E250 or sodium nitrite is a synthetic additive used in meat products. Its consumation leads to many disorders including the cancer of large intestine. Our goal was to find out the concetration of E250 in meat products and its effect on blood cells. We examined 20 samples. Average concentration of nitrites was 1.6 mg/kg (in drinking water it is approx. 0.3 mg/l). We applied this amount into the five samples of human blood and using blood cells´ analyser we observed the rapid decrease of leukocytes, erythrocytes and platelets as well as the changes in hemoglobin and hematocryt. We proved that the amount of sodium nitrite used in meat products is harmful and in case of regular consumation it can affect the amount of hemoglobin in blood cells and therefore the transport of respiratory gases.