Complete Guide to NAD+
Aging is a natural, gradual process leading towards decreased normal bodily functions at a moderate rate. Several endogenous hormones and proteins decline in the body as people age. One such protein, NAD+, which is essential for building energy and a youthful life, also declines as people grow. It is scientifically proven that by the time humans reach middle age, the concentrations of NAD+ reduce to half of its normal levels, resulting in lower bodily functions (1).
There are several hypotheses suggesting why the levels of NAD+ decline with age, ranging from reduced synthesis to increased hydrolysis of Nicotinamide Adenine Dinucleotide, however that doesn’t mean there is no way to combat it.
There are NAD+ peptides and supplements available to counteract this situation and help maintain Nicotinamide Adenine Dinucleotide levels in the body, thereby fighting aging and inducing longevity.
What is NAD+?
NAD+ is an acronym for Nicotinamide Adenine Dinucleotide, which is an essential endogenous nucleotide that is present in all living organisms. NAD+ is vital to primary bodily functions such as metabolism and energy production, DNA repair, acts as a secondary messenger via calcium dependent signaling mechanism and serves as an immunoregulatory component (2).
NAD+ is synthesized in the body via the de novo mechanism of converting the amino acid tryptophan through several enzymatic steps. There are five key components to NAD+ synthesis including tryptophan, nicotinamide, nicotinic acid, nicotinamide riboside and nicotinamide mononucleotide (3).
Once synthesized, is used in over 500 enzymatic reactions and cellular processes (12) to aid metabolic activities in humans. Essentially, it acts as a coenzyme in redox functions and gets converted to NADH, which is then involved in other metabolic pathways (3).
NAD+ Discovery and History
NAD discovery dates back to the early 1900s, first being discovered in 1906 by Arthur Harden and William John Young as a cellular component that promotes alcohol fermentation (6,12).
During the 1930s, scientist Elvehjem identified nicotinic acid and nicotinamide as vitamin precursors during the research studies. Further studies in yeast and fungi to study the biosynthesis of NAD+ in eukaryotic organisms revealed that nicotinamide riboside is a NAD+ precursor (4).
In 1936, scientist Warburg demonstrated that NAD is a key component for redox reactions and suggested the nomenclature “NAD” refers to the same chemical backbone regardless of the electron charge (NAD+ and NADH, which refer to the oxidized and reduced forms of NAD, respectively) (12).
Throughout the 1960s to late 1990s, additional studies were conducted on NAD and it was demonstrated how NAD+ is also involved in various enzymatic reactions involving SIRTs and PARPs, that are discussed further below.
How does it work?
Nicotinamide Adenine Dinucleotide acts as a coenzyme with three major classes of enzymes including: (A) deacetylase enzymes in the sirtuin class (SIRTs), (B) poly ADP ribose polymerase (PARPs) enzymes, and (C) cyclic ADP ribose synthetase (cADPRS).
(A) SIRTs depend on NAD+ and thereby stimulate mitochondrial homeostasis, stem cell regeneration, and prevent aging aspects such as the loss of stem cells and nerve degeneration.
(B) PARPs, composed of 17 different enzymes, act alongside NAD+ enzymes and thereby synthesize poly ADP ribose polymers leading to genome stability.
(C) cADPRS include CD38 and CD157, which are key immunological cells. cADPRS hydrolyze NAD+ thereby stimulating stem cell regeneration and DNA repair, which are important for maintaining cellular health.
The above mentioned are NAD+ dependent enzymes, which exert their effects in the body based on Nicotinamide Adenine Dinucleotide presence. Since all above three enzymes are dependent on NAD+, they compete amongst themselves for the bioavailable which may potentially affect human health.
Increased function of SIRTs, for instance, may lead to reduced PARPs activity and hence leading to weakened systems. Hence, it is critical to maintain a fine balance between the availability and consumption of NAD+ to obtain optimal effects (5).
Benefits of NAD+ Peptide
There are several advantages of NAD+ including:
- Reduces aging
- Decrease stress
- Promotes DNA repair
- Promotes healthy sleep cycles
- Elevates metabolism and induces high energy levels
- Maintains healthy cell cycle
- Acts as an immunoregulatory component
Research and Clinical studies
Leads to ‘productive aging’
As mentioned above, NAD+ has two key intermediates namely nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). Studies have shown that both these intermediates are very potent agents of promoting ‘productive aging’.
