Glutathione Peptide (1500MG)

This page summarizes a small 2002 study in 18-month-old male rats. It tested a daily oral combination of vitamin C and glutathione (GSH), a naturally occurring tripeptide, for 6 weeks. The researchers measured oxidative stress markers, tissue glutathione, serum lipids, hormones and trace minerals. Because the two compounds were always given together, the results cannot be attributed to glutathione alone.

What Is Glutathione?

Glutathione (GSH) is a tripeptide made by cells from glutamate, cysteine and glycine. In its reduced form, it acts as a substrate for the enzymes glutathione peroxidase and glutathione-S-transferase, which take part in neutralizing reactive oxygen species and detoxifying compounds. Researchers often study tissue glutathione as one marker of a cell's antioxidant status.

Study Objective

The study asked whether a combination of vitamin C and GSH, given to older rats, would change tissue lipid peroxidation, tissue GSH, serum lipids, testosterone, thyroid hormones (T3 and T4), and copper and zinc levels. All comparisons were made between treated and untreated rats of the same age.

How the Rat Study Was Designed

The study used 18-month-old male Sprague–Dawley rats weighing 500–550 g. Rats were split into two groups of five. One group was an untreated control. The other received a mixture of GSH (100 mg/kg body weight) and vitamin C (30 mg/kg body weight) by stomach tube (intragastrically) once daily for 6 weeks. These amounts describe the published rat protocol only. At the end of the study, blood, liver, testes and brain were collected for analysis.

What Did the Glutathione Study Find? Oxidative Stress Markers

TBARS and Tissue GSH

Compared with untreated rats, the supplemented group had significantly lower TBARS in both liver and testes, which the author interpreted as lower lipid peroxidation.

Tissue GSH Differed by Organ

Testicular GSH was significantly higher in the supplemented group. Liver GSH was essentially unchanged. This organ-specific pattern means the lower liver TBARS did not come with higher liver GSH.

Values from Table 1 of the paper (n = 5 per group). *Printed as "1.164" in the original table. It is shown here as 1,164, assuming the same units as the other values.

Serum Lipids and Hormone Measurements

Serum cholesterol and triglycerides were significantly lower in the supplemented group. Serum testosterone was significantly higher. The author proposed that this related to lower oxidative stress and higher GSH in the testes, but the study did not test that link directly. Serum T3 and T4 did not differ significantly between groups.

Values from Table 2 of the paper, as printed, with units as reported by the author (n = 5 per group).

Copper and Zinc Measurements

Copper was significantly higher in the supplemented group in serum, liver, brain and testes. Zinc was significantly higher in serum and brain. Liver and testis zinc did not differ significantly. The paper's abstract says zinc rose in the testes, but its results table and text report no significant change there, so this summary follows the table.

Values from Table 3 of the paper (n = 5 per group).

The Author's Interpretation: Antioxidant Recycling

The author proposed that giving vitamin C with GSH may support an antioxidant "recycling" pathway, in which vitamin C helps regenerate reduced glutathione. This was presented as the rationale for the combination and as one interpretation of the results. The study did not measure glutathione reductase activity, oxidized glutathione (GSSG) or vitamin C levels, so the mechanism was not tested directly.

Limitations and Research Context

This is a small, short study, and several features limit what it can show:

• Only 5 rats per group, all male, of one strain and age.
• Glutathione was always given with vitamin C, so neither compound's separate contribution can be determined.
• There was no young control group, so the study could not show whether the measures were "age-related" or whether supplementation moved them toward younger values.
• Administration was by stomach tube, which differs from other routes. Results may not apply to other forms, routes or amounts.
• The paper reports a single experiment, with one inconsistency between its abstract and results (testicular zinc) and one apparent typographical error in Table 1.
• Findings in rats do not establish effects, safety or dosing in people.

Conclusion

In Amer (2002), 18-month-old male rats given a daily oral combination of vitamin C and glutathione for 6 weeks had lower TBARS in liver and testes, higher testicular GSH, lower serum cholesterol and triglycerides, higher serum testosterone, and higher copper and zinc in some tissues than untreated rats of the same age. T3, T4 and liver GSH did not change. Because of the very small groups, the combined intervention and the lack of a young comparison group, these results are preliminary.

At a Glance: What Changed vs. What Didn't (Supplemented vs. Untreated Aged Rats)