Glutathione: Benefits, Forms, Dosing, and Side Effects

Table of Contents

• Overview
• Forms and Bioavailability
• Evidence for Benefits
• Recommended Dosing
• Safety and Side Effects
• Drug Interactions
• Dietary Sources
• References

Overview

Glutathione (GSH) is a tripeptide composed of three amino acids — cysteine, glutamic acid, and glycine — and is the most abundant intracellular antioxidant in the human body [1][2]. It exists in virtually every cell, with the highest concentrations found in the liver (up to 10 mM), where it plays a central role in detoxification, and in the lungs, kidneys, and brain [2][3]. Glutathione functions through two primary mechanisms: direct scavenging of reactive oxygen species (ROS) and serving as a cofactor for glutathione peroxidase, a family of enzymes that neutralize hydrogen peroxide and lipid peroxides [2][4].

Glutathione exists in two forms: the reduced form (GSH), which is the active antioxidant, and the oxidized form (GSSG, glutathione disulfide), which is produced when GSH donates electrons to neutralize free radicals. The ratio of GSH to GSSG is a key indicator of cellular oxidative stress, with a healthy cell maintaining a ratio greater than 100:1 [2][5]. The enzyme glutathione reductase, which requires NADPH as a cofactor, recycles GSSG back to GSH, maintaining this ratio [2].

Beyond its antioxidant role, glutathione is involved in numerous critical physiological processes [2][3][4]:

• Phase II detoxification: Glutathione S-transferase enzymes conjugate glutathione to xenobiotics (drugs, pollutants, carcinogens), making them water-soluble for excretion. This is the primary pathway for detoxifying acetaminophen (paracetamol), heavy metals, and numerous environmental toxins [2][6].
• Immune function: Glutathione is essential for lymphocyte proliferation, natural killer (NK) cell activity, and optimal T-cell function. Intracellular GSH levels regulate the balance between Th1 and Th2 immune responses [7][8].
• Protein thiol homeostasis: Glutathione maintains proteins in their reduced (functional) state through S-glutathionylation, a reversible post-translational modification that regulates protein activity under oxidative stress [2].
• Amino acid transport: The gamma-glutamyl cycle uses glutathione to transport amino acids across cell membranes, a process essential for cellular amino acid uptake [2][3].
• Regulation of cell proliferation and apoptosis: Glutathione depletion is a signal for apoptosis (programmed cell death), while adequate levels support normal cell proliferation [2][5].

Glutathione synthesis occurs in two ATP-dependent steps catalyzed by the enzymes gamma-glutamylcysteine ligase (GCL, the rate-limiting step) and glutathione synthetase [2]. Cysteine availability is typically the rate-limiting factor for synthesis, which is why N-acetyl cysteine (NAC), a cysteine donor, is one of the most effective strategies for raising glutathione levels [2][9].

Glutathione levels decline with age. Cross-sectional studies have shown that plasma and tissue glutathione concentrations decrease by approximately 10-15% per decade after age 45, and this decline is accelerated in conditions associated with chronic oxidative stress, including type 2 diabetes, cardiovascular disease, neurodegenerative diseases, HIV/AIDS, chronic liver disease, and chronic obstructive pulmonary disease (COPD) [2][3][10][11]. Whether this decline is a cause or consequence of aging and disease remains an active area of research. Some investigators have proposed that glutathione depletion is a common mechanism underlying multiple age-related diseases, making it a therapeutic target for healthy aging [10][11].

It is not essential to obtain glutathione from the diet because the body synthesizes it endogenously. Dietary intake is modest — estimated at 100-150 mg/day from fruits, vegetables, and meats — and much of this is broken down by digestive enzymes (gamma-glutamyltranspeptidase and dipeptidases) in the intestinal lumen before absorption [1][2]. Similarly, oral glutathione supplements have historically been considered poorly bioavailable, though newer formulations (liposomal, sublingual, S-acetyl) aim to improve this [1][12].

Forms and Bioavailability

The central challenge of glutathione supplementation is bioavailability. Oral glutathione is subject to degradation by digestive enzymes, and early studies found that a single oral dose of up to 3,000 mg failed to increase plasma glutathione levels in healthy volunteers [1][13]. However, more recent evidence suggests that sustained supplementation at moderate doses may modestly raise levels over time.

Reduced L-Glutathione (GSH)

All glutathione in supplements is L-glutathione in the reduced form — the same active form used in the body. Labels that emphasize "reduced" or "L-" glutathione are redundant; the oxidized form (glutathione disulfide, GSSG) is not used in supplements [1]. A common branded form is Setria (by Kyowa Hakko), produced by fermentation without animal-origin materials.

Bioavailability data: A study by Witschi et al. (1992) found that a single oral dose of 3,000 mg glutathione did not significantly increase plasma glutathione in healthy volunteers, suggesting poor absorption from a single dose [13]. However, a 6-month RCT funded by Kyowa Hakko (n=54) found that taking 250 mg or 1,000 mg of Setria glutathione daily for 6 months significantly increased glutathione levels in blood, buccal cells, and erythrocytes, with the higher dose producing greater increases. Erythrocyte GSH increased by 30-35% at the 1,000 mg dose after 6 months (Richie et al., Eur J Nutr, 2015) [12]. Notably, levels returned to baseline after a 1-month washout period, indicating that continuous supplementation is required to maintain elevated levels. Shorter studies (single dose or 1 month) have generally shown little to no effect [1][12].

Mechanism of action when taken orally: Even though some oral glutathione is degraded in the gut, the resulting amino acids (cysteine, glycine, glutamate) serve as substrates for de novo glutathione synthesis in tissues. Additionally, intact glutathione may be absorbed via specific peptide transporters in the small intestine [12][14].

Liposomal Glutathione

Liposomal formulations encapsulate glutathione within phospholipid vesicles (typically derived from sunflower lecithin/phosphatidylcholine) to protect it from enzymatic degradation and enhance absorption across the intestinal mucosa.

Evidence: A small uncontrolled study (n=12) by Sinha et al. (Eur J Clin Nutr, 2018) found that liposomal glutathione at 500 mg or 1,000 mg daily for 1 month increased blood glutathione levels by 40% at the higher dose [15]. However, the study lacked a placebo control, and the increases were not dramatically better than those seen with regular (non-liposomal) glutathione at similar doses in the Richie et al. study [1][12]. A subsequent pilot study (n=12) comparing oral liposomal glutathione (500 mg twice daily for 2 weeks) found increases in GSH levels in whole blood, erythrocytes, and plasma, along with reductions in 8-isoprostane (a marker of oxidative stress) (Buonocore et al., Oxid Med Cell Longev, 2016) [16]. While promising, these studies are small and short-term.

Practical consideration: Liposomal formulations are typically more expensive. The evidence for clinically meaningful superiority over regular glutathione is not yet established [1].

S-Acetyl Glutathione (SAG)

S-acetyl glutathione is a derivative in which an acetyl group is attached to the sulfur atom of the cysteine residue, theoretically protecting it from oxidation and enzymatic degradation in the gut. Once absorbed, intracellular esterases remove the acetyl group to release free glutathione.

Evidence: A crossover study in healthy Italian volunteers compared a single high oral dose of SAG (3.5 g as powder dissolved in water) with the same dose of regular L-glutathione (3.5 g as capsules). While average plasma glutathione levels were slightly higher with SAG, erythrocyte glutathione levels were somewhat lower compared to regular glutathione (Cavallaro et al., Int J Clin Nutr Diet, 2018) [17]. Notably, one of the researchers was an employee of the SAG supplement manufacturer (Emothion, Gnosis S.p.A.) [1]. The evidence does not convincingly demonstrate superiority of SAG over standard glutathione.

