Phytosterols as Functional Food Cornponents and Nutraceut icals
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Paresh C. Dutta Swedish University of Agric...
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Phytosterols as Functional Food Cornponents and Nutraceut icals
edited by
Paresh C. Dutta Swedish University of Agricultural Sciences, SLU Uppsala, Sweden
MARCEL
MARCELDEKKER, INC. DEKKER
NEWYORK BASEL
Although great care has been taken to provide accurate and current information, neither the author(s) nor the publisher, nor anyone else associated with this publication, shall be liable for any loss, damage, or liability directly or indirectly caused or alleged to be caused by this book. The material contained herein is not intended to provide specific advice or recommendations for any specific situation. Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress. ISBN: 0-8247-4750-X This book is printed on acid-free paper. Headquarters Marcel Dekker, Inc., 270 Madison Avenue, New York, NY 10016, U.S.A. tel: 212-696-9000; fax: 212-685-4540 Distribution and Customer Service Marcel Dekker, Inc., Cimarron Road, Monticello, New York 12701, U.S.A. tel: 800-228-1160; fax: 845-796-1772 Eastern Hemisphere Distribution Marcel Dekker AG, Hutgasse 4, Postfach 812, CH-4001 Basel, Switzerland tel: 41-61-260-6300; fax: 41-61-260-6333 World Wide Web http://www.dekker.com The publisher offers discounts on this book when ordered in bulk quantities. For more information, write to Special Sales/Professional Marketing at the headquarters address above. Copyright n 2004 by Marcel Dekker, Inc. All Rights Reserved. Neither this book nor any part may be reproduced or transmitted in any form by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher. Current printing (last digit): 10 9 8 7 6 5 4 3 2 1 PRINTED IN THE UNITED STATES OF AMERICA
NUTRACEUTICAL SCIENCE AND TECHNOLOGY Series Editor FEREIDOON SHAHIDI, PH.D.,FACS, FCIC, FCIFST, FRSC University Research Professor Department of Biochemistry Memorial University of Newfoundland St. John’s, Newfoundland, Canada
1. Phytosterols as Functional Food Components and Nutraceuticals, edited by Paresh C. Dutta
ADDITIONAL VOLUMES IN PREPARATION
Biotechnology for Performance Foods, Functional Foods, and Nutraceuticals, edited by Jean-Richard Neeser and Bruce J. German
Series Introduction
The Nutraceutical Science and Technology series provides a comprehensive and authoritative source of the most recent information for those interested in the field of nutraceuticals and functional foods. There is a growing body of knowledge, sometimes arising from epidemiological studies and often substantiated by preclinical and clinical studies, demonstrating the relationship between diet and health status. Many of the bioactives present in foods, both from plant and animal sources, have shown to be effective in disease prevention and health promotion. The emerging findings in the nutrigenomics and proteomics areas further reflect the importance of diet in a deeper sense, and this, together with the increasing burden of prescription drugs in treatment of chronic diseases such as cardiovascular ailments, certain types of cancer, diabetes, and a variety of inflammatory diseases, have all pushed interest in functional foods and nutraceuticals to a new high. The interest is quite widespread from producers to consumers, regulatory agencies, and health professionals. In this series, particular attention is paid to provide the most recent and emerging information on a range of topics covering the chemistry, biochemistry, epidemiology, nutrigenomics and proteomics, engineering, formulation, and processing technologies related to nutraceuticals, functional foods, and dietary supplements. Quality management, safety, and toxicology, as well as disease prevention and health promotion aspects of products of interest, are addressed. The series also covers relevant aspects related to preclinical and clinical trials as well as regulatory and labeling issues. This series provides much needed information on a variety of topics. It addresses the needs of professionals, students, and practitioners in the fields iii
iv
Introduction
of food science, nutrition, pharmacy, and health, as well as leads conscious consumers to the scientific origin of health-promoting substances in foods, nutraceuticals, and dietary supplements. Each volume covers a specific topic of related foods or prevention of certain types of diseases, including the process of aging. Fereidoon Shahidi
Preface
