The present invention relates to non-toxic composition containing, as active compounds, one or more aldehyde-binding compounds, such as L- or D-cysteine, N-acetyl cysteine, and the pharmaceutically acceptable salts thereof, and optionally one or more further active compounds selected from sulphites and xylitol, the composition being used for decreasing the risk of a subject contracting cancer of the stomach, and indirectly of the small intestine and the large intestine. The composition is formulated into a controlled-release formulation consisting of granules contained in a capsule.