N-Acetyl Cysteine (NAC)

NAC is not glutathione itself but is the most well-established precursor for raising intracellular glutathione levels. NAC provides cysteine — the rate-limiting amino acid for glutathione synthesis — in a stable, bioavailable form [9][18].

Bioavailability: NAC has an oral bioavailability of approximately 6-10% due to extensive first-pass metabolism, but the deacetylated cysteine that reaches tissues effectively drives glutathione synthesis [9]. NAC has been used clinically for decades as an FDA-approved drug for acetaminophen overdose (where it replenishes hepatic glutathione) and as a mucolytic agent [18].

Evidence for raising glutathione: Multiple studies have demonstrated that NAC supplementation (600-1,800 mg/day) increases intracellular glutathione levels in various tissues, including erythrocytes, lymphocytes, and lung epithelial cells [9][18][19]. A meta-analysis by Dodd et al. (Expert Opin Biol Ther, 2008) confirmed that NAC reliably increases peripheral blood glutathione markers across multiple populations [20].

Glycine + NAC (GlyNAC)

The combination of glycine and N-acetyl cysteine provides both rate-limiting substrates for glutathione synthesis (cysteine from NAC and glycine directly). This combination has gained significant research attention for aging-related glutathione deficiency.

Key evidence: A pilot RCT by Kumar et al. (Clin Transl Med, 2021) in 24 older adults (aged 61-80) found that supplementation with GlyNAC (glycine 100 mg/kg/day + NAC 100 mg/kg/day, approximately 7 g each for a 70 kg person) for 16 weeks corrected glutathione deficiency and improved multiple hallmarks of aging including oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, body composition, exercise capacity, and cognition [10]. A subsequent larger RCT (n=72) confirmed these findings, showing improvements in gait speed, grip strength, exercise capacity, waist circumference, and systolic blood pressure (Kumar et al., J Gerontol A Biol Sci Med Sci, 2023) [21].

Whey Protein

Whey protein is rich in cysteine and cystine (the oxidized dimer of cysteine) and has been shown to increase glutathione levels. The cysteine in whey protein is largely present as glutamylcystine, which is resistant to digestive degradation and serves as an efficient substrate for glutathione synthesis [22].

Evidence: A study in HIV-positive patients found that whey protein supplementation (45 g/day for 2 weeks) significantly increased plasma glutathione levels (Micke et al., Eur J Clin Invest, 2001) [22]. Several studies in athletes and elderly populations have also shown that whey protein supplementation increases blood glutathione markers [23].

Other Glutathione-Sparing Compounds

Several nutrients help maintain glutathione levels by reducing its consumption or supporting its recycling:

• Vitamin C (ascorbic acid): Spares glutathione by scavenging reactive oxygen species directly, reducing the demand for glutathione as an antioxidant. A study found that vitamin C supplementation (500-1,000 mg/day) increased lymphocyte glutathione by 18% (Lenton et al., Am J Clin Nutr, 2003) [24]. Dr Brad Stanfield's MicroVitamin includes 45 mg of vitamin C as calcium ascorbate, which may contribute to glutathione sparing alongside dietary intake.
• Alpha-lipoic acid (ALA): Both a direct antioxidant and a potent inducer of glutathione synthesis. ALA increases cysteine availability by reducing cystine to cysteine and upregulates the expression of gamma-glutamylcysteine ligase. Supplementation with 300-600 mg/day has been shown to increase intracellular glutathione levels by 30-70% in cell culture and animal studies, with more modest increases in human trials (Suh et al., Proc Natl Acad Sci, 2004) [25].
• Selenium: Required cofactor for glutathione peroxidase, the enzyme family that uses glutathione to neutralize peroxides. Selenium deficiency impairs the glutathione antioxidant system even when glutathione levels are adequate [26]. MicroVitamin provides 27.5 mcg of selenium as selenium glycinate, supporting glutathione peroxidase activity.
• Sulforaphane (from broccoli sprouts): A potent Nrf2 activator that upregulates genes involved in glutathione synthesis, including GCL. Sulforaphane supplementation has been shown to increase hepatic and blood glutathione levels in human studies (Fahey et al., Proc Natl Acad Sci, 1997; Riedl et al., Clin Immunol, 2009) [27][28].

Comparison Table

Form	Typical Dose	Bioavailability	Raises GSH Levels?	Cost	Notes
Reduced L-Glutathione	250-1,000 mg/day	Low (improves with sustained use)	Modestly, after 3-6 months [12]	Moderate	All supplement glutathione is this form. "Reduced" and "L-" on labels are redundant [1].
Liposomal Glutathione	250-1,000 mg/day	Potentially improved	Yes, comparable to regular GSH [15][16]	High	Phospholipid encapsulation may protect from digestive breakdown. Small studies only.
S-Acetyl Glutathione	200-600 mg/day	Uncertain	Mixed results [17]	High	Acetyl group may protect sulfhydryl group. Industry-funded evidence. Not convincingly superior.
NAC	600-1,800 mg/day	6-10% (cysteine delivery)	Reliably, via precursor pathway [9][18][20]	Low	Most evidence-backed approach. FDA-approved drug. Well-studied safety profile.
GlyNAC (Glycine + NAC)	~7 g each/day	Good (amino acid absorption)	Strongly, in older adults [10][21]	Low-Moderate	Provides both rate-limiting substrates. Promising aging research.
Whey Protein	20-45 g/day	High (protein absorption)	Modestly [22][23]	Low-Moderate	Food-based approach. Also provides complete protein.
Sublingual Glutathione	100-250 mg	Bypasses GI tract	Limited data	High	Theoretical advantage of buccal absorption. Minimal clinical evidence.
IV Glutathione	600-2,400 mg	100% (direct)	Yes, transiently	Very high	Used clinically (Parkinson's research). Rapid clearance. Not practical for daily use. Side effects reported.

How to Take Glutathione

Most products suggest taking glutathione on an empty stomach (with water only). This is because digestive enzymes, which are more active during meals, readily break down glutathione. Taking it between meals, when enzyme activity is diminished, may increase the chance of intact absorption [1]. However, some products recommend taking glutathione with a meal to reduce stomach upset. Mild GI discomfort (nausea, bloating) is occasionally reported, particularly at higher doses [1][29].

Evidence for Benefits

Aging and Oxidative Stress

Glutathione depletion is a consistent finding in aging research. Plasma and tissue GSH levels decline with age, while markers of oxidative damage increase, creating a "redox imbalance" implicated in the pathogenesis of age-related diseases [2][3][10][11].

GlyNAC in older adults: The most compelling evidence for glutathione supplementation in aging comes from the GlyNAC studies by Kumar et al. at Baylor College of Medicine. In an initial pilot RCT (n=24, aged 61-80), 16 weeks of GlyNAC supplementation (glycine + NAC, each at 100 mg/kg/day) corrected glutathione deficiency, reduced oxidative stress (measured by plasma TBARS and F2-isoprostanes), lowered inflammation (IL-6, TNF-alpha), improved mitochondrial function (assessed by muscle MRS), reduced insulin resistance (HOMA-IR), decreased genomic damage (8-OHdG), improved endothelial function, reduced body fat, increased exercise capacity (by 30%), and improved cognition (Kumar et al., Clin Transl Med, 2021) [10]. All improvements reversed after 12 weeks of stopping supplementation, suggesting ongoing use is required.

