CHAPTER ONE
Antioxidants in Food: Content,
Measurement, Significance,
Action, Cautions, Caveats, and
Research Needs
Iris F.F. Benzie
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, Siu-Wai Choi
Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Kowloon,
Hong Kong
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Corresponding author: e-mail address:
[email protected]
Contents
1.Introduction: Antioxidants in Food—Their Role and Importance 2
1.1Basic concepts of oxidation and the role of antioxidants 2
1.2Antioxidants: Types and action 3
1.3A closer look at ascorbic acid: A key antioxidant 4
1.4Human antioxidant defense and dietary influences 6
2.Measuring“Total Antioxidant Content” of Food 9
2.1Basic principles, notes on calibration, units, and confusion 9
2.2Limitations of the“total antioxidant content”approach: Cautions
and caveats 11
3.The FRAP Assay and Its Modified Form (FRASC) for Ascorbic Acid 13
3.1Basic principles 13
3.2The FRAP assay—Procedure in brief 14
3.3Application of the FRAP assay in food science 16
3.4A note on the“nonuric acid FRAP value”of blood plasma and its relevance
to nutritional science 16
3.5The modified FRAP assay (FRASC) for total antioxidant and ascorbic acid
measurement 32
4.Why Is the Antioxidant Content of Food of Interest? 33
4.1Basic concepts 33
4.2Antioxidants and health: The evidence and potential impact 34
5.Antioxidants in Food: Enigmas and Evolutionary Aspects 36
6.Mechanisms of Action: Redox Issues, Phytohormesis, and Colonic Microbiota 38
6.1Redox tone changes as a driving force for cytoprotection and the biological
sense of restricted bioavailability of dietary antioxidants: The redox-sensitive
KEAP-1–Nrf2 signaling pathway 39
6.2Colonic microflora and metabolism of food antioxidants: Moving into new
territory of the microbiome 42
Advances in Food and Nutrition Research, Volume 71 #2014 Elsevier Inc.
ISSN 1043-4526 All rights reserved.
http://dx.doi.org/10.1016/B978-0-12-800270-4.00001-8
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