Glutathione peroxidase activity

Method

Glutathione peroxidase enzymatic activity in erythrocyte lysate, whole blood, plasma or serum, by coupled glutathione-reductase assay following NADPH consumption.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

The selenium-dependent arm of the antioxidant panel, which is why it responds to selenium status independently of anything a trial supplements. Distinct from reduced glutathione, which is a substrate concentration rather than an enzyme rate — the two carry similar names, move on different timescales, and are recorded separately for that reason.

Findings

2 findings from 2 compounds, strongest first.

• resveratrol — increases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “In addition, compared to placebo, Supplementation with resveratrol significantly increased glutathione peroxidase levels (SMD = 0.38, 95%CI(0.03, 0.74), P = 0.04; Level of evidence:low) and catalase levels (SMD = 0.33, 95%CI(0.03, 0.63), P = 0.03; Level of evidence: low).”

  Study

  meta-analysis

  Population

  patients with type 2 diabetes mellitus (T2DM)

  The efficacy of resveratrol supplementation on inflammation and oxidative stress in type-2 diabetes mellitus patients: randomized double-blind placebo meta-analysis.2024PMID:39872318

• curcumin — increases

  BLikelyGrade B, Likely. Human evidence, limited replication or design limits.Finding

  “Compared to the placebo group, curcumin supplementation significantly enhanced antioxidant defenses, as evidenced by increased levels of total antioxidant capacity (TAC), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activity at 3, 6, 9, and 12 months.”

  Study

  RCT

  Duration

  12 months

  Dose

  Oral ethanolic Curcuma longa rhizome extract standardised to 75-85% total curcuminoids, 250 mg curcuminoids per capsule, three capsules twice daily (1500 mg curcuminoids/day) for 12 months

  Population

  Obese adults with type 2 diabetes mellitus managed on metformin (age >=35 y, BMI >=23 kg/m2, HbA1c <6.5%), Nakhon Nayok, Thailand; 227 randomised, per-protocol analysis and the analysed count is not reported in the paper; secondary endpoint (declared primary outcome: liver steatosis by controlled attenuation parameter on transient elastography); GPx by RANSEL colorimetric assay

  Curcumin Attenuates Liver Steatosis via Antioxidant and Anti-Inflammatory Pathways in Obese Patients with Type 2 Diabetes Mellitus: A Randomized Controlled Trial.2025PMID:41096556Industry funded