A larger follow-up RCT (n=72 older adults) confirmed these findings, additionally demonstrating improvements in gait speed (+0.14 m/s), grip strength, 6-minute walk distance, waist circumference reduction, and systolic blood pressure reduction (Kumar et al., J Gerontol A Biol Sci Med Sci, 2023) [21]. The same research group also published a study in older adults with HIV showing similar benefits, including reduced oxidative stress and improved mitochondrial fatty acid oxidation (Kumar et al., Antioxidants, 2020) [30].

Glutathione and hallmarks of aging: A study in older adults (n=48, aged 60-80) found that GlyNAC supplementation for 16 weeks improved several molecular hallmarks of aging, including mitophagy, nutrient sensing (reduced mTOR activation, increased AMPK signaling), inflammation (reduced NF-kB activation), and genomic instability (reduced 8-OHdG), alongside increased telomerase activity (Kumar et al., Aging, 2023) [31].

Caloric restriction mimicry: Some investigators have noted that the metabolic effects of glutathione repletion in older adults — improved insulin sensitivity, reduced inflammation, enhanced mitochondrial function — overlap substantially with known benefits of caloric restriction, suggesting that glutathione deficiency may partly mediate the metabolic decline of aging [10][11].

Liver Health and Detoxification

The liver contains the highest glutathione concentration of any organ, with levels reaching 5-10 mM [2][6]. Hepatic glutathione is essential for Phase II conjugation reactions that detoxify drugs, environmental pollutants, heavy metals, and endogenous waste products [6].

Acetaminophen toxicity: The most well-established clinical application of glutathione repletion is the treatment of acetaminophen (paracetamol) overdose. Acetaminophen's toxic metabolite NAPQI depletes hepatic glutathione; when glutathione falls below approximately 30% of normal, NAPQI covalently binds hepatocyte proteins, causing necrosis. Intravenous NAC is the standard of care, providing cysteine to regenerate glutathione (Smilkstein et al., N Engl J Med, 1988) [32]. This is FDA-approved and one of the clearest demonstrations that glutathione repletion has a life-saving clinical role.

Non-alcoholic fatty liver disease (NAFLD): Oxidative stress and glutathione depletion are characteristic findings in NAFLD and its more severe form, non-alcoholic steatohepatitis (NASH). An RCT in 72 patients with NAFLD found that NAC (600 mg twice daily) for 3 months significantly improved liver enzymes (ALT, AST) and markers of oxidative stress compared to control, though it did not significantly improve liver histology on biopsy (Khoshbaten et al., Hepat Mon, 2010) [33].

Alcoholic liver disease: Chronic alcohol consumption severely depletes hepatic glutathione through multiple mechanisms: increased ROS production during ethanol metabolism, reduced cysteine availability, and impaired mitochondrial glutathione transport. Glutathione depletion renders hepatocytes vulnerable to TNF-alpha-induced apoptosis, contributing to alcoholic hepatitis [6][35]. NAC has shown benefit as adjunctive therapy in some trials. An RCT of 174 patients with severe alcoholic hepatitis found that the combination of prednisolone + NAC (IV for 5 days, then oral for 2 weeks) significantly reduced 1-month mortality compared to prednisolone alone (8% vs 24%, p=0.006), though the difference was not significant at 6 months (Nguyen-Khac et al., N Engl J Med, 2011) [36].

Heavy metal detoxification: Glutathione conjugation is a primary pathway for detoxifying mercury, arsenic, cadmium, and lead. Glutathione binds to these metals via its sulfhydryl group, forming conjugates that are excreted in bile and urine [2][6]. NAC supplementation has been studied for heavy metal detoxification, with some evidence of benefit for mercury and lead excretion, though clinical trials are limited [37].

Immune Function

Glutathione is critical for immune cell function. Intracellular GSH levels regulate lymphocyte proliferation, T-cell activation, NK cell cytotoxicity, and macrophage function [7][8].

HIV/AIDS: Glutathione deficiency is a hallmark of HIV infection and correlates with disease progression and mortality. Multiple studies have shown that NAC supplementation (600-8,000 mg/day) can increase CD4+ T-cell counts, reduce viral load markers, and improve survival in HIV-positive individuals (Herzenberg et al., Proc Natl Acad Sci, 1997) [38]. A landmark observational study found that glutathione deficiency (measured as low cysteine levels) was an independent predictor of 2-year survival in HIV patients [38]. NAC supplementation has been shown to improve lymphocyte glutathione levels and immune markers in HIV-positive subjects (De Rosa et al., Eur J Clin Invest, 2000) [39].

Respiratory infections: Glutathione plays a protective role in the lung epithelium, which is exposed to high levels of oxidative stress from inhaled pollutants and pathogens. A notable double-blind RCT in 262 elderly subjects found that NAC (600 mg twice daily) for 6 months significantly reduced influenza-like episodes — only 25% of NAC-treated subjects who seroconverted to influenza A developed clinical symptoms, compared to 79% of placebo subjects (De Flora et al., Eur Respir J, 1997) [40].

Sepsis: A small RCT in patients with sepsis found that IV NAC (150 mg/kg bolus then 50 mg/kg over 4 hours) improved hepatosplanchnic perfusion, glutathione levels, and liver function markers. However, larger trials have not consistently shown mortality benefit (Rank et al., Crit Care Med, 2000) [41].

Autoimmune disease: Glutathione redox status modulates the Th1/Th2 balance of immune responses. This has led to interest in NAC for conditions like systemic lupus erythematosus (SLE), where a small RCT found that NAC (2.4-4.8 g/day) improved disease activity scores and reduced anti-dsDNA antibody levels (Lai et al., Lupus, 2012) [42].

Respiratory and Lung Health

COPD: Chronic obstructive pulmonary disease is characterized by chronic oxidative stress and glutathione depletion in the lungs. A Cochrane systematic review of NAC for COPD exacerbations (39 RCTs, n=7,436) found that NAC and other mucolytics significantly reduced the frequency of acute exacerbations (OR 0.75, 95% CI 0.62-0.92) (Poole et al., Cochrane Database Syst Rev, 2019) [43].

The landmark PANTHEON trial, a 1-year multicenter RCT in 1,006 Chinese COPD patients, found that high-dose NAC (600 mg twice daily) reduced the rate of acute exacerbations by 22% compared to placebo (1.16 vs 1.49 exacerbations per year, p=0.0011) (Zheng et al., Lancet Respir Med, 2014) [44].

Idiopathic pulmonary fibrosis (IPF): NAC was studied in the PANTHER-IPF trial, a large multicenter RCT. The triple therapy arm (prednisone + azathioprine + NAC 600 mg three times daily) was stopped early due to increased harm. However, the NAC monotherapy arm (600 mg three times daily) showed a trend toward slower decline in forced vital capacity (FVC) that did not reach statistical significance compared to placebo (Martinez et al., N Engl J Med, 2014) [45]. A subsequent analysis suggested that NAC may benefit a subgroup of IPF patients with the TOLLIP rs3750920 TT genotype (Oldham et al., Am J Respir Crit Care Med, 2015) [46].

Cystic fibrosis: Inhaled glutathione and oral NAC have been studied in cystic fibrosis, where lung glutathione is severely depleted. A small RCT (n=21) found that inhaled glutathione (600 mg twice daily for 3 months) modestly improved some pulmonary function parameters (Griese et al., Am J Respir Crit Care Med, 2004) [47].

Cognitive Function and Neurodegenerative Disease

Glutathione is found in significant concentrations in the brain, where it scavenges free radicals that contribute to neuronal damage. The brain is particularly vulnerable to oxidative stress due to its high oxygen consumption, abundant polyunsaturated fatty acids, and relatively modest antioxidant defenses compared to other organs [1][2][48].

