Glutathione is a small molecule made of three amino acids. Cells make it and use it as their main antioxidant. Its chemistry is well mapped, but human trials of glutathione supplements are small and their results are mixed.
Why scientists study it
- It is the main antioxidant inside cells. The glutathione peroxidase (GSH-Px) enzymes cannot work without it, and it is at the center of a cell’s redox balance.
- Plain GSH taken by mouth is poorly absorbed. Scientists have tested IV, liposomal and under-the-tongue forms as other ways to deliver it.
- Its role as an antioxidant and enzyme helper is well established. Wider supplement claims, such as skin lightening, are still being tested and are not settled in peer-reviewed research.
Three studies to know
Meister & Anderson, 1983 · Annual Review of Biochemistry
This core review laid out how glutathione is made, how it cycles between forms, and what it does for enzymes. Four decades later it is still the reference for the field. Read the paper
Richie et al., 2015 · European Journal of Nutrition
In this six-month randomized, placebo-controlled trial, 54 people took 250 or 1,000 mg of oral GSH a day. GSH rose in whole blood, red blood cells, plasma and cheek cells, more so as the dose went up. Natural killer cells killed targets slightly better on the larger dose. Read the paper
Sinha et al., 2018 · European Journal of Clinical Nutrition
Healthy adults in this crossover trial took 500 or 1,000 mg of liposomal glutathione a day for one to four weeks. Their body stores of GSH went up, and so did immune function markers. It is an early sign that liposomal delivery may work. Read the paper
Safety and legal status
- The body makes glutathione. People have mostly tolerated oral forms in trials so far. Unlicensed injections have been tied to serious side effects, and no long-term safety data set exists.
- The FDA, MHRA and EMA have not approved it as a treatment, apart from specific IV products used in a few places for defined conditions.
- Supplied only for in vitro and lab research. Sales claims for pills and injections, above all for skin lightening, are still argued over in peer-reviewed research.