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For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement.
AMIRAVOResearch Library

L-Glutathione vs NAD+

L-glutathione and NAD+ are both molecules the body makes itself, and both are marketed in wellness settings as infusions, which is where most of the interest in comparing them comes from 1,6. Glutathione is a tripeptide of glutamate, cysteine and glycine and the body's most abundant endogenous antioxidant; it has been tested in randomised trials in skin pigmentation, Parkinson's disease and cystic fibrosis 1,2,4,5. NAD+ is a coenzyme in energy metabolism and DNA repair, and a 2026 systematic review found no outcome trials of giving NAD+ itself by vein or muscle 6,7. The FDA lists both among bulk substances under evaluation for compounding, and neither is approved as a systemic drug 10,11.

Unbranded reference vial illustrating L-Glutathione; not an actual product
L-Glutathione
Not approved — research use only
Unbranded reference vial illustrating NAD+; not an actual product
NAD+
Not approved — research use only

Side by side

FieldL-GlutathioneNAD+
ClassEndogenous tripeptide (glutamate-cysteine-glycine) 1Endogenous coenzyme (a dinucleotide), not a peptide 6
Origin and structureMade mainly in the liver; described as the body's most abundant endogenous antioxidant 1,9Made in the body from dietary precursors; precursors such as nicotinamide riboside and nicotinamide mononucleotide are also studied 7
Proposed mechanismAntioxidant and detoxification roles; in skin research, inhibition of melanin production 1,9Coenzyme in cellular metabolism, mitochondrial function, DNA repair and stress-response signalling 6
Half-lifeNot located in the sources reviewed; in a 6-month oral trial, blood levels returned to baseline after a 1-month washout 1No half-life located; in a small human pilot, infused NAD+ was cleared from plasma with no measurable rise for the first 2 hours 8
Highest human trial phaseRandomised placebo-controlled trials, including a 153-participant inhaled trial in cystic fibrosis and a 60-participant oral skin trial 4,5Randomised trials of oral precursors; no outcome trials of intravenous or intramuscular NAD+ itself identified 7
FDA statusNot approved as a systemic drug; Drugs@FDA lists glutathione disulfide only as one of eight components of an ophthalmic irrigating solution (NDA 018469), queried 24 October 2026 12; 'Glutathione' is in 503A category 1 (under evaluation) as updated 14 May 2026 11Not FDA-approved; no Drugs@FDA record (queried 24 October 2026) 12; NAD is in 503A category 1 (under evaluation) as updated 14 May 2026 11
Published human outcomesOral supplementation raised blood and tissue glutathione over 6 months 1; a Parkinson's pilot found no significant difference in rating-scale change 2; an inhaled cystic fibrosis trial missed its primary lung-function endpoints 5Oral precursors consistently raise NAD-related blood markers, while functional and metabolic outcomes are heterogeneous and often null 7
Safety signalsAdverse events were similar to placebo in the Parkinson's pilot and the cystic fibrosis trial 2,5; a 2025 dermatology review states intravenous use is contraindicated, citing lack of efficacy and side effects 3Reported effects of intravenous NAD+ include nausea, cramping, flushing and chest discomfort; long-term safety data are lacking 6
WADA statusNot named on the 2026 Prohibited List 13Not named on the 2026 Prohibited List 13
Who funded the evidenceAcademic centres in the United States, Thailand, India and Germany; funding statements were not located for all trials 1,4,5Mixed academic and commercial authorship; one 2026 review author was employed by a healthcare company 6,7

L-Glutathione: what the data says

Glutathione is a tripeptide made mainly in the liver and described as the body's most abundant endogenous antioxidant 1,9. In a 6-month randomised, double-blind, placebo-controlled trial in 54 non-smoking adults, oral glutathione raised levels in blood, red cells, plasma, lymphocytes and buccal cells, with values returning to baseline after a 1-month washout 1.

Clinical results by condition are mixed. In a randomised, double-blind pilot in 21 people with Parkinson's disease, intravenous glutathione produced no significant difference in Unified Parkinson's Disease Rating Scale change versus placebo, and adverse events were similar between groups 2. In a randomised trial of inhaled glutathione in 153 people with cystic fibrosis, the primary lung-function endpoints did not differ from placebo 5. In a randomised, double-blind trial in 60 medical students, oral glutathione lowered melanin indices at two of six measured skin sites versus placebo 4. A 2025 systematic review of skin-lightening use concluded that topical and oral forms give moderate, unsustained effects and that the intravenous route is contraindicated for this purpose 3.