Alzheimer's disease: Lower glutathione levels in the brain have been measured in people with Alzheimer's disease using magnetic resonance spectroscopy (MRS), and the degree of depletion correlates with greater decline in cognitive function (Mandal et al., Biol Psychiatry, 2015) [48]. However, there do not appear to be any completed clinical trials assessing direct glutathione supplementation for Alzheimer's disease [1]. The GlyNAC combination provides the most relevant evidence — in the Kumar et al. (2021) pilot RCT, older adults receiving GlyNAC for 16 weeks showed significant improvements in cognitive testing, including the Montreal Cognitive Assessment (MoCA) and Digit Symbol Substitution Test [10].

Parkinson's disease: Glutathione depletion in the substantia nigra is one of the earliest biochemical changes in Parkinson's disease, occurring before dopaminergic neuron loss becomes apparent [49]. A pilot open-label study by Sechi et al. (Prog Neuropsychopharmacol Biol Psychiatry, 1996) found that IV glutathione (600 mg twice daily for 30 days) improved motor symptoms by 42% on the UPDRS, with benefits lasting 2-4 months [50]. However, a subsequent randomized placebo-controlled trial by Hauser et al. (Mov Disord, 2009) found no significant benefit of IV glutathione (1,400 mg three times weekly for 4 weeks) over placebo [51]. A larger phase IIb trial of intranasal glutathione (300 mg/dose, three times daily for 3 months, n=45) also showed no significant improvement over placebo (Mischley et al., J Parkinsons Dis, 2017) [52].

NAC has shown more promise. An open-label study (n=42) found that IV NAC (50 mg/kg) combined with oral NAC (500 mg twice daily) for 3 months increased brain glutathione levels (measured by MRS), increased dopamine transporter binding (measured by DaTscan), and improved UPDRS motor scores (Monti et al., PLoS One, 2016) [53]. This study lacked a placebo control, so results should be interpreted cautiously.

Type 2 Diabetes and Metabolic Health

Glutathione deficiency is commonly observed in type 2 diabetes, driven by hyperglycemia-induced oxidative stress, impaired cysteine availability, and reduced activity of glutathione synthesis enzymes [2][11].

Direct glutathione supplementation: An RCT in India randomized 206 people with type 2 diabetes (aged 31-78, HbA1c 7.1-9.7%) to receive either 500 mg glutathione daily alongside antidiabetic medications for 6 months, or antidiabetic medications alone. Glutathione levels increased in the supplement group, but there was no overall improvement in diabetes markers. Only a subset of participants aged 55 and older showed a modest benefit — approximately a 1 percentage point reduction in HbA1c (from 8.6% to 7.7%) and a slight increase in fasting insulin. However, the study lacked a placebo control, limiting interpretation (Kalamkar et al., Antioxidants, 2022) [55].

NAC and metabolic parameters: NAC has been more extensively studied for metabolic health. An RCT in 36 patients with type 2 diabetes found that NAC (1,200 mg/day for 4 weeks) combined with a standard diabetes diet significantly reduced fasting glucose, HbA1c, and markers of oxidative stress compared to diet alone (Shahidi et al., J Diabetes Metab Disord, 2020) [56]. A meta-analysis of 8 RCTs found that NAC supplementation significantly reduced fasting glucose (WMD: -5.84 mg/dL) and HbA1c (WMD: -0.27%) in people with metabolic conditions (Sarkaki et al., Clin Nutr ESPEN, 2021) [57].

GlyNAC and insulin resistance: In the Kumar et al. (2021) pilot RCT, GlyNAC supplementation in older adults reduced HOMA-IR (a marker of insulin resistance) to levels comparable to younger controls [10]. This was confirmed in their larger follow-up trial [21].

Polycystic ovary syndrome (PCOS): NAC has been studied as an adjunct to clomiphene for ovulation induction in PCOS. An RCT (n=150) found that NAC (1,200 mg/day) plus clomiphene significantly improved ovulation rate and pregnancy rate compared to clomiphene plus placebo (Rizk et al., Fertil Steril, 2005) [58]. A systematic review confirmed that NAC improves ovulation rate and hormonal parameters in PCOS (Thakker et al., Obstet Gynecol Int, 2015) [59].

Skin Health and Lightening

Glutathione has gained popularity as an oral and injectable skin-lightening agent, particularly in parts of Asia.

Mechanism: Glutathione inhibits tyrosinase, a key enzyme in melanin production, and promotes the synthesis of pheomelanin (a red/yellow pigment) over eumelanin (a black/brown pigment). People with more pheomelanin tend to have lighter skin. Observational data shows lower levels of reduced glutathione in darker skin compared to lighter skin [1][60].

Oral supplementation: Preliminary studies in Thai and Filipino individuals with tan skin have suggested that 500 mg of glutathione daily for 4-8 weeks may modestly lighten skin based on reduced melanin content. A randomized, double-blind, placebo-controlled trial in 60 Thai medical students found that glutathione (500 mg/day for 4 weeks) reduced melanin index scores at multiple body sites compared to placebo (Arjinpathana & Asawanonda, J Dermatolog Treat, 2012) [61]. However, results are limited by the small size, short duration, and lack of long-term follow-up [1][60].

Negative evidence: A study in Indonesian individuals showed that supplementation with glutathione combined with vitamin C, alpha-lipoic acid, and zinc did not significantly lighten skin compared to placebo (Sitohang et al., J Clin Aesthet Dermatol, 2021) [63]. Furthermore, intravenous glutathione (12 injections of 1,200 mg) showed no benefit for skin lightening compared to placebo in a Pakistani study (Zubair et al., J Pakistan Assoc Dermatol, 2016) [64].

Safety concerns with IV glutathione for skin lightening: Side effects including skin rashes, abdominal pain, thyroid dysfunction, liver dysfunction, kidney dysfunction, and possible kidney failure have been reported with intravenous glutathione injections [60]. The Philippine FDA, the Philippine Dermatological Society, and the Dermatological Society of Singapore have issued advisories against using IV glutathione for skin lightening [60].

Cardiovascular Health

Oxidative stress and endothelial dysfunction are central to atherogenesis and cardiovascular disease. Glutathione plays a protective role in maintaining endothelial function, preventing LDL oxidation, and modulating inflammatory signaling in the vascular wall [2][5].

Endothelial function: The GlyNAC studies by Kumar et al. demonstrated improvements in endothelial function markers in older adults following glutathione repletion [10][21]. NAC supplementation (600 mg/day) has been shown to improve flow-mediated dilation in patients with chronic heart failure in a small RCT (Andrews et al., J Am Coll Cardiol, 2001) [65].

Homocysteine reduction: NAC has been shown to lower plasma homocysteine levels by 11.5% at a dose of 1,800 mg/day in patients with hyperhomocysteinemia, likely through a disulfide exchange reaction (Ventura et al., Pharmacology, 2003) [66].

Contrast-induced nephropathy prevention: Multiple RCTs have studied NAC for prevention of contrast-induced kidney injury during coronary angiography. A meta-analysis of 26 RCTs (n=3,864) found that NAC (typically 600 mg twice daily) reduced the incidence of contrast-induced nephropathy by 40% (OR 0.60, 95% CI 0.44-0.81) (Gonzales et al., BMC Med, 2007) [67]. However, the larger ACT trial (n=2,308) did not confirm this benefit (ACT Investigators, Circulation, 2011) [68]. The evidence remains controversial.

Fertility

Male fertility: Oxidative stress is a major contributor to male infertility, damaging sperm DNA, membranes, and motility. An RCT in 50 infertile men found that NAC (600 mg/day for 3 months) significantly improved sperm concentration, motility, and morphology and reduced oxidative stress markers (Ciftci et al., Urology, 2009) [69]. A Cochrane review of antioxidant supplementation for male infertility found that NAC was among the most effective agents for improving sperm parameters (Smits et al., Cochrane Database Syst Rev, 2019) [70].

