BooHackLab

Author: Sunny Dhillon BPharm, MBA

Choosing the right NAD supplement has become increasingly important as research confirms that NAD+ levels decline by approximately 50% between young adulthood and middle age.1 This coenzyme, present in every cell, serves as the essential currency for cellular energy production, DNA repair, and the activation of longevity-associated proteins called sirtuins. When NAD+ drops, the consequences cascade across virtually every organ system.

Recent human trials over the past 4-6 years have transformed NAD+ research from promising animal studies to robust human clinical evidence. Multiple randomized controlled trials now demonstrate that NAD+ precursors can measurably raise blood NAD+ levels and influence functional outcomes. Understanding this evidence is essential for anyone considering NAD+ supplementation.

Why NAD+ Matters for Longevity

NAD+ participates in over 500 enzymatic reactions throughout your body, serving as an indispensable cofactor for energy metabolism through glycolysis and oxidative phosphorylation, DNA repair via PARP activation, and cellular signaling through sirtuin activation.

The sirtuins (SIRT1-7) regulate numerous aspects of cellular health including stress resistance, inflammation, and metabolism. However, sirtuins can only function when NAD+ is available. When NAD+ levels decline, the downstream consequences cascade:

• Mitochondrial dysfunction reduces ATP production

• Impaired DNA repair allows damage to accumulate

• Decreased sirtuin activity compromises metabolic regulation

• Cellular metabolism slows across all tissues

NMN: Human Clinical Evidence

Nicotinamide mononucleotide (NMN) sits just one enzymatic step away from NAD+ in the biosynthesis pathway, making it an efficient precursor for NAD+ restoration. The human clinical evidence now spans multiple trials with consistent results.

Yoshino et al. (2021) conducted a landmark study published in Science.2 The researchers administered 250 mg of NMN daily to 25 prediabetic women for 10 weeks and documented a 25% improvement in muscle insulin sensitivity, comparable to the effects of 10% weight loss.

Yi et al. (2023) published a multi-dose trial in GeroScience examining 80 healthy middle-aged adults taking 300-900 mg of NMN daily for 60 days.3 The study demonstrated significant NAD+ increases at all dose levels (P≤0.001), improved walking distance, and stable biological age versus worsening in the placebo group.

Liao et al. (2021) in the Journal of the International Society of Sports Nutrition found dose-dependent improvements in aerobic capacity and ventilatory threshold in recreational runners.4

Igarashi et al. (2022) in NPJ Aging demonstrated improved gait speed in older men following NMN supplementation.5

Safety has been thoroughly established: Fukamizu et al. (2022) in Frontiers in Nutrition showed that 1,250 mg NMN daily for four weeks was safe and well-tolerated.6 Most clinical trials have used doses between 250–600 mg daily using tablet and capsule dosage forms.

TMG: Methylation Support

While NMN addresses NAD+ supply, trimethylglycine (TMG) supports the metabolic recycling that keeps NAD+ pathways functioning efficiently. When NAD+ is consumed by sirtuins, nicotinamide must be methylated for proper recycling and excretion. TMG provides methyl groups directly, supporting homocysteine metabolism and SAMe production.7 

Research shows TMG reduces homocysteine by up to 20% in a dose-dependent fashion.8 The theoretical basis for combining NMN and TMG rests on solid biochemical reasoning: high-dose NAD+ precursor supplementation may increase demand on methylation pathways, potentially depleting methyl donors over time. TMG provides three methyl groups directly to support this process.

It is important to note that no randomized controlled trial has directly tested the NMN plus TMG combination for synergistic effects. The recommendation is based on biochemical theory rather than direct clinical evidence of the combination.

NMN vs. NR: Understanding the Precursor Debate

Both NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are NAD+ precursors that effectively raise blood NAD+ levels in human trials. NR has a longer human research history spanning over six years, with well-established efficacy data. NMN sits one enzymatic step closer to NAD+ in the biosynthesis pathway and may achieve broader tissue distribution based on preclinical research.

Practically speaking, both precursors work. Choose based on product quality, dose adequacy, third-party testing, and formulation rather than getting caught up in precursor debates. Some formulations combine both for potential complementary benefits.

