Measurement of antioxidant capacity using the biological antioxidant potential test and its role as a predictive marker of metabolic syndrome

Abstract

Background/aims: Oxidative stress increases the risk of cardiovascular complications of metabolic syndrome (MetS). This study was conducted to examine the difference in antioxidant capacity according to the presence of MetS, and to characterize the association between antioxidant capacity and MetS-related factors.

Methods: We used the biological antioxidant potential (BAP) test to estimate antioxidant capacity. The BAP test has recently been used as an indicator of antioxidant capacity. We measured BAP levels in 45 patients with MetS (mean age, 44.6 ± 1.1 years) and 47 age- and sex-matched controls (mean age, 42.7 ± 1.1 years). To evaluate the association between antioxidant capacity and MetS, adiponectin, high-sensitivity C-reactive protein (hs-CRP), interleukin-6, tumor necrosis factor-α, and homeostatic model assessment for insulin resistance (HOMA-IR), linear regression and logistic analyses were performed.

Results: The mean BAP of the MetS group (1,937.3 ± 36.5 µmol/L) was significantly lower than that of the non-MetS group (2,101.7 ± 29.5 µmol/L). Also, the mean BAP was low in persons having low high density lipoprotein and high triglyceride. Reduced antioxidant capacity was significantly associated with adiponectin, HOMA-IR and hs-CRP after adjusting for age and sex. The odds ratios for MetS with BAP, log adiponectin, log HOMA-IR, and log hs-CRP were 0.63 (95% confidence interval [CI], 0.49 to 0.82), 0.22 (0.10 to 0.51), 14.24 (4.35 to 46.58), and 1.93 (1.36 to 2.75), respectively.

Conclusions: Persons with MetS showed reduced antioxidant capacity. We identified relationships between antioxidant capacity measured by BAP test and MetS, as well as MetS-related factors, such as insulin resistance, hs-CRP, and adiponectin.

Keywords: Adiponectin; Insulin; Metabolic syndrome; Oxidative stress.

Figure 1

Antioxidant capacity in metabolic syndrome (MetS) and its components. Reduced antioxidant capacity is defined as mean biological antioxidant potential (BAP) < 2,000 µmol/L. The BAP levels were significantly lower than reference value in low high density lipoprotein (HDL), high triglyceride (TG), and presence of MetS groups. Abdominal obesity, waist circumference of ≥ 90 cm in men or ≥ 85 cm in women; high blood pressure (BP), systolic blood pressure of ≥ 130 mmHg, diastolic blood pressure of ≥ 85 mmHg; low HDL, serum HDL cholesterol concentration of < 40 mg/dL in men or < 50 mg/dL in women; high fasting blood glucose (FBG), serum glucose concentration of ≥ 100 mg/dL; high TG, serum TG concentration of ≥ 150 mg/dL. BAP level is shown as the geometric mean. The t test or chi-square test was used to compare the groups. ^ap < 0.05, ^bp < 0.001.

Figure 2

Comparison of insulin, homeostatic model assessment for insulin resistance (HOMA-IR), adiponectin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and high-sensitivity C-reactive protein (hs-CRP) levels according to antioxidant capacity. (A, B, D-F) The insulin, HOMA-IR, IL-6, TNF-α, and hs-CRP levels were higher and (C) adiponectin level was lower in the reduced antioxidant capacity group than those in the normal antioxidant capacity group. This graph compares the mean ± standard error of each factor between the two groups. ^ap < 0.05.