High Fat Diet and Oxidant-Antioxidant Status of Blood 21 and decrease in the A520 related to DPPH decomposition over a 30-min incubation period was recorded. The DPPH radical-scavenging activity of the sample was measured in triplicate, and calculated according the formula: % radical scavenging activity = (the control absorption – the sample absorption/the control absorption) × 100. Statistical analysis Data are shown as means ± SEM. The ANOVA test followed by the Turkey post-hock test was used to compare the effect of high-fat diets. The Scheffe post-hock test was applied to compare the effect of the fat type and the t test was applied to compare the effect of the high-fat diet with the corresponding low-fat diet. Statistical significance was accepted at the p<0.05. Results Body mass gain and energy intake Fig. 1 presents the weight gain of rats fed low-fat and high-fat diets prepared with lard, sunflower oil (SO), and fish oil (FO), and their mean caloric intake during a six- week feeding period. Rats fed high-lard gained most weight compared to animals fed high-SO and high-FO (p<0.05 and p<0.01, respectively), and low-lard (p<0.05). They also consumed more energy from food than animals fed the other fats in high-fat diet (p<0.01). The weight gain of rats fed low-FO was significantly less at the end of the feeding period compared to rats fed the other low-fat diets (p<0.05), although they ate significantly more calories compared to low-lard fed rats (p<0.05). The final weight gain and mean energy intake of high-SO and low-SO fed rats were not significantly different from each other. Fig. 1. Table 3. The body weight gain and mean daily caloric intake of rats fed for 6 weeks with low-fat (LF) and high-fat (HF) diets containing lard, sunflower oil, or fish oil. Values are expressed as mean ± SEM (n = 10 per dietary group). Letters depict significant differ- ence p<0.05 as: a vs low-lard diet; b vs other HF diets. The effect of 6-week feeding low-fat and high-fat diets containing lard, sunflower oil, or fish oil as a fat source on reactive oxygen species (ROS) generation by circulating blood phagocytes Whole blood chemiluminescence Baseline [aU/104 WBC] Peak [aU/104 WBC] Total [aU × s/104 WBC] Lard 1.81 ± 0.14 3.21 ± 0.24 2267 ± 226 Low-fat diet Sunflower oil 1.83 ± 0.17 3.05 ± 0.19 2139 ± 88 Fish oil 2.08 ± 0.34 4.23 ± 0.46 3034 ± 358 Lard 1.16 ± 0.08† 2.44 ± 0.09† 1706 ± 68† High-fat diet Sunflower oil 2.12 ± 0.21‡ 4.26 ± 0.27†‡ 2838 ± 263†‡ Fish oil 1.70 ± 0.19 3.52 ± 0.21‡§ 2491 ± 132‡ Peak-chemiluminescence intensity (peak height in mV) after phorbol myristate acetate (PMA) addition; Total – area under the chemilumi- nescence intensity curve until returning to baseline after PMA addition (integrated value), aU – arbitrary units, WBC – white blood cells. Values are means of 5–7 samples; † p<0.05 vs the corresponding low-fat diet; ‡ p<0.01 vs high lard; § p<0.05 vs high sunflower oil. Vol. 47, No. 1, 2010