In the present work it was evaluated to what degree the selected fractions of dietary fibre, i.e. cellulose, lignin and high-methylated pectins with the metyla- tion degree of 56 or 73%, influence the determination of sodium nitrite added to in vitro gastric juice with the pH from 2.0 to 3.5. High-methylated pectin was the fraction of dietary fibre which was found to decrease the amount of sodium nitrite. Cellulose and lignin did not lower the content of sodium nitrite in the conditions of gastric juice.