Antioxidant activity of propolis in vivo. Activity of superoxide-dismutase (SOD) (U/g Hb) during the study: a) in the men test group and b) in the women test group. Data are expressed as means ± S.D.; B (1) represents the baseline on the 15th day prior to the study and PS (30) represents propolis supplementation on the 30th day. The symbol (*) denotes statistically significant change .