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Plasma metabolites of dietary flavonoids after combination meal consumption with onion and tofu in humans

Authors

  • Toshiyuki Nakamura,

    1. Department of Food Science, Graduate School of Nutrition and Bioscience, The University of Tokushima, Tokushima, Japan
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  • Kaeko Murota,

    Corresponding author
    1. Faculty of Science and Engineering, Department of Life Science, Kinki University, Osaka, Japan
    • Correspondence: Dr. Kaeko Murota, Faculty of Science and Engineering, Department of Life Science, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, 577-8502 Osaka, Japan

      E-mail: murota@life.kindai.ac.jp

      Fax: +81-6-6723-2721

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  • Shun Kumamoto,

    1. Faculty of Science and Engineering, Department of Life Science, Kinki University, Osaka, Japan
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  • Kazuhiro Misumi,

    1. Department of Food Science, Graduate School of Nutrition and Bioscience, The University of Tokushima, Tokushima, Japan
    Current affiliation:
    1. Department of Food Sciences and Nutritional Health, Kyoto Prefectural University, Kyoto, Japan
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  • Noriko Bando,

    1. Department of Food Science, Graduate School of Nutrition and Bioscience, The University of Tokushima, Tokushima, Japan
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  • Shinichi Ikushiro,

    1. Faculty of Engineering, Department of Biotechnology, Toyama Prefectural University, Imizu, Toyama, Japan
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  • Nobuyuki Takahashi,

    1. Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto, Japan
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  • Keiko Sekido,

    1. Department of Nursing Education, Graduate School of Health Sciences, The University of Tokushima, Tokushima, Japan
    Current affiliation:
    1. Kobe University Graduate School of Health Sciences, Kobe, Hyogo, Japan
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  • Yoji Kato,

    1. Graduate School of Human Science and Environment, University of Hyogo, Himeji, Hyogo, Japan
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  • Junji Terao

    1. Department of Food Science, Graduate School of Nutrition and Bioscience, The University of Tokushima, Tokushima, Japan
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Abstract

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 Caco-2 cells and human hepatoma HepG2 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 Caco-2 and HepG2 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.

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