Glutathione
Glutathione is an antioxidant found in all cells and tissues of the human body. Although it is essential for many physiological processes, its use as a dietary supplement is limited because it is rapidly broken down after oral administration. L-cysteine, a metabolite of glutathione, can increase the body's glutathione levels, but obtaining L-cysteine through the glutathione pathway is inefficient and costly.
Glutathione is most commonly used for cardiovascular health. It also has applications in immune and metabolic health.
Dosage information
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Glutathione is most commonly used for cardiovascular health.
Glutathione ( γ-L-glutamyl-L-cysteine ) is a small amino acid molecule (peptide) composed of one L-glutamic acid molecule, one L-cysteine molecule, and one glycine molecule. This molecule is present in food and the human body, where it acts as an antioxidant. The glutathione system includes the enzymes that synthesize glutathione within cells, as well as specialized enzymes that utilize glutathione to exert its antioxidant effects. Glutathione supplementation is believed to maintain intracellular glutathione levels, thereby maintaining the effectiveness of the entire glutathione system. Despite its broad role in cell biology, glutathione's current application in nutritional supplementation is limited due to the following pharmacokinetic properties:
- Glutathione may be partially absorbed from the intestine in its intact form, but it cannot enter cells intact. It must first be metabolized to form L-cysteine (two L-cysteine molecules linked together) before it can be absorbed.
- The synthesis of glutathione can be increased simply by providing L-cysteine within the cell, while N-acetycysteine can achieve this goal more effectively at a lower cost than glutathione.
In fact, glutathione is an indirect and expensive way to supplement L-cysteine through diet. Dietary protein itself, including sources rich in L-cysteine such as whey protein, can effectively increase the intake of L-cysteine in the diet, but it is not very efficient; while N-acetycysteine is more effective and cheaper than glutathione.
Although oral glutathione supplements do not effectively increase intracellular glutathione levels for the reasons mentioned above, they are fully absorbed into the bloodstream. Since elevated blood glutathione levels have been shown to slow the breakdown of nitric oxide, glutathione supplementation may help enhance the effects of nitric oxide promoters such as L-citrulline or L-arginine.
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California Gold Nutrition, L-Glutathione (Reduced), 500 mg, 120 Vegan Capsules
It contains L-Glutathione Reduced , a powerful antioxidant that helps neutralize free radicals and protect cells from oxidative stress; it supports liver detoxification and maintains cellular health and the immune system ; it is also commonly used to promote skin health and radiance , in conjunction with daily nutritional supplements.
NOW Foods, Glutathione, 250 mg, 60 plant-based capsules
Contains glutathione , an important antioxidant for the human body, which helps neutralize free radicals and reduce oxidative stress; supports liver detoxification function and immune system health , and helps maintain skin condition and cell health , making it suitable for daily antioxidant nutritional supplementation.
Swanson, L-Glutathione, 100 mg, 100 capsules
Contains L-Glutathione , an important antioxidant nutrient in the body that helps fight free radicals and reduce oxidative stress; supports liver detoxification and immune system health , and helps maintain skin condition and cell repair . It can be used as a daily antioxidant and health management supplement.
Codeage, Liposomes, Glutathione, 60 Vegan Capsules
Calcium, magnesium, and zinc, combined with vitamin D3, support bone, muscle, and immune health, and are of reliable quality.
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Dosage information
Glutathione is an important antioxidant that is naturally present in the human body and participates in detoxification, immune regulation, and oxidative stress control.
Oral supplements (common in research and practice)
250–1,000 mg daily
Commonly taken once daily or divided into two doses.
Because glutathione itself has a limited absorption rate in the intestine, different studies have yielded inconsistent results regarding its oral efficacy.
Intravenous injection (IV) :
- For clinical or research environments
- It can significantly increase the level of glutathione in the blood.
- Not for general supplementary use
Inhalation or topical use :
- Found only for specific research or medical purposes
- The relevant dosage and effects have not yet been standardized.