How Oral Film Strips (OFSs) enable rapid onset and enhanced absorption 

Research indicates that tablet and capsule dosage forms of NMN undergoes rapid hepatic conversion to nicotinamide, limiting how much intact NMN reaches peripheral tissues. Sublingual delivery enables compounds to absorb directly through the thin, highly vascularized tissue beneath the tongue, bypassing the stomach, intestine, and liver entirely.

Oral Film Strips (OFSs) have emerged as a modern drug-delivery platform offering distinct biopharmaceutical advantages over conventional tablets. Their ultra-thin polymeric matrices rapidly disintegrate upon contact with saliva, enabling immediate drug release and exposure to the highly vascularised buccal and sublingual mucosa, which supports rapid absorption and the potential avoidance of first-pass metabolism.9,10 

Numerous reviews highlight that this pre-gastric uptake can enhance systemic bioavailability, particularly for drugs with poor solubility, extensive first-pass metabolism, or slow disintegration from tablets.11,12 

OFSs also allow incorporation of permeation enhancers, solubilising agents, and mucoadhesive polymers, which increase mucosal residence time and improve transmucosal flux, further supporting superior absorption profiles compared with traditional solid oral dosage forms.13,14,15

Collectively, the literature positions OFSs as an innovative and patient-centric dosage form capable of delivering faster onset, improved absorption efficiency, and potentially higher effective bioavailability relative to standard tablets.16

Practical Considerations

The NMN oral film strip aligns with daily supplementation, consistent with clinical trials demonstrating benefits over weeks to months of continuous use. Blood NAD+ levels begin rising within hours of taking precursors, with measurable increases typically documented within two to four weeks. Functional benefits like improved insulin sensitivity and enhanced exercise capacity were observed after six to twelve weeks of consistent supplementation.

Consistent daily use matters, as NAD+ levels return to baseline after discontinuation. Individual response varies based on age, baseline NAD+ status, and overall health.

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease. Consult a healthcare provider before beginning any supplement regimen.

Frequently Asked Questions

What is a NAD supplement and how does it work?

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every cell, essential for over 500 enzymatic reactions including energy production, DNA repair, and sirtuin activation. NAD+ levels decline approximately 50% by middle age, impairing mitochondrial function and cellular repair capacity. NAD supplements provide precursors like NMN or NR that your body converts into NAD+. Human trials consistently show oral NMN raises blood NAD+ levels within weeks, supporting cellular energy and repair processes.3

What is the best NAD supplement to take?

The best NAD supplement combines several key features: adequate dosing (250-600 mg NMN daily), third-party testing verification, and enhanced bioavailability through optimized delivery. Sublingual formats like oral strips may improve absorption by bypassing liver metabolism. Consider formulations including TMG for methylation support. Focus on product quality and transparent testing rather than debating NMN versus NR precursors. Look for certificates of analysis and avoid products making disease treatment claims.

Do NAD supplements work?

Human clinical trials consistently demonstrate that NAD+ precursors raise blood NAD+ levels. Specific benefits documented include 25% improved insulin sensitivity (Yoshino et al., 2021)2, enhanced aerobic capacity in runners,4 and improved gait speed in older adults.5 The safety profile is well-established at typical supplement doses. However, while NAD+ elevation is proven, whether this translates to slowed aging in humans remains under investigation. Individual responses vary, with some people reporting subjective energy improvements.

What is the connection between NAD+ and TMG?

When NAD+ is consumed by sirtuins and other enzymes, nicotinamide is released as a byproduct that must be methylated for proper recycling and excretion. High-dose NAD+ precursor supplementation may theoretically increase demand on methylation pathways, potentially depleting methyl donors over time. TMG (trimethylglycine) provides three methyl groups directly, supporting this methylation process while also helping reduce homocysteine, a cardiovascular risk marker. The typical recommendation is a 1:1 ratio of TMG to NMN.*

How long does it take for NAD supplements to work?

Blood NAD+ levels begin rising within hours of taking precursors. Measurable increases are typically documented within two to four weeks in clinical trials. Functional benefits like improved insulin sensitivity and enhanced exercise capacity were observed after six to twelve weeks of consistent supplementation in research studies. Sublingual NAD+ showed a 59% blood level increase at week two in pilot research.17 Consistent daily use matters, as NAD+ levels return to baseline after discontinuation. Individual response varies based on age, baseline NAD+ status, and overall health.

What's the difference between NMN and NR supplements?