NAD+: what the data says

NAD+ is a coenzyme involved in cellular metabolism, mitochondrial function, DNA repair and stress-response signalling 6. A 2026 systematic review of 113 studies (33 human, 80 rodent) found that in rodents (animal data) raising NAD+ was often associated with metabolic and functional changes, while in humans oral nicotinamide riboside and nicotinamide mononucleotide consistently raised NAD-related blood markers but had heterogeneous and often null effects on functional and metabolic outcomes 7.

For NAD+ given directly by vein, that review found no eligible outcome trials 7. A pilot study in a small human cohort found that infused NAD+ was rapidly removed from plasma, with no rise in plasma NAD+ or its metabolites for the first 2 hours 8. A 2026 narrative review describes the human evidence for intravenous NAD+ as sparse, mainly small uncontrolled studies and case reports, and notes that whole-blood NAD+ concentrations do not appear to fall with healthy ageing on its own 6.

Key research differences

  • Chemistry: glutathione is a three-amino-acid peptide 1, whereas NAD+ is a dinucleotide coenzyme 6.
  • Trial evidence: glutathione has randomised placebo-controlled trials by oral, inhaled and intravenous routes 2,4,5; for NAD+ the randomised evidence concerns oral precursors, not NAD+ itself 7.
  • Intravenous use: a 2025 dermatology review calls intravenous glutathione contraindicated for skin lightening 3, while intravenous NAD+ has no outcome trials at all 7.
  • Body stores: oral glutathione raised measured tissue levels over 6 months 1; for NAD+, oral precursors raise blood markers while infused NAD+ was cleared rapidly in a pilot study 7,8.
  • Role in the cell: glutathione is described as an antioxidant and detoxification molecule 9, whereas NAD+ is a metabolic coenzyme 6.

Where the evidence is limited

No study has compared glutathione with NAD+. Their trials address unrelated conditions, from Parkinson's disease and cystic fibrosis to skin pigmentation for glutathione 2,4,5, and ageing or metabolic markers for NAD+ precursors 7. Routes differ too: much of the glutathione evidence is oral or inhaled, and much of the NAD+ evidence uses precursors rather than NAD+ 1,5,7. Raising a blood or tissue level is not the same as changing a clinical outcome, a gap both literatures share 1,7.

Frequently asked questions

Are glutathione and NAD+ both made by the body?
Yes. Glutathione is a tripeptide produced mainly in the liver 1,9, and NAD+ is a coenzyme the body makes from dietary precursors 6,7.
Does giving them by vein have trial support?
For glutathione, a Parkinson's pilot found no significant difference versus placebo 2, and a 2025 review calls the intravenous route contraindicated for skin lightening 3. For NAD+, a 2026 systematic review found no outcome trials of intravenous administration 7.
Can glutathione and NAD+ be compared directly?
Not on current evidence. They are different molecules studied in different conditions and by different routes, with no head-to-head trial 5,7.
Are either FDA-approved?
Neither is approved for systemic use. Both appear in 503A category 1, bulk substances under evaluation for compounding, as of 14 May 2026 11,12.

References

  1. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione European Journal of Nutrition. 2015
  2. Randomized, double-blind, pilot evaluation of intravenous glutathione in Parkinson's disease Movement Disorders. 2009
  3. Glutathione as a skin-lightening agent and in melasma: a systematic review International Journal of Dermatology. 2025
  4. Glutathione as an oral whitening agent: a randomized, double-blind, placebo-controlled study Journal of Dermatological Treatment. 2012
  5. Inhalation treatment with glutathione in patients with cystic fibrosis: a randomized clinical trial American Journal of Respiratory and Critical Care Medicine. 2013
  6. Narrative review of intravenous NAD+ and NAD+ precursors in wellness and translational medicine Frontiers in Aging. 2026
  7. NAD+ supplementation for anti-aging and wellness: A PRISMA-guided systematic review of preclinical and clinical evidence Ageing Research Reviews. 2026
  8. A Pilot Study Investigating Changes in the Human Plasma and Urine NAD+ Metabolome During a 6 Hour Intravenous Infusion of NAD Frontiers in Aging Neuroscience. 2019
  9. A review of the potential benefits and limitations of oral glutathione supplementation Inflammopharmacology. 2026
  10. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (content current as of 04/22/2026) FDA (Human Drug Compounding). 2026
  11. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act (updated May 14, 2026) FDA. 2026
  12. Drugs@FDA via openFDA: queries for glutathione (NDA 018469 BSS PLUS, glutathione disulfide as one of eight components; NDA 020079 discontinued) and nicotinamide adenine dinucleotide (no match), queried 24 October 2026 openFDA. 2026
  13. Prohibited List (2026 List, in force 1 January 2026) World Anti-Doping Agency. 2026

For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement. This page compares published research and is not medical advice or a recommendation.