Obesity is associated with decreased total antioxidant capacity in apparently healthy postmenopausal women

Objectives: Postmenopausal period is associated with the decline in antioxidant levels due to gradual loss of estrogen, increased body weight and central adiposity. The present study aimed to evaluate association of adiposity and regional fat distribution with total antioxidant capacity in postmenopausal women. Methods: This cross-sectional study included 90 apparently healthy postmenopausal women. We measured anthropometric indices including body mass index (BMI), waist circumference (WC) and waist-hip ratio (W/H ratio). Total fat mass (TFM), total lean mass (TLM), percentage fat mass (%FM), visceral fat diameter (VFD) and subcutaneous fat diameter (SFD) were measured using ultrasound. Serum total antioxidant capacity (TAC) was measured by quantitative colorimetric determination using Total antioxidant Capacity -QuantiCromAntioxidant Assay Kit (BioAssay systems, USA; DTAC-100). Results: Out of 90 postmenopausal women, 35.9% were overweight and 25.0% obese, while 60.9% had central obesity. Postmenopausal obese women had significantly lower median TAC level [308.3 (283.0-375.1)] mM Trolox equivalents compared to overweight [383.38 (356.5-389.4) mM Trolox equivalents; p<0.001] and normal weight women [376.3 (318.0-388.7) mM Trolox equivalents; p<0.005]. Serum logTAC level was inversely associated with BMI, TFM, TLM and WC in postmenopausal women. However, when stratified by central obesity, inverse associations between serum logTAC level and BMI (r=-0.503; p<0.001), TFM (r=-0.383, p=0.004) and WC (r=-0.408; p=0.002) were observed only in postmenopausal women with central obesity. Conclusion: Our results provide evidence that obesity and central obesity during postmenopausal period are associated with decreased total antioxidant capacity and depleted antioxidant defenses possibly due to elevated oxidative stress. Larger prospective studies are needed to evaluate whether obese postmenopausal women might benefit from antioxidants supplementation for the prevention of obesity related diseases. Keywords: total antioxidant capacity, oxidative stress, obesity, overweight