Influence of Quercetin Supplementation on Disease Risk Factors in Community-Dwelling Adults

Appalachian State University, Kannapolis, NC, USA.
Journal of the American Dietetic Association (Impact Factor: 3.92). 04/2011; 111(4):542-9. DOI: 10.1016/j.jada.2011.01.013
Source: PubMed

ABSTRACT In vitro data indicate quercetin has antioxidative and anti-inflammatory functions with the potential to lower disease risk factors, but data in human beings are limited.
The objective of this study was to investigate the effect of quercetin, vitamin C, and niacin supplements (500 mg quercetin, 125 mg vitamin C, and 5 mg niacin [Q-500]; 1,000 mg quercetin, 250 mg vitamin C, and 10 mg niacin [Q-1,000]), on disease risk factors in a large group of community adults (n=1,002, 60% women) varying widely in age and body mass index.
Subjects were randomized into one of three groups (placebo, Q-500, or Q-1,000) and ingested supplements for 12 weeks. Blood samples were taken pre- and postsupplementation, and plasma quercetin, inflammatory markers (ie, C-reactive protein and five cytokines), diagnostic blood chemistries, blood pressure, and blood lipid profiles were measured.
Plasma quercetin increased in the Q-500 and Q-1,000 groups. No differences in blood chemistries were found except for a small decrease in serum creatinine and increase in glomerular filtration rate in Q-500 and Q-1,000 groups. A small decrease in mean arterial blood pressure was measured for Q-500 and Q-1,000 groups compared to placebo. A difference in serum total cholesterol was measured between Q-500 and placebo groups, and there was small decrease in high-density lipoprotein cholesterol levels in the Q-1,000 group. Change in inflammatory measures did not differ between groups except for a slight decrease in interleukin-6 for the Q-1,000 group.
Q-500 or Q-1,000 supplementation for 12 weeks had a negligible influence on disease risk factors.

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Available from: David Christopher Nieman, Feb 17, 2015
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    • "F.T. Rosa et al. 2 Despite the number of human intervention studies that have evaluated quercetin as an anti-inflammatory supplement, almost all of them did not observe beneficial effects (Table I). Thus, Knab et al. (2011) proposed a high dose of quercetin (500 and 1000 mg) associated with vitamin C and niacin, but they did not find improvements on inflammation markers. Egert et al. (2009) were also not able to demonstrate marked different responses in hs-TNF-a in overweight/obese subjects, with traits of metabolic syndrome after a 150 mg of quercetin/day (d) supplementation. "
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