Both NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are NAD+ precursors that effectively raise blood NAD+ levels in human trials. NR has a longer human research history spanning over six years, with well-established efficacy data. NMN sits one enzymatic step closer to NAD+ in the biosynthesis pathway and may achieve broader tissue distribution based on preclinical research. Practically speaking, both precursors work. Choose based on product quality, dose adequacy, third-party testing, and formulation rather than getting caught up in precursor debates

* This rationale is based on biochemical theory; no randomized controlled trial has directly tested the NMN plus TMG combination for synergistic effects.

References

1. Camacho-Pereira, J., et al. (2016). CD38 dictates age-related NAD decline and mitochondrial dysfunction through an SIRT3-dependent mechanism. Cell Metabolism, 23(6), 1127-1139. https://doi.org/10.1016/j.cmet.2016.05.006

2. Yoshino, M., et al. (2021). Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science, 372(6547), 1224-1229. https://doi.org/10.1126/science.abe9985

3. Yi, L., et al. (2023). The efficacy and safety of beta-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults. GeroScience, 45(1), 29-43. https://doi.org/10.1007/s11357-022-00705-1

4. Liao, B., et al. (2021). Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: A randomized, double-blind study. Journal of the International Society of Sports Nutrition, 18(1), 54. https://doi.org/10.1186/s12970-021-00442-4

5. Igarashi, M., et al. (2022). Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men. NPJ Aging, 8(1), 5. https://doi.org/10.1038/s41514-022-00084-z

6. Fukamizu, Y., et al. (2022). Safety evaluation of beta-nicotinamide mononucleotide oral administration in healthy adult men and women. Frontiers in Nutrition, 9, 868640. https://doi.org/10.3389/fnut.2022.868640

7. Craig, S. A. (2004). Betaine in human nutrition. American Journal of Clinical Nutrition, 80(3), 539-549. https://doi.org/10.1093/ajcn/80.3.539

8. Olthof, M. R., et al. (2003). Low dose betaine supplementation leads to immediate and long term lowering of plasma homocysteine in healthy men and women. Journal of Nutrition, 133(12), 4135-4138. https://doi.org/10.1093/jn/133.12.4135

9. Patil, P., & Shrivastava, S. K. (2014). Fast dissolving oral films: An innovative drug delivery system. International Journal of Science and Research, 3(7), 2088–2093. [

10. Özakar, R. S., & Özakar, E. (2021). A current overview of oral thin films. Turkish Journal of Pharmaceutical Sciences, 18(1), 111–121.  

11. Paul, D., & Ray, P. (2023). Exploring the potential of fast dissolving oral films. Current Trends in Pharmaceutical Research, 10

12.  He, M., Zhu, L., Yang, N., Li, H., & Yang, Q. (2021). Recent advances of oral film as a platform for drug delivery. International Journal of Pharmaceutics, 604, Article 120759. https://doi.org/10.1016/j.ijpharm.2021.120759

13. Sharma, D., Kaur, D., Verma, S., Verma, S., Singh, M., & Garg, R. (2015). Fast dissolving oral films technology: A recent trend for an innovative oral drug delivery system. International Journal of Drug Delivery, 7(2), 

14. Bhaijamal, R. A., Virabhai, M. Y., Maisuriya, A. B., & Kachhiya, S. K. (2025). Comparative evaluation of fast dissolving films vs conventional oral dosage forms of antihistamine in terms of drug dissolution. International Journal of Innovative Research & Growth, 14(2), 14240–14258.  

15. Devaraj, H., Venkatachalam, S., & Radhakrishnan, A. (2018). A review on formulation of oral dissolving film. Journal of Chemical and Pharmaceutical Research, 10(4), 151–159. 

16. Dhankar, K., Tamrakar, H. K., Deshmukh, S., Wadhwa, G. S., Toppo, M. A., Jaya Shree, & Choudhary, R. (2025). Oral fast dissolving film: Pharmaceutical development and approaches. International Journal of Pharmaceutical Research and Development, 7(2), 04–12. https://doi.org/10.33545/26646862.2025.v7.i2a.157

17. iX Biopharma Ltd & NAD Laboratory Ltd. (2024). Breakthrough Sublingual Wafers Raise NAD⁺ Levels by 76% and Enhance Well-Being in Human Trial. Open-label pilot study in nine healthy adults.