Objectives: To evaluate the effect of the red wine phenolic compound (RWPC) dietary supplementation without alcohol interference on: (1) some of the biochemical characteristics of LDL, (2) the oxidative susceptibility of LDL and (3) the antioxidant capacity of total plasma (Pl-AOC). In order to account for discrepancies between the three series of data, the in vitro stability of the association of phenolic compounds and LDL was tested. Design: An intervention study with 20 volunteers. Each served as his own control. Cu 2 -oxidizability of LDL and Pl-AOC were tested on blood samples before and after dietary supplementation. Cu 2 -oxidizability of LDL was also tested by co-incubation in the presence of RWPC or phenolic acids with or without extensive dialysis. Setting: The Laboratory of Lipid Biochemistry and Biology, School of Medicine, and the Laboratory of Metabolic Diseases, Lapeyronie Hospital, University of Montpellier, France. Subjects: Healthy males, nonsmokers and moderate drinkers, submitted to a dietary regimen deprived of vitamin E and C for a period of 10 d before supplementation. They also abstained from alcohol, wine, fruit juices, coffee, tea and cola beverages during this period. Intervention: Six 0.33 g capsulesad (namely two capsules at each meal) of a preparation of red wine phenolic compounds in a dry powder form were given to the volunteers over a period of two weeks. Blood samples were drawn in fasting conditions at day 0 and day 14 of the supplementation period. Results: Supplementation led to: (1) in LDL, a signi®cant increase in vitamin E content (n 20, P 0.01) or vitamin Eatotal fatty acid bis-allylic carbon number ratio (n 20, P 0.006) without modi®cation in the other biochemical characteristics or Cu 2 -oxidizability; (2) in plasma, a signi®cant increase in the antioxidant capacity (n 11, P 0.01). In vitro studies showed that RWPC or sinapic, caffeic or ferulic acids incubated in the presence of LDL increased the protection of the lipoparticle against oxidation (caffeic b sinapic b ferulic). This effect, however, was totally lost after extensive dialysis. Conclusions: The enhancing effect of the RWPC supplementation on Pl-AOC may be due to a phenoliccompound action both in the aqueous phase of plasma and at the surface of lipoprotein particles. Surface location possibly explains the enhancing-sparing effect of supplementation on LDL vitamin E and the absence of effect on dialysed-LDL oxidizability.

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