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What exactly is glutathione?
- Glutathione is a tripeptide made up of the 3 amino acids glutamic acid, cysteine and glycine
- It comes in 2 states that are transformed into each other:
- Reduced glutathione (GSH)
- Oxidized glutathione disulfide (GSSG) (2 H+ away)
- In terms of food law, it is a “functional dietary protein” (no amino acid, therefore no restriction in use)
- Glutathione can be synthesized and recycled by humans, but different building blocks are essential
- Prerequisite for glutathione synthesis and recycling
- Amino acids (L-glutamate, L-cysteine, L-glycine as well as precursors methionine and possibly N-acetylcysteine) à high dependence on cysteine availability!
- Enzymes (Ɣ-Glutamyl transpeptidase, peptidase, Ɣ-Glutamyl cyclotransferase, Ɣ-Glutamyl cysteine synthetase, GSH synthetase) à high dependence on the activity of Ɣ-Glutamyl cysteine synthetase
- Cofactorsthat support synthesis and recycling (α-lipoic acid, vitamin C, vitamin E, vitamin B2, vitamin B3, magnesium)
- energy and functional mitochondria (including cofactors such as coenzyme Q10, L-carnitine, vitamins B1, B2 and B3) à GSH synthesis is ATP-dependent
Bioavailability of oral glutathione
- Digestive tract absorbs GSH and other nutritionally useful peptides intact on (e.g. casomorphins, proteases)
- Active transport through intestinal membranes or intestinal epithelial cells demonstrated (with partial degradation to amino acids intracellularly)
- Probably also resorption as Glu-Cys dipeptide and resynthesis of the tripeptide (in the liver)
- GSH supplementation improves GSH status more than corresponding amounts of individual amino acids
- GSH performs functions in the intestine as well as in the organism extracellularly and in various cell compartments
- Healthy intestinal mucosa important for absorption of di-/tripeptides
- Reasons why some authors were unable to detect an increase in plasma GSH after oral GSH administration:
- Short GSH half-life
- No increase in GSH in case of low GSH concentration and poor redox status
(high GSH consumption for regeneration of other redox systems, such asAscorbic acid)
Effects of glutathione
Antioxidant effects
- Non-enzymatic antioxidant
- most important hydrophilic antioxidant of the cell (directly binds radicals and nitric oxide (NO) and reduces other antioxidants)
- is oxidized to GSSG (and reduced again with the help of the enzyme glutathione reductase)
- Coenzyme for enzymatic glutathione peroxidases (metalloenzymes)
- reduce toxic peroxides such as hydrogen peroxide and lipid hydroperoxides by reacting with glutathione)
- Enzymes are proteins (require amino acids, zinc, vitamins B6 and B12)
- Enzymes require activators (selenium, zinc, manganese)
- reduce toxic peroxides such as hydrogen peroxide and lipid hydroperoxides by reacting with glutathione)
Regeneration of antioxidants
Inactivation of activated oxygen
Detoxifying effects of GSH
- Glutathione in detoxification phase I
- Disposal of radical metabolites (Part of the redox network)
- Glutathione in detoxification phases II and III
- Coenzyme for glutathione S-transferases
- Binding partners of pollutants
- catches via thiol/sulfhydryl/SH group Toxins, polyvalent heavy metals such as mercury, cadmium, lead and other foreign substances
- forms Pollutant-glutathione complexeswhich are excreted as mercapturic acid derivatives via the kidneys and bile
- reduces by Complex formation with “good” trace elements pro-oxidative risk of high concentrations of these substances (z.B. Fenton reaction of iron with vitamin C)
- Note: GSH can be combined with other chelating agents such as α-lipoic acid.
Glutathione and Detoxification Phase II
Causes of glutathione deficiency and possible consequences
- Causes
- Low intake (z.B. Nutrition, absorption disorders)
- High demand (z.B. Radical exposure, pollution, illness, lifestyle errors, age, stress, sport)
- Disorders of glutathione synthesis and metabolism (z.B.Deficiency of amino acids, glutathione reductase or glutathione peroxidase)
- Follow
- Oxidative and nitrosative (NO) stress
- Energy deficiency
- Deficiency of thiol groups (-SH)
- Detoxification disorders
- Immunosuppression and susceptibility to infection
- Reperfusion injuries, increased hemolysis rates
- neurological, psychomotor, cardiovascular, ocular and hepatic disorders
Glutathione diagnostics
- Nutritional and lifestyle history
- Special symptoms
- Laboratory examination
- Total glutathione (erythrocytes): 1805-3600 μmol/l
- GSH reduced (leukocytes or erythrocytes): 962-3329 μmol/l
- GSH:GSSG ratio (serum): 99:1 to 90:10 (no statement about intracellular situation)
- Glutathione peroxidase: 4170-10880 U/L
- In case of stress/illness, the ratio GSH/GSSG initially shifts
- Long-term decrease in total glutathione
Glutathione requirement
- The exact glutathione requirement in addition to diet and self-synthesis is not exactly known and depends on many factors (supply, synthesis, individual situation)
- In case of stress/illness, the ratio GSH/GSSG initially shifts
- Long-term decrease in total glutathione
- Disturbances only become apparent when GSH levels are < 1 g (i.e., approximately 7 g are already missing from the “normal level”)
- In addition, due to ongoing stress, continued high GSH requirement
Typical glutathione dosage
| substance | Oral dosage (per day) | Parenteral dosage (per day) |
| Glutathione prevention (in case of risks) | 0.2 – 1 g | - |
| Initial glutathione therapy | 1-5 g | 400-600 mg |
| Glutathione follow-up (after therapy) | 0.6-1.2 g | - |
- Oral bioavailability is guaranteed!
(z.B. Richie JP et al.; Randomized controlled trial of oral glutathione supplementation on
body stores of glutathione; European Journal of Nutrition 2014)
Glutathione content of foods (Source: Reuss F)
| Groceries | GSH mg/kg |
| Brewer's yeast extract (fresh) | 10000 (Reiff, 1960) |