Because the absorption of orally administered glutathione is limited, the following methods are often used in studies to indirectly increase glutathione levels in the body :
- N-acetylcysteine (NAC)
- α-Lipoic acid
- Vitamin C, Vitamin E
These precursors or co-nutrients have shown in some studies to more stably increase glutathione levels in the body.
- It can generally be taken with meals or on an empty stomach.
- Some products utilize liposome technology to improve absorption rates, but related research remains limited.
It is not recommended to take this product concurrently with glutathione.
Glutathione is a strong antioxidant and may theoretically interfere with the oxidative killing mechanism of chemotherapy/radiotherapy .
Example : During cancer chemotherapy and radiation therapy
Recommendation : Use only with the approval of the attending physician during treatment.
Glutathione may affect immune and detoxification pathways , and theoretically may interfere with the efficacy of immunosuppressive therapy.
Examples : Steroids, immunosuppressants for organ transplantation
Recommendation : Self-supplementation is not recommended; a doctor's evaluation is necessary.
Inhaled or high-dose glutathione may induce bronchoconstriction or wheezing (in a minority of people).
Example : Asthma patients
Recommendation : Avoid inhaled formulations; oral formulations should also be tested with low doses.
The combination of multiple antioxidants may cause an imbalance in redox activity (excessive antioxidant activity) , which can affect normal cell signaling.
Example : High-dose vitamins C, E, ALA + glutathione
Recommendation : Avoid simultaneous high doses; use at intervals or periodically.
High doses may cause bloating, nausea, or diarrhea .
Example : During an attack of enteritis or diarrhea
Recommendation : Supplement only after symptoms have stabilized, starting with a low dose.
- Common recommended dosage: 250–500 mg/day (oral)
- It can be combined with NAC and Vitamin C (not at the same high dose) to promote the synthesis in the body.
- Detoxification and antioxidant effects typically require 4–8 weeks of observation.
Safety Information and Side Effects
- Tolerability: For most adults, oral or topical supplements are generally considered safe in the short term.
- Dosage Form Differences (Important): Oral: High safety profile, but absorption rate is controversial (easily destroyed by stomach acid). Inhaled: Dangerous for asthma patients. Injectable (IV): High-dose injection therapy used for skin whitening has been warned by the US and Philippine FDA as potentially causing serious side effects (such as thyroid dysfunction, kidney damage, Stephen Johnson's syndrome), requiring strict physician monitoring.
- Main risks: primarily gastrointestinal discomfort and allergic reactions.
Side effects from oral supplements are usually mild:
- Gastrointestinal symptoms (most common): Abdominal cramping , bloating , increased flatulence, loose stools.
- Allergic reaction: rash and itching
- Respiratory system (inhalation): Using inhaled glutathione may trigger asthma attacks or difficulty breathing.
Pregnancy:
- Security: Security has not been established .
- Recommendation: Reliable data on the use of glutathione supplements by pregnant women are currently lacking. Although it is a naturally occurring antioxidant in the body, the effects of additional high doses are unknown, and its use is advised to be avoided .
Lactation:
- Security: Security has not been established .
- Recommendation: Due to insufficient data, it is recommended to avoid use during breastfeeding.
Asthma:
- Contraindications: This is the most important precaution. Asthma patients should avoid using inhaled glutathione, as it may trigger bronchospasm or an asthma attack. Oral formulations are generally less risky, but caution is still advised.
Risks associated with skin whitening:
- Zinc deficiency: Long-term high-dose use of glutathione may reduce the body's zinc levels (glutathione chelates zinc).
- Thyroid function: Some studies and FDA warnings indicate that long-term, high-dose glutathione injections may interfere with thyroid function.
Drug interactions:
- While few serious drug interactions are known, its potent antioxidant properties theoretically may reduce the efficacy of certain chemotherapy drugs (such as Cisplatin). If you are undergoing cancer treatment, be sure to consult your oncologist.
