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Plasma metabolites of dietary flavonoids after combination meal consumption with onion and tofu in humans
Author(s) -
Nakamura Toshiyuki,
Murota Kaeko,
Kumamoto Shun,
Misumi Kazuhiro,
Bando Noriko,
Ikushiro Shinichi,
Takahashi Nobuyuki,
Sekido Keiko,
Kato Yoji,
Terao Junji
Publication year - 2014
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.201300234
Subject(s) - quercetin , postprandial , genistein , isoflavones , chemistry , bioavailability , food science , daidzein , metabolism , flavonoid , equol , meal , biochemistry , endocrinology , pharmacology , biology , insulin , antioxidant
Scope The effect of food combination on metabolic profile in postprandial plasma has hardly been reported. We investigated the absorption and metabolism of quercetin and soy isoflavones in humans after combination meal consumption. Methods and results Five healthy volunteers ingested sautéed onion and tofu, and the plasma metabolites of quercetin and isoflavones were analyzed. Quercetin and genistein were incubated with human intestinal C aco‐2 cells and human hepatoma H ep G 2 cells to further analyze the influence of simultaneous supply to the small intestine and the liver. Glucuronosyl conjugates of quercetin and methylated quercetin were the major plasma metabolites in the case of onion intake. Plasma metabolites with the single serving of tofu were both glucuronide and sulfate metabolites of isoflavones. Interestingly, quercetin sulfate was only detected after the combined intake of sautéed onion and tofu, accompanied with a decrease in sulfated isoflavones. Besides, quercetin was shown as the preferential substance for phase II enzymes over genistein in both C aco‐2 and H ep G 2 cells. Conclusion These results indicate that, when flavonoids and isoflavonoids were ingested together, the metabolic conversions in the small intestine and/or the liver could be altered, resulting in the variation of the postprandial profiles of the plasma metabolites.