The present invention relates to a non-toxic composition containing one or more cysteine compounds selected from L-or D-cysteine, N-acetyl cysteine for decreasing the risk of a subject contracting cancer of the mouth and of the stomach, by locally binding both oxygen radicals and aldehydes present in the mouth and in the stomach, the composition being formulated with the help of two or more additives into a layered mixture, added into capsules or tablets, whereby these units contain one or more inner controlled release layers.
