Comparison of the effect of raw and blanched-frozen broccoli on DNA damage in colonocytes

Consumption of cruciferous vegetables may protect against colorectal cancer. Cruciferous vegetables are rich in a number of bioactive constituents including polyphenols, vitamins and glucosinolates. Before consumption, cruciferous vegetables often undergo some form of processing that reduces their content of bioactive constituents and may determine whether they exert protective effects. The aim of this study was to compare the ability of raw and blanched-frozen broccoli to protect colonocytes against DNA damage, improve antioxidant status and induce xenobiotic metabolising enzymes (XME). Fifteen Landrace x Large White male pigs were divided into five age and weight matched sets (79 days, SD 3, and 34.7 kg, SD 3.9 respectively). Each set consisted of siblings to minimise genetic variation. Within each set, pigs received a cereal-based diet, unsupplemented (control) or supplemented with 600 g/d of raw or blanched-frozen broccoli for 12 d. The consumption of raw broccoli caused a significant 27% increase in DNA damage in colonocytes (P=0.03) relative to the control diet, whereas blanched-frozen broccoli had no significant effect. Both broccoli diets had no significant effect on plasma antioxidant status or hepatic and colonic XME. This study is the first to report that the consumption of raw broccoli can damage DNA in porcine colonocytes.