British Journal of Nutrition

Human and Clinical Nutrition

Enriched cereal bars are more effective in increasing plasma quercetin compared with quercetin from powder-filled hard capsules

Sarah Egerta1a2 c1, Siegfried Wolfframa3, Beate Schulzea4, Peter Langgutha5, Eva Maria Hubbermanna4, Karin Schwarza4, Berit Adolphia6, Anja Bosy-Westphala2, Gerald Rimbacha7 and Manfred James Müllera2

a1 Department of Nutrition and Food Science, Nutritional Physiology, University of Bonn, Endenicher Allee 11-13, 53115 Bonn, Germany

a2 Department of Human Nutrition, Institute of Human Nutrition and Food Science, Christian-Albrechts-University Kiel, Kiel, Germany

a3 Institute of Animal Nutrition and Physiology, Christian-Albrechts-University Kiel, Kiel, Germany

a4 Department of Food Technology, Institute of Human Nutrition and Food Science, Christian-Albrechts-University Kiel, Kiel, Germany

a5 Department of Biopharmaceutics and Pharmaceutical Technology, Institute of Pharmacy, Johannes Gutenberg-University, Mainz, Germany

a6 Schwartauer-Werke GmbH & Co. KGaA, Bad Schwartau, Germany

a7 Department of Food Science, Institute of Human Nutrition and Food Science, Christian-Albrechts-University Kiel, Kiel, Germany

Abstract

The flavonol quercetin, is one of the major flavonoids found in edible plants. The bioavailability of quercetin in humans may be influenced by the food matrix in which it is consumed as well as by its chemical and physical form. The objective of the present study was to investigate the biokinetics of quercetin from quercetin-enriched cereal bars and quercetin powder-filled hard capsules. In a randomised, single-blinded, diet-controlled cross-over study, six healthy women aged 22–28 years took a single oral dose of approximately 130 mg quercetin equivalents from either quercetin-enriched cereal bars (containing 93·3 % quercetin aglycone plus 6·7 % quercetin-4′-glucoside) or quercetin powder-filled hard capsules (100 % quercetin aglycone). Blood samples were drawn before and after quercetin administration over a 24 h period. The concentrations of quercetin and its monomethylated derivatives, isorhamnetin (3′-O-methyl quercetin) and tamarixetin (4′-O-methyl quercetin), were measured by HPLC with fluorescence detection after plasma enzymatic treatment. The systemic availability as determined by comparing the plasma concentration–time curves of quercetin was found to be five times and the cmax values six times higher after ingestion of 130 mg quercetin by quercetin-enriched cereal bars than after ingestion by quercetin capsules. In contrast, tmax did not differ significantly between the two treatments. The cmax values for isorhamnetin and tamarixetin were four and nine times higher after ingestion of quercetin by quercetin-enriched cereal bars than after ingestion by quercetin capsules. In conclusion, quercetin from quercetin-enriched cereal bars is significantly more bioavailable than from quercetin powder-filled hard capsules.

(Received February 09 2011)

(Revised May 10 2011)

(Accepted May 13 2011)

(Online publication July 20 2011)

Correspondence:

c1 Corresponding author: S. Egert, fax +49 228 733217, email s.egert@uni-bonn.de

Footnotes

Abbreviations: AUC, area under plasma concentration–time curve; cmax, maximum plasma concentration; tmax, time between oral administration of quercetin and the appearance of cmax

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