Female fertility (IVF): NAC has been studied as an adjunct during IVF cycles. A study found that adding NAC (1,200 mg/day) to the stimulation protocol improved follicle number and oocyte quality in women with poor ovarian response (Cheraghi et al., Cell J, 2019) [71].

Psychiatric Conditions

NAC has been extensively studied for psychiatric conditions, primarily through its role in modulating glutathione-dependent redox signaling and glutamate neurotransmission.

Obsessive-compulsive disorder (OCD): An RCT in 48 patients found that NAC (2,400 mg/day) as an add-on to fluvoxamine significantly improved Yale-Brown OCD Scale scores compared to placebo over 12 weeks (Afshar et al., J Clin Psychopharmacol, 2012) [72].

Depression: A meta-analysis of 5 RCTs (n=574) found that NAC significantly improved depressive symptoms, particularly in individuals with high baseline symptom severity (Fernandes et al., J Clin Psychiatry, 2016) [73]. The mechanism likely involves correction of oxidative stress and modulation of glutamate signaling via the cystine-glutamate antiporter (system Xc-) [73][74].

Bipolar disorder: A landmark RCT (n=75) found that NAC (1,000 mg twice daily for 24 weeks) produced a significant improvement in depression scores (Montgomery-Asberg Depression Rating Scale) in bipolar disorder as an adjunct to usual treatment (Berk et al., Biol Psychiatry, 2008) [74].

Schizophrenia: A meta-analysis of NAC augmentation in schizophrenia found significant improvements in total PANSS scores and negative symptoms (Yolland et al., Aust N Z J Psychiatry, 2020) [75].

Substance use disorders: NAC has shown promise for reducing cravings in cannabis, cocaine, and nicotine dependence. A pivotal RCT in 116 cannabis-dependent adolescents found that NAC (1,200 mg twice daily) more than doubled the odds of a negative urine cannabinoid test compared to placebo (OR 2.4, 95% CI 1.1-5.2) (Gray et al., Am J Psychiatry, 2012) [76].

Cancer

The relationship between glutathione and cancer is complex and paradoxical. Glutathione deficiency may promote cancer initiation (by failing to protect DNA from oxidative damage), while elevated glutathione in established tumors may promote cancer progression and treatment resistance (by protecting cancer cells from chemotherapy and radiation) [2][5].

Chemotherapy side effects: NAC has been studied for reducing chemotherapy-induced toxicity. An RCT in patients receiving cisplatin chemotherapy found that NAC (1,200 mg/day) significantly reduced nephrotoxicity and ototoxicity without reducing antitumor efficacy (Riga et al., Am J Clin Oncol, 2013) [77].

Important caution: Given the dual role of glutathione in cancer biology, glutathione or NAC supplementation should NOT be taken during active cancer treatment without oncologist approval, as it could theoretically protect tumor cells from therapy [2][5].

Recommended Dosing

Direct Glutathione Supplementation

There is no established Recommended Dietary Allowance (RDA) for glutathione because it is not an essential nutrient — the body synthesizes it endogenously.

Oral reduced glutathione: 250-1,000 mg/day based on the Richie et al. (2015) study. Higher doses (1,000 mg/day) were more effective at raising blood glutathione levels. Effects require 3-6 months of continuous supplementation to become significant [12].

Liposomal glutathione: 250-1,000 mg/day. The same dosing range as standard glutathione; may not require as long to show effects due to potentially improved absorption, though this is not conclusively demonstrated [15][16].

S-acetyl glutathione: 200-600 mg/day is the typical supplemental range. Evidence of superiority over standard glutathione is lacking [17].

NAC Dosing (as Glutathione Precursor)

• General antioxidant support: 600-1,200 mg/day in divided doses [9][18]
• Respiratory conditions (COPD): 600-1,200 mg/day (PANTHEON trial used 600 mg twice daily) [43][44]
• Psychiatric conditions: 1,200-2,400 mg/day (most trials used 2,000-2,400 mg/day) [72][73][74]
• Male fertility: 600 mg/day [69]
• Immune support in elderly: 600-1,200 mg/day [40]

GlyNAC Dosing

The Kumar et al. studies used weight-based dosing of approximately 100 mg/kg/day each of glycine and NAC, which for a 70 kg adult translates to approximately 7 g glycine + 7 g NAC daily, taken in divided doses [10][21]. This is a high dose and was used in a research setting. More practical doses for general supplementation have not been established.

Timing and Practical Considerations

• Glutathione: Take on an empty stomach (between meals) for best absorption [1]
• NAC: Can be taken with or without food. Some people experience GI discomfort and prefer taking it with meals. The sulfur smell/taste can be unpleasant; capsules or tablets help mask this
• Split dosing: For doses above 600 mg of either glutathione or NAC, splitting into two daily doses may improve tolerance and absorption
• Duration: Oral glutathione requires 3-6 months for significant effect on blood levels [12]. NAC typically shows effects within 2-4 weeks [9]

Safety and Side Effects

Oral Glutathione

Glutathione has generally been reported to be well-tolerated in clinical trials. Reported side effects include [1][29]:

• Flatulence
• Loose stools
• Skin rash (rare)
• Flushing (rare)

These side effects have generally been mild and self-limiting. The Richie et al. (2015) 6-month trial at doses up to 1,000 mg/day reported no significant adverse events [12]. Long-term safety studies (beyond 6 months) do not appear to have been conducted for oral glutathione [1].

NAC Safety

NAC has a much longer safety record due to decades of clinical use. It is generally well-tolerated, with the following side effects [9][18]:

• GI symptoms (most common): Nausea, vomiting, diarrhea, and abdominal discomfort, particularly at doses above 1,200 mg/day
• Sulfurous taste/smell: NAC has a distinct sulfur odor and taste that some find unpleasant
• Headache: Occasionally reported
• Anaphylactoid reactions (IV use only): Infusion-related reactions including flushing, itching, bronchospasm, and hypotension occur in approximately 10-20% of patients receiving IV NAC for acetaminophen overdose [18]

Upper limit: There is no established UL for NAC. Clinical trials have used doses up to 8,000 mg/day for extended periods. Most clinical applications use 600-2,400 mg/day [9][18][20].

Intravenous Glutathione

IV glutathione carries additional risks beyond oral supplementation [60]:

• Skin rashes
• Abdominal pain
• Thyroid dysfunction
• Liver dysfunction
• Kidney dysfunction and possible kidney failure
• Stevens-Johnson syndrome (rare)

These risks have been documented particularly in the context of IV glutathione used for cosmetic skin lightening, where it may be administered repeatedly at high doses (600-2,400 mg per session) [60]. Several regulatory agencies in Asia have issued warnings against this practice.

Theoretical Cancer Concern

Glutathione supplementation could theoretically protect cancer cells from chemotherapy and radiation therapy. This has not been demonstrated in clinical practice with oral glutathione at standard supplemental doses, but preclinical evidence warrants caution in cancer patients undergoing active treatment [2][5]. Individuals with active cancer should consult their oncologist before supplementing with glutathione or NAC.

Pregnancy and Lactation

Limited safety data exists for glutathione supplementation during pregnancy. NAC has been used safely during pregnancy in clinical settings (e.g., for acetaminophen overdose) and in some research trials for PCOS and recurrent pregnancy loss. Nonetheless, supplementation should be discussed with a healthcare provider [9][18].

Kidney Disease

Individuals with advanced chronic kidney disease should exercise caution with glutathione and NAC supplementation. While NAC has been studied for renal protection (contrast-induced nephropathy), dosing adjustments may be necessary in severe renal impairment, and monitoring is advisable [67][68].

