnat1 KO mice, in contrast, had similar body weight and normal muscle histology. Furthermore, the distribution of muscle fiber size and gene expressions of muscle fiber type gene expression were comparable in M-Nmnat1 KO and control mice. Finally, we investigated the role of Nmnat1 in muscle regeneration using cardiotoxin-induced muscle injury model, but muscle regeneration appeared almost normal in M-Nmnat1 KO mice. These findings imply that Nmnat1 has a redundancy in the pathophysiology of skeletal muscle.

Increased Dietary Niacin Intake Improves Muscle Strength, Quality, and Glucose Homeostasis in Adults over 40 Years of Age

BACKGROUND AND AIMS

Age-related loss of skeletal muscle mass and strength begins at 40 years of age, and limited evidence suggests that niacin supplementation increases levels of nicotinamide adenine dinucleotide in mouse muscle tissue. In addition, skeletal muscle has a key role in the body's processing of glucose. Therefore, this study aimed to investigate the relationship between dietary niacin and skeletal muscle mass, strength, and glucose homeostasis in people aged 40 years and older.

METHODS

This study was an American population-based cross-sectional analysis using data from the National Health and Nutrition Examination Survey (NHANES). Considering that some outcomes are only measured in specific survey cycles and subsamples, we established three data sets: a grip strength dataset (2011-2014, n=3772), a body mass components dataset (2011-2018, n=3279), and a glucose homeostasis dataset (1999-2018, n=9189). Dietary niacin and covariates were measured in all survey cycles. Linear regression or logistic regression models that adjusted for several main covariates, such as physical activity and diet, was used to evaluate the relationship between dietary niacin and grip strength, total lean mass, appendicular lean mass, total fat, trunk fat, total bone mineral content, homeostasis model assessment of insulin resistance (HOMA-IR), fasting blood glycose, fasting insulin and sarcopenia risk. Subgroup analyses, a trend test, an interaction test, and a restricted cubic spline were used for further exploration.

RESULTS

Higher dietary niacin intake was significantly correlated with higher grip strength (β 0.275, 95% confidence intervals [CI] 0.192-0.357), higher total lean mass (β 0.060, 95% CI 0.045-0.074), higher appendicular lean mass (β 0.025, 95% CI 0.018-0.033), and higher total bone mineral content (β 0.005, 95% CI 0.004-0.007). By contrast, higher dietary niacin intake was significantly associated with lower total fat (β -0.061, 95% CI -0.076 to -0.046), lower trunk fat (β -0.041, 95% CI -0.050 to -0.032) and lower sarcopenia risk (OR 0.460, 95% CI 0.233 to 0.907). In addition, dietary niacin significantly reduced HOMA-IR, fasting blood glucose (in participants without diabetes), and fasting insulin (p <0.05).

CONCLUSION

Niacin is associated with improved body composition (characterized by increased muscle mass and decreased fat content) and improved glucose homeostasis in dietary doses. Dietary niacin supplementation is a feasible way to alleviate age-related muscular loss.

Intravenous Nicotinamide Riboside Administration Has a Cardioprotective Effect in Chronic Doxorubicin-Induced Cardiomyopathy

Doxorubicin, which is widely used to treat a broad spectrum of malignancies, has pronounced dose-dependent side effects leading to chronic heart failure development. Nicotinamide riboside (NR) is one of the promising candidates for leveling the cardiotoxic effect. In the present work, we performed a comparative study of the cardioprotective and therapeutic actions of various intravenous NR administration modes in chronic doxorubicin-induced cardiomyopathy in Wistar rats. The study used 60 mature male SPF Wistar rats. The animals were randomized into four groups (a control group and three experimental groups) which determined the doxorubicin (intraperitoneally) and NR (intravenous) doses as well as the specific modes of NR administration (combined, preventive). We demonstrated the protective effect of NR on the cardiovascular system both with combined and preventive intravenous drug administration, which was reflected in a fibrous tissue formation decrease, reduced fractional-shortening decrease, and better antioxidant system performance. At the same time, it is important to note that the preventive administration of NR had a more significant protective effect on the animal organism as a whole. This was confirmed by better physical activity parameters and vascular bed conditions. Thus, the data obtained during the study can be used for further investigation into chronic doxorubicin-induced cardiomyopathy prevention and treatment approaches.

Nicotinamide Riboside Supplementation to Suckling Male Mice Improves Lipid and Energy Metabolism in Skeletal Muscle and Liver in Adulthood

Nicotinamide riboside, an NAD⁺ precursor, has been attracting a lot of attention in recent years due to its potential benefits against multiple metabolic complications and age-related disorders related to NAD⁺ decline in tissues. The metabolic programming activity of NR supplementation in early-life stages is much less known. Here, we studied the long-term programming effects of mild NR supplementation during the suckling period on lipid and oxidative metabolism in skeletal muscle and liver tissues using an animal model. Suckling male mice received a daily oral dose of NR or vehicle (water) from day 2 to 20 of age, were weaned at day 21 onto a chow diet, and at day 90 were distributed to either a high-fat diet (HFD) or a normal-fat diet for 10 weeks. Compared to controls, NR-treated mice were protected against HFD-induced triacylglycerol accumulation in skeletal muscle and displayed lower triacylglycerol levels and steatosis degree in the liver and distinct capacities for fat oxidation and decreased lipogenesis in both tissues, paralleling signs of enhanced sirtuin 1 and AMP-dependent protein kinase signaling. These pre-clinical findings suggest that mild NR supplementation in early postnatal life beneficially impacts lipid and energy metabolism in skeletal muscle and liver in adulthood, serving as a potential preventive strategy against obesity-related disorders characterized by ectopic lipid accumulation.