In this study (7), the normal aging mice were orally administered with the NMN intermediate for 12 months. Throughout the study, it was seen that NMN promoted NAD+ synthesis in the mice that led to healthy aging with reduced weight gain, increased energy metabolism, enhanced physical activity, improved lipid profile and other physiological effects. There were rare incidents of toxic side effects reported.
In 2015, a randomized clinical trial (9) was conducted where 30 participants aged between 55 and 80 years were enrolled in this study. The main aim was to determine the safety and efficacy of the Nicotinamide Adenine Dinucleotide supplements in improving the physiological functions in aged adults.
While the studies are not available for the public, reports (10) suggest that there are several clinical studies to support that NAD+ and its intermediates improve body mechanisms and promote healthy aging in humans.
Prevention of neurodegenerative disorders
Mitochondrial dysfunction leads to various functional limitations in electron transport chain and ATP synthesis, resulting in various neurodegenerative diseases such as Alzheimer’s.
A study (8) was conducted where aged mice were administered with NMN, NAD+ intermediate, for 3 to 12 months. The main aim of the study was to evaluate the effects on mitochondrial respiratory process, for which fluorescent NMN protein was administered amongst the subject mice.
After treatment, the mitochondrial oxygen consumption rates in the nerve and brain cells of the mice were studied. Upon analysis, it was demonstrated that mitochondrial functions had been restored in the aged mice, suggesting that NMN was immediately utilized by the cells to produce NAD+ and thereby exerted the positive effects.
Since this was the first study to analyze NAD+ effects in improving mitochondrial functions, further studies were yet to be conducted. Nonetheless, the positive results suggest that NAD+ can potentially be used as a therapeutic agent to treat neurodegenerative disorders.
Enhanced DNA repair and neuroprotection effects against ischemic stress
The main aim of this study (11) was to determine the neuroprotective effects of Nicotinamide Adenine Dinucleotide against ischemic stress-induced in mice.
For the purpose of this study, in vitro ischemic stress was induced in the neuronal cultures in rats via deprivation of oxygen and glucose for about 2 hours. NAD+ was directly replenished into the culture medium either before or after the induced ischemic stress.
After 72 hours of introducing NAD+ into the cultures, it was noticed that the DNA base excision repair activity (DNA BER), cell viability and oxidative DNA damage repair was significantly improved, irrespective of whether Nicotinamide Adenine Dinucleotide was added before or after inducing the ischemic stress.
This study was novel as direct cellular replenishment was tested for the first time, and further studies were yet to be conducted, however, the results suggest that NAD+ infusion is a promising agent in improving cellular functioning in humans.
NAD+ In vivo effects on key organs
Since is vital for several bodily functions, it is imperative that NAD+ levels be maintained at an optimal concentration. In vivo studies (12) have been conducted which demonstrate the following effects of NAD+ treatment on various key organs:
NAD+ Effects on liver
Upon treating mice with the NAD+ peptide and stimulating increase in Nicotinamide Adenine Dinucleotide levels up to normal concentrations, it demonstrated positive effects such as preventing obesity and alcoholic hepatitis, while improving glucose homeostasis and overall liver health.
NAD+ Effects on kidney
When aged mice kidney was treated with supplements, it promoted SIRTs activity, which produced neuroprotective effects against glucose-induced kidney cell hypertrophy. Furthermore, when treated with NMN, NAD+ intermediate, it promoted neuroprotective effects against cisplatin-induced kidney injury.
Upon treating aged mice with NMN with a daily dose of 500 mg/kg bodyweight for 7 days, via intraperitoneal route, it led to increased ATP (energy) production, reduced inflammation and elevated mitochondrial functions.
Nicotinamide Adenine Dinucleotide deficiency leads to reduced SIRT activity which causes reduced energy production and aortic constriction.
When mice were treated with 500 mg/kg body weight dose of NMN via intraperitoneal route 30 minutes before their ischemia, it produced a cardioprotective function against ischemic injury and improved cardiac functions.
