Background. Organism’s lipid peroxidation is one of the most often examined and known physiological process evoked by free radicals. It concerns oxidation reaction of unsaturated fatty acid and/or other lipids leading to lipid oxidation products (LOP), which as a result of further changes generate among others the malondialdehyde molecules. The aim of the work was an estimation if raw or cooked kale addition to rat’s diet infl uences antioxidant defense effi ciency in their organisms in comparison to rats fed with standard AIN-93G diet.

Material and methods. The experiment was conducted with 36 Wistar strain, male rats over 21 days. The rats were divided into 3 groups (each 12 stuck) which were fed with: standard diet AIN-93G (2 groups), AIN-93G diet with 10% addition of raw kale (2 groups), and AIN-93G with 10% addition of cooked lyophilised kale. The total content of polyphenols (FC method) and antioxidant activity (ABTS+•) were previously determined in raw and then in cooked kale. On the 20th day of experiment, half of rats (6 stuck) of each kind of the diet were injected intraperitoneally by the solution of paraquat (PQ) in physiological salt to evoke the oxidative stress. The next day animals were stunned and blood from their hearts was sampled. In the obtained serum, the levels of lipid oxidation products (LOP) and malondialdehyde (MDA) were assessed.

Results. It was observed that in blood serum of rats fed with modifi ed diet with raw and cooked lyophilised kale addition the lipid oxides level was lower in comparison to control group fed with standard diet (p < 0.05). It was found that intoxication with paraquat caused growth of MDA and LOP levels in blood serum of all rats in comparison to not intoxicated groups but that growth was the lowest in group fed diet with cooked kale addition.

Conclusion. Diet with kale, both raw and cooked, effi ciently inhibited the lipid peroxidation process in rats’ organisms, ongoing during natural metabolism and during evoked oxidative stress.