Methods and compositions for effectively lowering the carbon-14 content, particularly of DNA and histones in vertebrates, especially humans, to significantly below normal background levels and thereby reduce chromosomal damage using nutritional or dietary supplements based on low radiocarbon DNA, amino acid and histone precursors, further preferably including those which contribute the largest share of histone carbon atoms. Administration of the supplements during the earliest and/or most active growth stages of life is particularly beneficial. Particularly useful supplements are prepared by combining low radiocarbon precursor compounds with ordinary supplement or dietary components that exhibit substantially normal background radiocarbon concentrations.