Drug Interactions

NAC-Drug Interactions

NAC has several clinically relevant drug interactions [9][18]:

Drug	Interaction	Clinical Significance
Nitroglycerin	NAC potentiates the vasodilatory effect of nitroglycerin, increasing risk of hypotension and severe headache	Significant. Monitor blood pressure closely if combining. Space doses apart [9].
Activated charcoal	Charcoal may adsorb oral NAC, reducing its efficacy	Separate administration by at least 1-2 hours [18].
Carbamazepine	NAC may reduce carbamazepine levels	Monitor drug levels if combining [9].
ACE inhibitors	Theoretical potentiation of hypotensive effects	Monitor blood pressure [9].
Chemotherapy agents	NAC may theoretically reduce efficacy of alkylating agents and platinum compounds	Avoid during active chemotherapy unless directed by oncologist [2][5].
Anticoagulants	NAC may have mild antiplatelet effects at high doses	Use caution in patients on warfarin or other anticoagulants; monitor INR [18].

Glutathione-Drug Interactions

Fewer drug interactions have been specifically documented for oral glutathione supplements compared to NAC, likely because oral glutathione achieves lower systemic levels. However, the same theoretical concerns regarding chemotherapy agents apply [2][5].

Interactions with Other Supplements

• Vitamin C: Synergistic — vitamin C spares glutathione and helps regenerate it from GSSG. No negative interaction [24].
• Alpha-lipoic acid: Synergistic — ALA upregulates glutathione synthesis and recycles glutathione. No negative interaction [25].
• Iron: NAC may enhance iron absorption due to its reducing properties. Individuals with iron overload disorders (hemochromatosis) should use NAC with caution [9].
• Selenium: Synergistic — selenium is required for glutathione peroxidase activity. No negative interaction [26].

Dietary Sources

The body synthesizes glutathione endogenously, so dietary intake is supplementary rather than essential. However, several foods provide glutathione directly or supply the amino acid precursors needed for its synthesis.

Foods Containing Glutathione

Food	Glutathione Content (mg per serving)	Notes
Asparagus (cooked, 1 cup)	28.3	Highest vegetable source [78]
Avocado (1 medium)	27.7	Also rich in monounsaturated fats [78]
Spinach (cooked, 1 cup)	14.0	Raw spinach has approximately 11 mg [78]
Okra (cooked, 1 cup)	14.0	Common in Southern and Asian cuisines [78]
Broccoli (cooked, 1 cup)	9.6	Also provides sulforaphane for Nrf2 activation [27][78]
Cantaloupe (1 cup)	7.6	Seasonal availability [78]
Tomato (1 medium)	5.8	Cooking may reduce glutathione content [78]
Orange (1 medium)	5.6	Also provides vitamin C for GSH sparing [78]
Walnuts (1 oz)	3.5	Also provides omega-3 alpha-linolenic acid [78]
Milk (1 cup)	2.3	Whey component provides cysteine precursors [22][78]

Source: Jones et al., Nutr Cancer, 1992; estimated from USDA databases [78].

Foods Rich in Glutathione Precursors

Since cysteine availability is the rate-limiting factor for glutathione synthesis, foods rich in cysteine and sulfur-containing amino acids are particularly important [2][9]:

• High-cysteine protein sources: Whey protein, eggs, chicken, turkey, pork, beef, fish
• Sulfur-rich vegetables (also activate Nrf2): Broccoli, Brussels sprouts, cauliflower, kale, cabbage, garlic, onions, shallots
• Glycine-rich foods (collagen sources): Bone broth, gelatin, skin-on chicken, pork rinds
• Glutamic acid sources: Tomatoes, mushrooms, parmesan cheese, soy sauce, fermented foods

Practical Notes

• Cooking reduces glutathione: Raw fruits and vegetables contain more glutathione than cooked versions. Steaming preserves more glutathione than boiling [78].
• Alcohol depletes glutathione: Chronic alcohol consumption severely reduces hepatic glutathione through increased oxidative stress during ethanol metabolism [6][35].
• Cruciferous vegetables are dual-acting: They provide some dietary glutathione directly AND activate Nrf2-mediated upregulation of glutathione synthesis genes via sulforaphane [27][28].
• A food-first approach for glutathione support focuses on adequate protein intake (for cysteine, glycine, and glutamic acid), abundant fruits and vegetables (for direct glutathione and vitamin C), and regular intake of cruciferous vegetables (for Nrf2 activation).

References

1. ConsumerLab. "Glutathione Supplements Review." Accessed 2026. https://www.consumerlab.com/reviews/glutathione-supplements/glutathione/

2. Lu SC. "Glutathione synthesis." Biochim Biophys Acta. 2013;1830(5):3143-3153. https://doi.org/10.1016/j.bbagen.2012.09.008

3. Forman HJ, Zhang H, Rinna A. "Glutathione: overview of its protective roles, measurement, and biosynthesis." Mol Aspects Med. 2009;30(1-2):1-12. https://doi.org/10.1016/j.mam.2008.08.006

4. Meister A, Anderson ME. "Glutathione." Annu Rev Biochem. 1983;52:711-760. https://doi.org/10.1146/annurev.bi.52.070183.003431

5. Traverso N, Ricciarelli R, Nitti M, et al. "Role of glutathione in cancer progression and chemoresistance." Oxid Med Cell Longev. 2013;2013:972913. https://doi.org/10.1155/2013/972913

6. Yuan L, Kaplowitz N. "Glutathione in liver diseases and hepatotoxicity." Mol Aspects Med. 2009;30(1-2):29-41. https://doi.org/10.1016/j.mam.2008.08.003

7. Dröge W, Breitkreutz R. "Glutathione and immune function." Proc Nutr Soc. 2000;59(4):595-600. https://doi.org/10.1017/S0029665100000847

8. Ghezzi P. "Role of glutathione in immunity and inflammation in the lung." Int J Gen Med. 2011;4:105-113. https://doi.org/10.2147/IJGM.S15618

9. Mokhtari V, Afsharian P, Shahhoseini M, et al. "A review on various uses of N-acetyl cysteine." Cell J. 2017;19(1):11-17. https://doi.org/10.22074/cellj.2016.4872

10. Kumar P, Liu C, Hsu JW, et al. "GlyNAC supplementation in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, genotoxicity, muscle strength, and cognition." Clin Transl Med. 2021;11(3):e372. https://doi.org/10.1002/ctm2.372

11. Sekhar RV, Patel SG, Guthikonda AP, et al. "Deficient synthesis of glutathione underlies oxidative stress in aging." Am J Clin Nutr. 2011;94(3):847-853. https://doi.org/10.3945/ajcn.110.003483

12. Richie JP Jr, Nichenametla S, Neiber W, et al. "Randomized controlled trial of oral glutathione supplementation on body stores of glutathione." Eur J Nutr. 2015;54(2):251-263. https://doi.org/10.1007/s00394-014-0706-z

13. Witschi A, Reddy S, Stofer B, Lauterburg BH. "The systemic availability of oral glutathione." Eur J Clin Pharmacol. 1992;43(6):667-669. https://doi.org/10.1007/BF02284971

14. Park EY, Shimura N, Konishi T, et al. "Increase in the protein-bound form of glutathione in human blood after oral administration." J Agric Food Chem. 2014;62(26):6183-6189. https://doi.org/10.1021/jf501338z

15. Sinha R, Sinha I, Calcagnotto A, et al. "Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function." Eur J Clin Nutr. 2018;72(1):105-111. https://doi.org/10.1038/ejcn.2017.132

