A vegetable/fruit concentrate with high antioxidant capacity has no effecton biomarkers of antioxidant status in male smokers

The potential benefits of a high fruit and vegetable intake on the antioxid ant status and on relevant biomarkers of oxidative damage to lipids, protei ns and DNA and on (functional) markers of oxidative stress were evaluated. A randomized, free living, open placebo-controlled cross-over trial of 3 wk , with a 2-wk washout period between treatments, was performed in a group o f 22 male smokers with a relatively low vegetable and fruit intake using a vegetable burger and fruit drink. The vegetable burger and fruit drink incr eased serum levels of vitamin C, alpha -carotene, beta -carotene, beta -cry ptoxanthin and zeaxanthin and plasma total antioxidant capacity. However, n o effects were demonstrated on any marker of oxidative damage to lipids (ma londialdehyde F-2-isoprostane) proteins (carbonyls) and DNA (Comet assay) a nd (functional) markers of oxidative stress (reduced/oxidized glutathione r atio, glutathione-S-transferase alpha, glutathione-S-transferase pi and nuc lear transcription factor-kappaB). Apparently, these increased levels of an tioxidants in serum were not sufficiently high to show beneficial changes w ith the selected biomarkers. Alternatively, oxidative stress in male smoker s with a relatively low fruit and vegetable intake might have been still to o low to demonstrate a beneficial effect of antioxidants.