Modulation of plasma antioxidant levels, glutathione S-transferase activity and DNA damage in smokers following a single portion of broccoli: a pilot study

BACKGROUND: Broccoli is a rich source of bioactive compounds (i.e. glucosinolates, carotenoids, vitamin C and folate) that may exert an antioxidant effect and reduce oxidative damage. The objective of this pilot study was to investigate the effect of broccoli consumption on carotenoids, vitamin C and folate absorption, glutathione S-transferase (GST) activity, and oxidatively induced DNA damage in male smokers. METHODS: Ten healthy subjects consumed a single portion of steamed broccoli (250 g) with cooked pasta. Blood was drawn at baseline and at 3, 6 and 24 h from consumption. RESULTS: Broccoli significantly (P≤0.01) increased plasma level of vitamin C and folate (+35% and 70%, respectively) at 3 h, and β-carotene (+8%) at 6 h. A modulation of GST activity occurred in plasma 6 h after broccoli consumption. A significant(P≤0.01) reduction of the levels of H2O2-induced DNA damage (−18%) was observed in blood mononuclear cells 24 h after broccoli intake in GSTM1 positive, but not in GSTM1 null subjects. CONCLUSION: One portion of broccoli increased plasma antioxidant levels, modulated plasma GST activity and improved cell resistance against H2O2-induced DNA damage in healthy smokers. These results support the importance of consuming fruit and vegetable regularly.