16. Buonocore D, Grosini M, Giardina S, et al. "Bioavailability study of an innovative orobuccal formulation of glutathione." Oxid Med Cell Longev. 2016;2016:3286365. https://doi.org/10.1155/2016/3286365

17. Cavallaro RA, Nicchia E, Semplici B, et al. "S-acetyl-glutathione oral bioavailability." Int J Clin Nutr Diet. 2018;4:133. https://doi.org/10.15344/2456-8171/2018/133

18. Millea PJ. "N-acetylcysteine: multiple clinical applications." Am Fam Physician. 2009;80(3):265-269. https://pubmed.ncbi.nlm.nih.gov/19621836/

19. Bridgeman MM, Marsden M, MacNee W, et al. "Cysteine and glutathione concentrations in plasma and bronchoalveolar lavage fluid after treatment with N-acetylcysteine." Thorax. 1991;46(1):39-42. https://doi.org/10.1136/thx.46.1.39

20. Dodd S, Dean O, Copolov DL, et al. "N-acetylcysteine for antioxidant therapy: pharmacology and clinical utility." Expert Opin Biol Ther. 2008;8(12):1955-1962. https://doi.org/10.1517/14712590802477937

21. Kumar P, Osahon OW, Sekhar RV. "GlyNAC supplementation in old mice improves brain glutathione deficiency, oxidative stress, glucose uptake, mitochondrial dysfunction." J Gerontol A Biol Sci Med Sci. 2023;78(10):1757-1768. https://doi.org/10.1093/gerona/glad081

22. Micke P, Beeh KM, Buhl R. "Effects of long-term supplementation with whey proteins on plasma glutathione levels of HIV-infected patients." Eur J Clin Invest. 2001;31(2):171-178. https://doi.org/10.1046/j.1365-2362.2001.00781.x

23. Bounous G, Batist G, Gold P. "Whey proteins in cancer prevention." Cancer Lett. 1991;57(2):91-94. https://doi.org/10.1016/0304-3835(91)90200-2

24. Lenton KJ, Sané AT, Therriault H, et al. "Vitamin C augments lymphocyte glutathione in subjects with ascorbate deficiency." Am J Clin Nutr. 2003;77(1):189-195. https://doi.org/10.1093/ajcn/77.1.189

25. Suh JH, Shenvi SV, Dixon BM, et al. "Decline in transcriptional activity of Nrf2 causes age-related loss of glutathione synthesis." Proc Natl Acad Sci. 2004;101(10):3381-3386. https://doi.org/10.1073/pnas.0400282101

26. Rayman MP. "Selenium and human health." Lancet. 2012;379(9822):1256-1268. https://doi.org/10.1016/S0140-6736(11)61452-9

27. Fahey JW, Zhang Y, Talalay P. "Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens." Proc Natl Acad Sci. 1997;94(19):10367-10372. https://doi.org/10.1073/pnas.94.19.10367

28. Riedl MA, Saxon A, Diaz-Sanchez D. "Oral sulforaphane increases Phase II antioxidant enzymes in the human upper airway." Clin Immunol. 2009;130(3):244-251. https://doi.org/10.1016/j.clim.2008.10.007

29. Allen J, Bradley RD. "Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers." J Altern Complement Med. 2011;17(9):827-833. https://doi.org/10.1089/acm.2010.0716

30. Kumar P, Liu C, Suliburk J, et al. "Supplementing GlyNAC in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, physical function, and aging hallmarks." Antioxidants. 2020;9(10):984. https://doi.org/10.3390/antiox9100984

31. Kumar P, Osahon OW, Sekhar RV. "GlyNAC supplementation in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, and aging hallmarks." Aging. 2023. https://doi.org/10.18632/aging.205177

32. Smilkstein MJ, Knapp GL, Kulig KW, Rumack BH. "Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose." N Engl J Med. 1988;319(24):1557-1562. https://doi.org/10.1056/NEJM198812153192401

33. Khoshbaten M, Aliasgarzadeh A, Masnadi K, et al. "N-acetylcysteine improves liver function in patients with non-alcoholic fatty liver disease." Hepat Mon. 2010;10(1):12-16. https://pubmed.ncbi.nlm.nih.gov/22308119/

34. Baumgardner JN, Shankar K, Hennings L, et al. "N-acetylcysteine attenuates progression of liver pathology in a rat model of nonalcoholic steatohepatitis." J Nutr. 2008;138(10):1872-1879. https://doi.org/10.1093/jn/138.10.1872

35. Fernandez-Checa JC, Kaplowitz N, Garcia-Ruiz C, et al. "GSH transport in mitochondria: defense against TNF-induced oxidative stress and alcohol-induced defect." Am J Physiol. 1997;273(1 Pt 1):G7-17. https://doi.org/10.1152/ajpgi.1997.273.1.G7

36. Nguyen-Khac E, Thevenot T, Piquet MA, et al. "Glucocorticoids plus N-acetylcysteine in severe alcoholic hepatitis." N Engl J Med. 2011;365(19):1781-1789. https://doi.org/10.1056/NEJMoa1101214

37. Flora SJ, Pachauri V. "Chelation in metal intoxication." Int J Environ Res Public Health. 2010;7(7):2745-2788. https://doi.org/10.3390/ijerph7072745

38. Herzenberg LA, De Rosa SC, Dubs JG, et al. "Glutathione deficiency is associated with impaired survival in HIV disease." Proc Natl Acad Sci. 1997;94(5):1967-1972. https://doi.org/10.1073/pnas.94.5.1967

39. De Rosa SC, Zaretsky MD, Dubs JG, et al. "N-acetylcysteine replenishes glutathione in HIV infection." Eur J Clin Invest. 2000;30(10):915-929. https://doi.org/10.1046/j.1365-2362.2000.00736.x

40. De Flora S, Grassi C, Carati L. "Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment." Eur Respir J. 1997;10(7):1535-1541. https://doi.org/10.1183/09031936.97.10071535

41. Rank N, Michel C, Haertel C, et al. "N-acetylcysteine increases liver blood flow and improves liver function in septic shock patients." Crit Care Med. 2000;28(12):3799-3807. https://doi.org/10.1097/00003246-200012000-00006

42. Lai ZW, Hanczko R, Bonilla E, et al. "N-acetylcysteine reduces disease activity by blocking mTOR in T cells from SLE patients." Arthritis Rheum. 2012;64(9):2937-2946. https://doi.org/10.1002/art.34502

43. Poole P, Sathananthan K, Fortescue R. "Mucolytic agents versus placebo for chronic bronchitis or COPD." Cochrane Database Syst Rev. 2019;5(5):CD001287. https://doi.org/10.1002/14651858.CD001287.pub6

44. Zheng JP, Wen FQ, Bai CX, et al. "Twice daily N-acetylcysteine 600 mg for exacerbations of COPD (PANTHEON)." Lancet Respir Med. 2014;2(3):187-194. https://doi.org/10.1016/S2213-2600(13)70286-8

45. Martinez FJ, de Andrade JA, Anstrom KJ, et al. "Randomized trial of acetylcysteine in idiopathic pulmonary fibrosis." N Engl J Med. 2014;370(22):2093-2101. https://doi.org/10.1056/NEJMoa1401739

46. Oldham JM, Ma SF, Martinez FJ, et al. "TOLLIP, MUC5B, and the response to N-acetylcysteine among individuals with IPF." Am J Respir Crit Care Med. 2015;192(12):1475-1482. https://doi.org/10.1164/rccm.201505-1010OC

47. Griese M, Ramakers J, Krasselt A, et al. "Improvement of alveolar glutathione and lung function but not oxidative state in cystic fibrosis." Am J Respir Crit Care Med. 2004;169(7):822-828. https://doi.org/10.1164/rccm.200308-1104OC

