Christine Dalga ˚rd Lene Christiansen Torbjo ¨rn Jonung Michael I. Mackness Moniek P.M. de Maat Mogens Hørder No influence of increased intake of orange and blackcurrant juices and dietary amounts of vitamin E on paraoxonase-1 activity in patients with peripheral arterial disease Received: 21 December 2006 Accepted: 24 July 2007 Published online: 21 August 2007 j Abstract Background Parao- xonase-1 (PON1) is an antioxida- tive enzyme associated with HDL and its serum activity is associated with risk of cardiovascular disease. The interindividual variation in PON1 activity is partly determined by genetic factors, such as poly- morphisms in the PON1 gene, but also by dietary factors like the antioxidants. Aim of the study We examined the effect of antioxi- dant-rich orange and blackcurrant juices and vitamin E supplement on PON1 activity in patients with peripheral arterial disease. Fur- thermore, we studied whether genetic polymorphisms in the PON1 gene predicted the change in PON1 activity. Methods The study was designed as a cross-over trial with 48 participants who received two of the four possible treatments: (1) 250 ml orange juice and 250 ml blackcurrant juice; (2) 15 mg vitamin E; (3) 250 ml orange juice and 250 ml blackcurrant juice and 15 mg vitamin E; or (4) control/placebo (energy-equivalent sugar-contain- ing beverage). The treatments were given for 28 days, separated by a 4-week wash-out period. Results The PON1 activity was not affected by juice or vitamin E supplement neither was there evi- dence of synergetic effects. How- ever, a statistically significant interaction was observed between treatment and PON1 genotype, such that PON1 activity increased after juice alone in patients carry- ing the PON1 L55-allele. Results need to be interpreted with care since the study population was relatively small. Conclusion Con- sumption of orange and black- currant juice and vitamin E supplement does not affect the activity of PON1 in patients with peripheral arterial disease. How- ever, a gene-diet interaction may be present. j Key words PON1–orange juice–blackcurrant juice–vitamin E–oxidative stress–F 2 -isoprostanes ORIGINAL CONTRIBUTION Eur J Nutr (2007) 46:354–363 DOI 10.1007/s00394-007-0675-6 EJN 675 C. Dalga ˚rd (&) Institute of Public Health, Environmental Medicine, University of Southern Denmark J.B. Winsløwsvej 17, 2nd floor 5000 Odense C, Denmark E-Mail: cdalgaard@health.sdu.dk L. Christiansen Æ M. Hørder Dept. of Biochemistry, Pharmacology and Genetics, Odense University Hospital Odense, Denmark L. Christiansen Institute of Public Health-Epidemiology University of Southern Denmark Odense, Denmark T. Jonung Dept. of Vascular Surgery Ribe County Hospital Esbjerg, Denmark T. Jonung (Present address) Institute of Surgical Sciences University of Bergen Bergen, Norway M.I. Mackness University Dept. of Medicine Manchester Royal Infirmary Manchester, UK M.P.M. de Maat Dept. of Thrombosis Research University of Southern Denmark Esbjerg, Denmark M.P.M. de Maat Dept. of Hematology Erasmus MC Rotterdam, The Netherlands