Potential treatment for COVID-19
Recent investigations of the ongoing Coronavirus cases have demonstrated that infections caused by the SARS-CoV-2 led to dysregulation of NAD+ and PARPs expression, stating that there are irregularities in NAD+ synthesis and utilization, and in gene expressions.
This suggests that upon boosting the levels of NAD+ in the body, it may help restore the Nicotinamide Adenine Dinucleotide imbalance and regulate PARPs activity, thereby leading to increased immunity towards SARS-Cov-2 (13,14).
Pilot clinical studies have begun as of January 2021 where 60 patients will be enrolled in a randomized, parallel study where all participants will receive a low dose of naltrexone and NAD+ for 12 weeks. Naltrexone is an opiate antagonist used to treat patients suffering from withdrawal symptoms (15). The main purpose of this study (16) is to examine the effects of naltrexone and NAD+ in the treatment of patients suffering from post-COVID-19 symptoms.
The design of the study is that patients will be administered with 4.5mg naltrexone daily via oral route and patches, composed of 400mg NAD+, will be worn for 4 to 6 hours once a week. Parameters examined will be the fatigue level and the quality of life during and after the study of 12 weeks. The results are awaited, and study is expected to be completed by October 2021.
What are the cons?
Available data supports that NAD+ is a safe drug and causes minimal side effects (14) when used at an optimal dose. However, there are some possible adverse effects of NAD+ caused upon administering high dose of the peptides, which include the following (17):
- Headache (common)
- Nausea, dizziness (common)
- Reduced insulin sensitivity
- Elevated oxidative stress
- Liver injury
- Parenchymal cell injury
NAD+ Peptide Profile
Bioavailability studies (18) indicate that Nicotinamide Adenine Dinucleotide is metabolized via hydrolysis in the small intestine, and is broken into NMN (nicotinamide mononucleotide) and 5-AMP via pyrophosphatase enzymes. NMN is then reduced into nicotinamide, which is the final degradation product and is then directly absorbed by human blood and tissues. These studies suggest that NAD+ is highly bioavailable and is easily absorbed and metabolized by the body.
NAD+ Peptide Dosage
Studies suggest that the optimal dose of nicotinamide riboside (NR), one of the NAD+ intermediates, is 1000 mg twice a day (2000 mg/day) via oral administration. This dose induces a two-fold increase in NAD+ in the human body, thereby exerting positive effects (14).
While NAD+ is highly bioavailable, the oral bioavailability of nicotinamide riboside is variable based on the individual profiles, primarily because NR is not highly stable in blood (14).
Nicotinamide Adenine Dinucleotide, or NAD+, is a potent peptide protein that is composed of two amino acids (hence called dinucleotide).
NAD+ is a vital endogenous peptide that is involved in more than 500 enzymatic reactions in the body and hence helps regulate vital bodily functions such as metabolism and energy production, DNA repair, acts as a secondary messenger via calcium dependent signaling mechanism and serves as an immunoregulator.
Several research studies have shown that exogenous administration of Nicotinamide Adenine Dinucleotide+ helps regulate the optimal levels of NAD+ in the body which thereby promotes healthy aging and healthy functioning of the body.
Interestingly, there is theoretical evidence indicating that NAD+ has a high potential to be used as a therapeutic agent in treating post Coronavirus symptoms. Pilot clinical studies have commenced as of January 2021 and are ongoing to confirm whether this theory proves to be practically effective in human volunteers.
While research studies on Nicotinamide Adenine Dinucleotide have been ongoing for more than 100 years now, post its discovery, further approaches are still being taken to fully explore all biological effects and mechanisms of NAD+ in the human body.