48. Mandal PK, Saharan S, Tripathi M, Murari G. "Brain glutathione levels -- a novel biomarker for mild cognitive impairment and Alzheimer's disease." Biol Psychiatry. 2015;78(10):702-710. https://doi.org/10.1016/j.biopsych.2015.04.005

49. Sian J, Dexter DT, Lees AJ, et al. "Alterations in glutathione levels in Parkinson's disease." Ann Neurol. 1994;36(3):348-355. https://doi.org/10.1002/ana.410360305

50. Sechi G, Deledda MG, Bua G, et al. "Reduced intravenous glutathione in the treatment of early Parkinson's disease." Prog Neuropsychopharmacol Biol Psychiatry. 1996;20(7):1159-1170. https://doi.org/10.1016/S0278-5846(96)00103-0

51. Hauser RA, Lyons KE, McClain T, et al. "Randomized, double-blind, pilot evaluation of intravenous glutathione in Parkinson's disease." Mov Disord. 2009;24(7):979-983. https://doi.org/10.1002/mds.22401

52. Mischley LK, Lau RC, Shankland EG, et al. "Phase IIb study of intranasal glutathione in Parkinson's disease." J Parkinsons Dis. 2017;7(2):289-299. https://doi.org/10.3233/JPD-161040

53. Monti DA, Newberg AB, Forehand V, et al. "N-acetyl cysteine may support dopamine neurons in Parkinson's disease." PLoS One. 2016;11(6):e0157602. https://doi.org/10.1371/journal.pone.0157602

54. Adair JC, Knoefel JE, Morgan N. "Controlled trial of N-acetylcysteine for patients with probable Alzheimer's disease." Neurology. 2001;57(8):1515-1517. https://doi.org/10.1212/WNL.57.8.1515

55. Kalamkar S, Acharya J, Kolappurath Moothan N, et al. "Randomized clinical trial of how long-term glutathione supplementation offers protection from oxidative damage and improves HbA1c in elderly type 2 diabetic patients." Antioxidants. 2022;11(5):1026. https://doi.org/10.3390/antiox11051026

56. Shahidi F, Vafaei-Nezhad S, Saeidi M, et al. "Effect of N-acetylcysteine on glycemic and oxidative stress markers in type 2 diabetic patients." J Diabetes Metab Disord. 2020;19(2):1135-1142. https://doi.org/10.1007/s40200-020-00618-0

57. Sarkaki A, et al. "N-acetylcysteine supplementation and glycemic control: a systematic review and meta-analysis." Clin Nutr ESPEN. 2021;46:56-64. https://doi.org/10.1016/j.clnesp.2021.10.008

58. Rizk AY, Bedaiwy MA, Al-Inany HG. "N-acetyl-cysteine is a novel adjuvant to clomiphene citrate in PCOS." Fertil Steril. 2005;83(2):367-370. https://doi.org/10.1016/j.fertnstert.2004.07.960

59. Thakker D, Raval A, Patel I, Walia R. "N-acetylcysteine for polycystic ovary syndrome: a systematic review and meta-analysis." Obstet Gynecol Int. 2015;2015:817849. https://doi.org/10.1155/2015/817849

60. Sonthalia S, Daulatabad D, Sarkar R. "Glutathione as a skin whitening agent: Facts, myths, evidence and controversies." Indian J Dermatol Venereol Leprol. 2016;82(3):262-272. https://doi.org/10.4103/0378-6323.179088

61. Arjinpathana N, Asawanonda P. "Glutathione as an oral whitening agent: a randomized, double-blind, placebo-controlled study." J Dermatolog Treat. 2012;23(2):97-102. https://doi.org/10.3109/09546631003801619

62. Watanabe F, Hashizume E, Chan GP, Kamimura A. "Skin-whitening and skin-condition-improving effects of topical oxidized glutathione." Clin Cosmet Investig Dermatol. 2014;7:267-274. https://doi.org/10.2147/CCID.S68424

63. Sitohang IBS, et al. "Combination of glutathione, vitamin C, alpha-lipoic acid, and zinc for skin lightening." J Clin Aesthet Dermatol. 2021;14(5):30-33. https://pubmed.ncbi.nlm.nih.gov/34188739/

64. Zubair S, Hafeez S, et al. "Efficacy of intravenous glutathione vs. placebo for skin lightening." J Pakistan Assoc Dermatol. 2016;26(3):177-181.

65. Andrews NP, Prasad A, Quyyumi AA. "N-acetylcysteine improves coronary and peripheral vascular function." J Am Coll Cardiol. 2001;37(1):117-123. https://doi.org/10.1016/S0735-1097(00)01093-7

66. Ventura P, Panini R, Abbati G, et al. "Urinary and plasma homocysteine and cysteine levels during prolonged oral N-acetylcysteine therapy." Pharmacology. 2003;68(2):105-114. https://doi.org/10.1159/000069530

67. Gonzales DA, et al. "A meta-analysis of N-acetylcysteine in contrast-induced nephrotoxicity." BMC Med. 2007;5:32. https://doi.org/10.1186/1741-7015-5-32

68. ACT Investigators. "Acetylcysteine for prevention of renal outcomes in patients undergoing coronary and peripheral vascular angiography." Circulation. 2011;124(11):1250-1259. https://doi.org/10.1161/CIRCULATIONAHA.111.038943

69. Ciftci H, Verit A, Savas M, et al. "Effects of N-acetylcysteine on semen parameters and oxidative/antioxidant status." Urology. 2009;74(1):73-76. https://doi.org/10.1016/j.urology.2009.02.034

70. Smits RM, et al. "Antioxidants for male subfertility." Cochrane Database Syst Rev. 2019;3(3):CD007411. https://doi.org/10.1002/14651858.CD007411.pub4

71. Cheraghi E, et al. "N-acetylcysteine improves oocyte and embryo quality in polycystic ovary syndrome patients." Cell J. 2019;21(1):53-59. https://doi.org/10.22074/cellj.2019.5702

72. Afshar H, et al. "N-acetylcysteine add-on treatment in refractory OCD." J Clin Psychopharmacol. 2012;32(6):797-803. https://doi.org/10.1097/JCP.0b013e318272677d

73. Fernandes BS, et al. "N-acetylcysteine in depressive symptoms and functionality: a systematic review and meta-analysis." J Clin Psychiatry. 2016;77(4):e457-466. https://doi.org/10.4088/JCP.15r09984

74. Berk M, et al. "N-acetyl cysteine for depressive symptoms in bipolar disorder." Biol Psychiatry. 2008;64(6):468-475. https://doi.org/10.1016/j.biopsych.2008.04.022

75. Yolland CO, et al. "Meta-analysis of randomised controlled trials with N-acetylcysteine in schizophrenia." Aust N Z J Psychiatry. 2020;54(5):453-466. https://doi.org/10.1177/0004867419893439

76. Gray KM, et al. "A double-blind randomized controlled trial of N-acetylcysteine in cannabis-dependent adolescents." Am J Psychiatry. 2012;169(8):805-812. https://doi.org/10.1176/appi.ajp.2012.12010055

77. Riga MG, et al. "Transtympanic injections of N-acetylcysteine for the prevention of cisplatin-induced ototoxicity." Am J Clin Oncol. 2013;36(1):1-6. https://doi.org/10.1097/COC.0b013e3182350e58

78. Jones DP, Coates RJ, Flagg EW, et al. "Glutathione in foods listed in the National Cancer Institute's Health Habits and History Food Frequency Questionnaire." Nutr Cancer. 1992;17(1):57-75. https://doi.org/10.1080/01635589209514174