Nicotinamide riboside relieves the severity of experimental necrotizing enterocolitis by regulating endothelial function via eNOS deacetylation

BACKGROUND

Nicotinamide adenine dinucleotide (NAD+) is involved in regulating oxidative stress. Although NAD+ is associated with various health issues, its role in the intestinal microcirculation in necrotizing enterocolitis (NEC) remains to be confirmed. In the current study, we explored whether nicotinamide riboside (NR), a natural NAD + precursor, ameliorates the severity of NEC through endothelial nitric oxide synthase(eNOS) signaling.

METHODS

A mouse experimental NEC model was induced by formula gavage and hypoxia in full-term mouse pups. Intestinal endothelial cells (MIMECs) were isolated and subjected to stress using tumor necrosis factor (TNF)-α. NR was administered to assess the intestinal microcirculation and lipid peroxidation levels and to explore the involved signaling pathways.

RESULTS

NAD + levels were reduced after induction of NEC stress, which was associated with intestinal injury. NR administration promoted NAD + levels, attenuated oxidative stress and relieved the symptoms of experimental NEC, which were relevant to increased intestinal microcirculatory perfusion through the sirtuin (SIRT) 1 pathway in experimental NEC mice. However, this improvement was not found in eNOS-knockout mice. Consistently, MIMECs exposed to TNFα showed decreased SIRT1 activity associated with increased eNOS acetylation, which could bring about endothelial dysfunction due to limited nitric oxide production. NR administration increased the NAD + content and repressed the production of reactive oxygen species (ROS) in MIMECs under TNFα stress. NR also promoted SIRT1 activity and accordingly suppressed the eNOS acetylation levels under TNFα stress.

CONCLUSION

The current data indicate that NR administration improves the survival of experimental NEC mice via SIRT1-associated eNOS acetylation/deacetylation modulation, which is implicated in endothelial dysfunction. Although NR is commonly found in the human diet, it may also be a promising strategy for NEC treatment because of its pathogenic association with NEC.

Strategies to protect against age-related mitochondrial decay: Do natural products and their derivatives help?

Mitochondria serve vital roles critical for overall cellular function outside of energy transduction. Thus, mitochondrial decay is postulated to be a key factor in aging and in age-related diseases. Mitochondria may be targets of their own decay through oxidative damage. However, treating animals with antioxidants has been met with only limited success in rejuvenating mitochondrial function or in increasing lifespan. A host of nutritional strategies outside of using traditional antioxidants have been devised to promote mitochondrial function. Dietary compounds are under study that induce gene expression, enhance mitochondrial biogenesis, mitophagy, or replenish key metabolites that decline with age. Moreover, redox-active compounds may now be targeted to mitochondria which improve their effectiveness. Herein we review the evidence that representative dietary effectors modulate mitochondrial function by stimulating their renewal or reversing the age-related loss of key metabolites. While in vitro evidence continues to accumulate that many of these compounds benefit mitochondrial function and/or prevent their decay, the results using animal models and, in some instances human clinical trials, are more mixed and sometimes even contraindicated. Thus, further research on optimal dosage and age of intervention are warranted before recommending potential mitochondrial rejuvenating compounds for human use.

Nicotinamide Riboside Neutralizes Hypothalamic Inflammation and Increases Weight Loss Without Altering Muscle Mass in Obese Rats Under Calorie Restriction: A Preliminary Investigation

Obesity treatments, such as calorie restriction (CR), eventually lead to muscle wasting and higher rates of neuroinflammation, whereas hypothalamic inflammatory conditions impair body weight (BW) control. Nicotinamide riboside (NR) has been proposed against obesity but with little evidence on skeletal muscle tissue (SMT) and neuroinflammation. Therefore, we aimed to investigate the effects of CR on SMT and on hypothalamic inflammatory biomarkers in obese adult male Wistar rats, and whether NR supplementation alone or in combination with CR affects these parameters. Obesity was induced in rats through a cafeteria diet for 6 weeks. After that, a group of obese rats was exposed to CR, associated or not associated with NR supplementation (400 mg/kg), for another 4 weeks. As a result, obese rats, with or without CR, presented lower relative weight of SMT when compared with eutrophic rats. Rats under CR presented lower absolute SMT weight compared with obese and eutrophic rats, in addition to presenting elevated hypothalamic levels of TNF-α. NR supplementation, in all groups, enhanced weight loss and increased relative weight of the SMT. Furthermore, in animals under CR, NR reversed increases TNF-α levels in the hypothalamus. In this study, these data, although succinct, are the first to evidence the effects of NR on SMT and neuroinflammation when associated with CR, especially in obesity conditions. Therefore, this provides preliminary support for future studies in this investigative field. Furthermore, NR emerges as a potential adjuvant for preventing muscle mass loss in the weight loss processes.