Reduced intake of dietary antioxidants can impair antioxidant status in type 2 diabetes patients.

Abstract

Oxidative stress plays a major role in the pathogenesis of type 2 diabetes. The objective of this study was to investigate associations between dietary intake of antioxidants and antioxidant status in patients with type 2 diabetes. In 80 patients with type 2 diabetes and 37 controls, total antioxidant status (TAS), activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD), malondialdehyde (MDA), and 4‑hydroxyalkenals (4‑HAE) were measured. The 24‑hour food recall method and our own dietary database were used to calculate dietary total antioxidant capacity (DTAC), polyphenol content (DTPC), and flavonoid content (DTFC). Dietary antioxidant vitamins were calculated using national food composition databases. Serum TAS was 1.57 mmol/l in controls, 1.41 mmol/l in patients with newly diagnosed type 2 diabetes, and 1.23 mmol/l in patients with long-standing type 2 diabetes. Serum MDA and 4‑HAE levels were 0.78 μmol/l in controls, 1.45 μmol/l in newly diagnosed diabetes, and 1.74 μmol/l in long-standing diabetes. GPx and SOD activities were 42.6 and 1340 units/g hemoglobin (Hb), respectively, in controls, 47.3 and 2373 units/g Hb in long-standing diabetes, and 58.2 and 3093 units/g Hb in newly diagnosed diabetes. DTAC, DTPC, DTFC, and vitamin C content were 5697 μmol Trolox equivalents (TE), 1031 mg gallic acid equivalents (GAE), 223 mg quercetine equivalents (QE), and 82 mg, respectively, in control diet. In patients with long-standing diabetes, the values were 4271 μmol TE, 822 mg GAE, 173 mg QE, and 63 mg, respectively, and in those with newly diagnosed type 2 diabetes, they were 4545 μmol TE, 839 mg GAE, 180 mg QE, and 65 mg, respectively. The diet of type 2 diabetes patients is poor in antioxidants despite increased demand.