Effect of Vicia faba and bran feeding on nitrosamine carcinogenesis and formation.

The goal of this work was to study the effect of the most common Egyptian food items, Vicia faba beans (VF) and bran, on the carcinogenicity of dibutylnitrosamine (DBN) precursors (dibutylamine and nitrite). Mice receiving DBN precursors showed a delayed gain in body weight as well as decreased protein level and 5-nucleotidase activity. Acid ribonuclease, alkaline phosphatase, and DNA level and rate of synthesis were significantly increased compared with corresponding controls. Hepatomas and bladder papillomas developed in 60% and 40% of mice, respectively, after nine months of treatment. On the other hand, administration of VF or bran, in addition to DBN precursors, lessened the damage caused by DBN precursors alone, except DNA level and rate of synthesis were elevated. Alkaline phosphatase was also elevated when bran was administered with DBN precursors. However, these elevations were still less than corresponding elevations in mice receiving DBN precursors alone. The incidence of hepatoma was also reduced to only 20% for both groups. Meanwhile, incidence of bladder papillomas was only 20% in mice receiving VF in addition to DBN precursors, and bladder papillomas were completely absent in mice receiving bran in addition to DBN precursors. In vitro studies were also performed to clarify the effect of VF or bran on diphenylnitrosamine (DPhNA) and its formation from its precursors (diphenylamine and nitrite). The study revealed that VF and bran have the ability to eliminate nitrite and DPhNA from the reaction media and to reduce the rate of formation of DPhNA from its precursors. This reaction depends on the concentration and form of VF or bran and the duration of the reaction. Thus it is concluded that some naturally occurring food items, such as VF and bran, could protect humans against the hazardous effect of nitrosamines and their precursors.