Glutathione
Research reviewed: Up until 03/2026
Glutathione is a dietary supplement with 4 published peer-reviewed studies involving 186 participants, researched for Antioxidant/Immunity, Skin.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Antioxidant/Immunity
ModerateSkin
ModerateResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Antioxidant/Immunity
To investigate the effects of long-term oral glutathione (a key antioxidant that protects cells from damage) supplementation on increasing glutathione levels in different parts of the body, and whether this leads to reduced oxidative stress (cell damage caused by harmful molecules) and improved immune function (the body’s ability to fight infections and stay healthy).
Study Type
Randomized, double-blind, placebo-controlled trial
Purpose
To investigate the effects of long-term oral glutathione (a key antioxidant that protects cells from damage) supplementation on increasing glutathione levels in different parts of the body, and whether this leads to reduced oxidative stress (cell damage caused by harmful molecules) and improved immune function (the body’s ability to fight infections and stay healthy).
Dose
250 mg/day (low-dose) or 1,000 mg/day (high-dose) oral glutathione, or placebo
Participants
54 healthy non-smoking adults
Duration
6 months
Results
After 6 months, glutathione levels significantly increased by 30–35% in red blood cells, plasma (the liquid part of blood), and lymphocytes (immune cells), and by a much larger 260% in buccal cells (cells from the inside of the mouth) in the high-dose group. In the low-dose group, levels also significantly increased by 17% in blood and 29% in red blood cells. These improvements depended on the dose and duration, and levels returned to normal after stopping supplementation for 1 month. The oxidative stress levels also significantly decreased, suggesting reduced cell stress and better antioxidant protection. In addition, natural killer (NK) cell activity (immune cells that destroy infected or abnormal cells) significantly increased more than 2x in the high-dose group compared to placebo after 3 months, indicating improved immune defense.
To investigate the effects of oral liposomal glutathione (a form of glutathione, an important antioxidant, packaged in tiny fat bubbles called liposomes to help it be better absorbed in the body) on glutathione levels, immune function, and oxidative stress markers (signs of cell damage caused by harmful molecules called free radicals) in healthy adults
Study Type
Pilot clinical study (uncontrolled)
Purpose
To investigate the effects of oral liposomal glutathione (a form of glutathione, an important antioxidant, packaged in tiny fat bubbles called liposomes to help it be better absorbed in the body) on glutathione levels, immune function, and oxidative stress markers (signs of cell damage caused by harmful molecules called free radicals) in healthy adults
Dose
500 mg/day or 1,000 mg/day oral liposomal glutathione
Participants
12 healthy adults
Duration
1 month
Results
Researchers observed significant increases in glutathione levels after supplementation, with levels significantly rising after 1 week and reaching up to 40% in whole blood, 25% in red blood cells, 28% in plasma (liquid part of the blood), and 100% in immune cells after 2 weeks. At the same time, oxidative stress (cell damage caused by harmful molecules) decreased, shown by a 35% drop in 8-isoprostane (a marker of fat damage in cells) and a 20% decrease in the oxidized to reduced glutathione ratio (an indicator of overall cell stress). Immune function also improved significantly, with natural killer cell activity (cells that destroy infected or abnormal cells) increasing by up to 400% and lymphocyte proliferation (the ability of immune cells to multiply and respond) increasing by up to 60% after 2 weeks.
Skin
To determine the effects of oral glutathione on skin melanin content in healthy volunteers
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To determine the effects of oral glutathione on skin melanin content in healthy volunteers
Dose
500 mg/day oral glutathione (2 x 250 mg) or placebo
Participants
60 healthy medical students
Duration
4 weeks
Results
At 4 weeks, the melanin indices decreased consistently at all six sites in subjects who received glutathione. The reductions were statistically significantly greater than those receiving placebo at two sites, namely the right side of the face and the sun-exposed left forearm. No significant changes were observed in the placebo group.
How They Measured It
Melanin indices (a measure of how much skin pigment is present) were measured at six sites—commonly areas like the face, forearm, upper arm, forehead, cheek, and neck—to compare pigmentation across more exposed and less-exposed skin. These were measured using a Mexameter, a non-invasive device that uses reflected light to objectively assess melanin levels; a lower index means less dark pigment.
To compare the effects of oral reduced glutathione (the active antioxidant form) and oral oxidized glutathione (the inactive form produced when GSH neutralises free radicals) at lower doses than previous studies, on skin melanin, wrinkles, and skin elasticity in healthy female volunteers.
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To compare the effects of oral reduced glutathione (the active antioxidant form) and oral oxidized glutathione (the inactive form produced when GSH neutralises free radicals) at lower doses than previous studies, on skin melanin, wrinkles, and skin elasticity in healthy female volunteers.
Dose
oral reduced glutathione (GSH) 250 mg/day, oral oxidized glutathione (GSSG) 250 mg/day, or placebo
Participants
60 healthy female volunteers
Duration
12 weeks
Results
Researchers observed that epidermal water loss (a measure of how much moisture escapes from the skin; lower means better hydration and skin barrier) on the sun-exposed right forearm was significantly lower in the GSH group than the GSSG group (P = 0.044), suggesting better moisture retention. They also found that Visioscan measurements (a method that analyzes skin texture and smoothness) on the sun-protected left arm were significantly lower in the GSH group compared to placebo, indicating smoother, healthier-looking skin.
How They Measured It
Melanin indices (a measure of how much skin pigment is present) were measured at six sites—commonly areas like the face, forearm, upper arm, forehead, cheek, and neck—to compare pigmentation across more exposed and less-exposed skin. These were measured using a Mexameter, a non-invasive device that uses reflected light to objectively assess melanin levels; a lower index means less dark pigment.
Frequently Asked Questions
Common questions about Glutathione research
There are currently 4 peer-reviewed studies on Glutathione (Glutathione), involving 186 total participants. Research covers Antioxidant/Immunity, Skin. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (4 human studies), and reported outcomes.
Glutathione has been researched for: Antioxidant/Immunity, Skin. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 4 out of 4 studies are human trials. Human trials carry more weight in our evidence scoring system.
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