1. Schultz, Michael B, and David A Sinclair. “Why NAD(+) Declines during Aging: It’s Destroyed.” Cell metabolism vol. 23,6 (2016): 965-966. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5088772/
2. Braidy N, Liu Y. NAD+ therapy in age-related degenerative disorders: A benefit/risk analysis. Exp Gerontol. 2020 Apr;132:110831. doi: 10.1016/j.exger.2020.110831. https://pubmed.ncbi.nlm.nih.gov/31917996/
3. Johnson, Sean, and Shin-Ichiro Imai. “NAD + biosynthesis, aging, and disease.” F1000Research vol. 7 132. 1 Feb 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5795269/
4. Bieganowski P, Brenner C. Discoveries of nicotinamide riboside as a nutrient and conserved NRK genes establish a Preiss-Handler independent route to NAD+ in fungi and humans. Cell. 2004 May 14;117(4):495-502. https://pubmed.ncbi.nlm.nih.gov/15137942/
5. Fang, E. F., Lautrup, S., Hou, Y., Demarest, T. G., Croteau, D. L., Mattson, M. P., & Bohr, V. A. (2017). NAD+ in Aging: Molecular Mechanisms and Translational Implications. Trends in molecular medicine, 23(10), 899–916. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7494058/
6. Harden, A; Young, WJ (24 October 1906). “The alcoholic ferment of yeast-juice Part II.–The coferment of yeast-juice”. Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character. 78 (526): 369–375. https://royalsocietypublishing.org/doi/10.1098/rspb.1906.0070
7. Mills KF, Yoshida S, Stein LR, Grozio A, Kubota S, Sasaki Y, Redpath P, Migaud ME, Apte RS, Uchida K, Yoshino J, Imai SI. Long-Term Administration of Nicotinamide Mononucleotide Mitigates Age-Associated Physiological Decline in Mice. Cell Metab. 2016 Dec 13;24(6):795-806. https://pubmed.ncbi.nlm.nih.gov/28068222/
8. Long AN, Owens K, Schlappal AE, Kristian T, Fishman PS, Schuh RA. Effect of nicotinamide mononucleotide on brain mitochondrial respiratory deficits in an Alzheimer’s disease-relevant murine model. BMC Neurol. 2015 Mar 1;15:19. https://pubmed.ncbi.nlm.nih.gov/25884176/
9. Safety & Efficacy of Nicotinamide Riboside Supplementation for Improving Physiological Function in Middle-Aged and Older Adults. https://clinicaltrials.gov/ct2/show/NCT02921659
10. Braidy N, Liu Y. NAD+ therapy in age-related degenerative disorders: A benefit/risk analysis. Exp Gerontol. 2020 Apr;132:110831. https://pubmed.ncbi.nlm.nih.gov/31917996/
11. Wang S, Xing Z, Vosler PS, Yin H, Li W, Zhang F, Signore AP, Stetler RA, Gao Y, Chen J. Cellular NAD replenishment confers marked neuroprotection against ischemic cell death: role of enhanced DNA repair. Stroke. 2008 Sep;39(9):2587-95. https://pubmed.ncbi.nlm.nih.gov/18617666/
12. Rajman, Luis et al. “Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence.” Cell metabolism vol. 27,3 (2018): 529-547. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6342515/
13. Heer C, et al, Coronavirus infection and PARP expression dysregulate the NAD metabolome: An actionable component of innate immunity. Journal of Biological Chemistry. Volume 295, Issue 52, Dec 2020. https://www.jbc.org/article/S0021-9258(17)50676-6/fulltext
14. Mehmel, Mario et al. “Nicotinamide Riboside-The Current State of Research and Therapeutic Uses.” Nutrients vol. 12,6 1616. 31 May. 2020, doi:10.3390/nu12061616 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7352172/
15. Naltrexone (Oral Route). https://www.mayoclinic.org/drugs-supplements/naltrexone-oral-route/description/drg-20068408
16. Pilot Study Into LDN and NAD+ for Treatment of Patients With Post-COVID-19 Syndrome. https://clinicaltrials.gov/ct2/show/NCT04604704
17. Hwang, Eun Seong, and Seon Beom Song. “Possible Adverse Effects of High-Dose Nicotinamide: Mechanisms and Safety Assessment.” Biomolecules vol. 10,5 687. 29 Apr. 2020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7277745/
18. Cantó, Carles et al. “NAD(+) Metabolism and the Control of Energy Homeostasis: A Balancing Act between Mitochondria and the Nucleus.” Cell metabolism vol. 22,1 (2015): 31-53. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4487780/
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Dr. Marinov (MD, Ph.D.) is a researcher and chief assistant professor in Preventative Medicine & Public Health. Prior to his professorship, Dr. Marinov practiced preventative, evidence-based medicine with an emphasis on Nutrition and Dietetics. He is widely published in international peer-reviewed scientific journals and specializes in peptide therapy research.