GSTM1 and colorectal carcinoma: In the prospective population-based Singapore Chinese Health Study including 231 incident CRC cases and 1194 controls, a risk reduction of 69% was found by high intake of isothiocyanates among homozygous GSTM1 and GSTT1 null allele carriers vs. no risk reduction among wildtype allele carriers.26 These results could indicate that isothiocyanates from cruciferous vegetables protect against CRC in individuals with low GST activity.26