Quercetin is a strong antioxidant and a major dietary flavonoid. Epidemiological studies suggest that consumption of quercetin protects against cardiovascular disease, but its absorption in man is controversial. We fed nine subjects a single large dose of onions, which contain glucose conjugates of quercetin, apples, which contain both glucose and non-glucose quercetin glycosides, or pure quercetin-3-rutinoside, the major quercetin glycoside in tea. Plasma levels were then measured over 36 h. Bioavailability of quercetin from apples and of pure quercetin rutinoside was both 30% relative to onions. Peak levels were achieved less than 0.7 h after ingestion of onions, 2.5 h after apples and 9 h after the rutinoside. Half-lives of elimination were 28 h for onions and 23 h for apples. We conclude that conjugation with glucose enhances absorption from the small gut. Because of the long half-lives of elimination, repeated consumption of quercetin-containing foods will cause accumulation of quercetin in blood.© 1997 Federation of European Biochemical Societies.Key words: Flavonoid glycoside; Dietary quercetin; Bioavailability; Pharmacokinetics; Human pounds, which are called glycosides in general, or more specifically glucosides, rutinosides, or xylosides depending on their sugar moiety. The sugar-flavonol bond is a (3-glycosidic bond which is resistant to hydrolysis by pancreatic enzymes. It was thought that such glycosides cannot be absorbed [1]. However, when we measured faecal quercetin in ileostomy subjects we found that human absorption of quercetin-p-glucosides from onions was 52%, whereas absorption of quercetin without its sugar moiety, the so-called aglycone, and of quercetin-|3-rutinoside were both only about 20% [12]. These data suggest that the sugar moiety of quercetin glycosides affects their absorption. In the present study we determined the bioavailability and other pharmacokinetic parameters of various quercetin glycosides contained in foods. Subjects ingested onions, apples and pure quercetin rutinoside (rutin), the major quercetin compound found in tea [13]. Onions contain mainly glucose glycosides of quercetin [14,15]. Apples contain a variety of quercetin glycosides, including galactosides, arabinosides, rhamnosides, xylosides, and glucosides ( Fig. 1) [16][17][18]. Preliminary pharmacokinetic data on onions have been published [19].

Objective: To evaluate the effect of moderate alcohol consumption on the acute phase proteins C-reactive protein and fibrinogen. Design: Randomized, diet-controlled, cross-over study. Setting: The study was performed at TNO Nutrition and Food Research, Zeist, The Netherlands. Subjects: Ten middle-aged men and 10 postmenopausal women, all apparently healthy, non-smoking and moderate alcohol drinkers, were included. One women dropped out because of a treatment-unrelated cause. The remaining 19 subjects finished the experiment successfully. Interventions: Men consumed four glasses and women consumed three glasses of beer or no-alcohol beer (control) with evening dinner during two successive periods of 3 weeks. The total diet was supplied to the subjects and had essentially the same composition during these 6 weeks. Before each treatment there was a 1 week washout period to compensate for possible carry-over effects. Results: Plasma C-reactive protein and fibrinogen levels were decreased by 35% (P ¼ 0.02) and 12.4% (P 0.001), respectively, after 3 weeks' consumption of beer, as compared to no-alcohol beer consumption. Conclusions: Moderate alcohol consumption significantly decreased plasma C-reactive protein and fibrinogen levels. An antiinflammatory action of alcohol may help explain the link between moderate alcohol consumption and lower cardiovascular disease risk.

No abstract

No abstract

Background: Moderate alcohol consumption is inversely associated with cardiovascular diseases. Changes in hormone levels might in part help explain the positive health effect. This study was performed to examine the effect of moderate alcohol consumption on plasma dehydroepiandrosterone sulfate (DHEAS), testosterone, and estradiol levels.Methods: In a randomized, diet-controlled, crossover study, 10 middle-aged men and 9 postmenopausal women, all apparently healthy, nonsmoking, and moderate alcohol drinkers, consumed beer or no-alcohol beer with dinner during two successive periods of 3 weeks. During the beer period, alcohol intake equaled 40 and 30 g per day for men and women, respectively. The total diet was supplied and had essentially the same composition during these 6 weeks. Before each treatment there was a 1 week washout period, in which the subjects were not allowed to drink alcoholic beverages. At the end of each of the two experimental periods, fasting blood samples were collected in the morning.Results: Moderate alcohol consumption increased plasma DHEAS level by 16.5% (95% confidence interval, 8.0 -24.9), with similar changes for men and women. Plasma testosterone level decreased in men by 6.8% (95% confidence interval, Ϫ1.0 -Ϫ12.5), but no effect was found in women. Plasma estradiol level was not affected. Serum high-density lipoprotein cholesterol level increased by 11.7% (95% confidence interval, 7.3-16.0), with similar changes for men and women. The overall alcohol-induced relative changes in DHEAS, testosterone, and estradiol correlated positively with the relative increase in high-density lipoprotein cholesterol (adjusted for the relative change in body weight); however, findings were only borderline significant for DHEAS and estradiol (r ϭ 0.44, p ϭ 0.08; r ϭ 0.32, p ϭ 0.21; and r ϭ 0.46, p ϭ 0.06, respectively).Conclusions: A protective effect of moderate alcohol consumption for cardiovascular disease risk may in part be explained by increased plasma DHEAS level.