Cranberry juice consumption did not alter blood or cellular antioxidant status or several biomarkers of lipid status pertinent to heart disease. Similarly, cranberry juice had no effect on basal or induced oxidative DNA damage. These results show the importance of distinguishing between the in vitro and in vivo antioxidant activities of dietary anthocyanins in relation to human health.

Objective: To assess whether consumption of 500 ml of blueberry juice or cranberry juice by healthy female subjects increased plasma phenolic content and antioxidant capacity. Design: Latin square arrangement to eliminate ordering effects. After an overnight fast, nine volunteers consumed 500 ml of blueberry juice, cranberry juice or a sucrose solution (control); each volunteer participated on three occasions one week apart, consuming one of the beverages each time. Blood samples were obtained by venipuncture at intervals up to four hours after consumption of the juices. Urine samples were also obtained four hours after consuming the juice. Results: Consumption of cranberry juice resulted in a signi®cant increase in the ability of plasma to reduce potassium nitrosodisulphonate and Fe(III)-2,4,6-Tri(2-pyridyl)-s-triazine, these measures of antioxidant capacity attaining a maximum after 60 ± 120 min. This corresponded to a 30% increase in vitamin C and a small but signi®cant increase in total phenols in plasma. Consumption of blueberry juice had no such effects. Conclusion: The increase in plasma antioxidant capacity following consumption of cranberry juice could mainly be accounted for by an increase in vitamin C rather than phenolics. This also accounted for the lack of an effect of the phenolic-rich but vitamin C-low blueberry juice. Sponsorship: Funded by the Scottish Executive Rural Affairs Department and the Danish Government.

Objective: To assess whether nutritionally-relevant changes in polyunsaturated fatty acid (PUFA) intake alter indices of oxidative stress in human volunteers Design: A split plotachange over dietary study where half the volunteers consumed a diet containing 5% PUFA (low PUFA) as food energy for 4 weeks and after a 6 week washout period consumed a 15% PUFA (high PUFA) diet for another 4 weeks. The second group of volunteers completed this protocol in reverse. Total fat, carbohydrate, protein and vitamin E contents of the diets were constant. Subjects: 10 healthy, non-smoking, male volunteers aged 32.6 AE 1.7 y Results: There was a signi®cant increase in whole blood oxidised glutathione (P`0.05), an index of oxidative stress, after consumption of the high PUFA diet. Moreover, urinary thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, signi®cantly increased (P 0.038) following consumption of the high PUFA diet and decreased (P 0.031) after consuming the low PUFA diet. However, there was no change in non speci®c plasma indices of lipid peroxidation, conjugated dienes and TBARS, nor in red cell antioxidant enzymes glutathione peroxidase, glutathione reductase, and catalase. However, superoxide dismutase signi®cantly decreased (13%, P 0.018) after consumption of the low PUFA diet. Total cholesterol increased by 13% (P 0.014) after consumption of the low PUFA diet. Conclusions: This study indicates that although increasing dietary levels of PUFA may favourably alter cholesterol pro®les, the same dietary changes may adversely affect some indices of lipid peroxidation. Care should be taken when providing dietary advice on PUFA intake and an adequate intake of antioxidants to match any increased PUFA may be important for preventing oxidative stress. Sponsorship: Ministry of Agriculture, Fisheries and Food (MAFF) and the Scottish Of®ce Agriculture, Environment, and Fisheries Department (SOAEFD)

The effect of increasing dietary intakes of polyunsaturated fatty acids (PUFAs) and vitamin E on indices of oxidative DNA damage was investigated. Twenty-one healthy male, nonsmokers aged 28.9 +/- 1.3 years participated in a free-living, split plot/change over trial in which half the volunteers consumed diets containing 5% PUFA as food energy for 4 wk and, after a 10 wk washout period, consumed a 15% PUFA diet for another 4 wk. The other volunteers followed an identical protocol, except that they consumed the 15% PUFA diet first. The diets were provided to volunteers either with or without an additional 80 mg dalpha-tocopherol acetate/day; otherwise total fat, carbohydrates, protein, and basal vitamin E contents remained unchanged. DNA damage induced by 200 microM H(2)O(2) in lymphocytes from volunteers as well as endogenous DNA damage in the form of oxidized pyrimidines, measured by alkaline single-cell gel electrophoresis (the comet assay), significantly decreased after consumption of the 5% PUFA diet (P<0.001 and P=0.01, respectively), but significantly increased after consumption of the 15% PUFA diet when alpha-tocopherol levels were in the range of 5-7 mg/day (P=0. 008 and P=0.03, respectively). These changes were abolished by an additional 80 mg dalpha-tocopherol/day. This study indicates that increasing dietary levels of PUFA to 15% may adversely affect some indices of DNA stability. However, increasing the dietary intake of vitamin E by 80 mg/day ameliorates the damaging effects of PUFA. -Jenkinson, A. McE., Collins, A. R., Duthie, S. J., Wahle, K. W. J., Duthie, G. G. The effect of increased intakes of polyunsaturated fatty acids and vitamin E on DNA damage in human lymphocytes.

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