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• Hydroxytyrosol (HT) supplementation at 15 mg/day for 16 weeks significantly reduced oxidized LDL, protein oxidative damage, and DNA oxidation markers in overweight adults with prediabetes.
• HT prevented declines in total antioxidant capacity and glutathione peroxidase activity, supporting sustained antioxidant defense.
• An anti-inflammatory effect was demonstrated by significant reductions in circulating interleukin-6 (IL-6) levels.
• No changes were seen in lipid profile, body weight, or lifestyle factors, and no adverse events occurred, indicating safety and tolerability.