Phytosterols (plant sterols) have been known to lower chloesterol levels in humans since the 1950s, a finding that has resulted in the development of various food products enriched with these compounds. Widespread consumption of such food products, popularly known as functional foods, would decrease blood cholesterol levels and consequently decrease the occurrence of coronary heart diesase in certain populations in Western societies. Volumes of data have been accumulated in the area of foods enriched with phytosterols. This comprehensive volume covers a wide range of issues related to plant sterols, including occurrence, analysis, biological effects, currently available functional foods containing phytosterols, and the prospects of increasing phytosterol levels in plants. This book presents extensive literature reviews on the cholesterol-lowering properties and safety aspects of phytosterols as functional food ingredients. There are other possible biological effects of phytosterols. Cancer is another major cause of death in Western societies, and increasing evidence suggests that phytosterols may have effects on the development of this disease. Research on the role of phytosterols in cancer prevention is at quite an early stage, and increasing research in this area is expected. Chapter 5 discusses recent developments in the area of phytosterols and cancer. Research on the formation and biological effects of cholesterol oxidation products in foods and in biological samples is plentiful. However, similar research on phytosterol oxidation products has been downplayed until now for various reasons, e.g., the argument of low levels of phytosterol absorption in humans. Recent developments in the areas of occurrence, analysis, and the biological effects of phytosterol oxidation products are also highlighted in this v
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Preface
book. Based on the present knowledge of various aspects of phytosterols, it can be confidently anticipated that these interesting natural compounds are going to play a positive role in improving public health around the world. Research in the areas of other potential biological funtions of phytosterols is expected to increase in the future. As the editor of this book, I would like to express my profound gratitude to all the contributors for taking some of their valuable time to complete this volume. Unlimited and very helpful support from the staff members of Marcel Dekker, Inc., is also gratefully acknowledged. Paresh C. Dutta
Contents
Series Introduction Preface Contributors
Fereidoon Shahidi
1. Occurrence and Levels of Phytosterols in Foods Vieno Piironen and Anna-Maija Lampi
iii v ix 1
2. Analysis of Phytosterols in Foods Anna-Maija Lampi, Vieno Piironen, and Jari Toivo
33
3. Plant Sterol Analysis in Relation to Functional Foods Guus S. M. J. E. Duchateau, Hans-Gerd M. Janssen, and Arjan J. H. Louter
75
4. Analysis of Phytosterols in Biological Samples Arnis Kuksis 5. Does Phytosterol Intake Affect the Development of Cancer? Lena Norme´n and Susan W. Andersson 6. Role of Plant Sterols in Cholesterol Lowering Lena Norme´n, Jiri Frohlich, and Elke Trautwein
133
191
243
vii
viii
Contents
7.
Plant Sterols in Functional Foods Robert A. Moreau
8.
Safety of Phytosterols and Phytosterol Esters as Functional Food Components David Kritchevsky
347
Potential Health Risks Associated with Large Intakes of Plant Sterols W. M. Nimal Ratnayake and Elizabeth J. Vavasour
365
Chemistry, Analysis, and Occurrence of Phytosterol Oxidation Products in Foods Paresh C. Dutta
397
Biological Effects and Safety Aspects of Phytosterol Oxides Lisa Oehrl Dean and Leon C. Boyd
419
Prospects of Increasing Nutritional Phytosterol Levels in Plants Tatu A. Miettinen and Helena Gylling
431
9.
10.
11.
12.
Index
317
441
Contributors
Susan W. Andersson Department of Clinical Nutrition, Sahlgrenska Academy at Go¨teborg University, Go¨teborg, Sweden Leon C. Boyd Department of Food Science, North Carolina State University, Raleigh, North Carolina, U.S.A. Guus S. M. J. E. Duchateau Unilever Health Institute, Unilever Research and Development, Vlaardingen, The Netherlands Paresh C. Dutta Department of Food Science, Swedish University of Agricultural Sciences, SLU, Uppsala, Sweden Jiri Frohlich Healthy Heart Program, University of British Columbia, Vancouver, British Columbia, Canada Helena Gylling University of Kuopio, and Kuopio University Hospital, Kuopio, Finland Hans-Gerd M. Janssen The Netherlands David Kritchevsky Arnis Kuksis
Unilever Research and Development, Vlaardingen,
The Wistar Institute, Philadelphia, Pennsylvania, U.S.A.
University of Toronto, Toronto, Ontario, Canada ix
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Contributors
Anna-Maija Lampi Department of Applied Chemistry and Microbiology, University of Helsinki, Helsinki, Finland Arjan J. H. Louter Netherlands
Unilever Research and Development, Vlaardingen, The
Tatu A. Miettinen Finland
Biomedicum Helsinki, University of Helsinki, Helsinki,
Robert A. Moreau Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, Pennsylvania, U.S.A. Lena Norme´n Healthy Heart Program, University of British Columbia, Vancouver, British Columbia, Canada Lisa Oehrl Dean Department of Food Science, North Carolina State University, Raleigh, North Carolina, U.S.A. Vieno Piironen Department of Applied Chemistry and Microbiology, University of Helsinki, Helsinki, Finland W. M. Nimal Ratnayake Food Directorate, Nutrition Research Division, Health Canada, Ottawa, Ontario, Canada Jari Toivo
National Technology Agency of Finland, Helsinki, Finland
Elke Trautwein Unilever Health Institute, Unilever Research and Development, Vlaardingen, The Netherlands Elizabeth J. Vavasour Food Directorate, Chemical Health Hazard Assessment Division, Health Canada, Ottawa, Ontario, Canada
1 Occurrence and Levels of Phytosterols in Foods Vieno Piironen and Anna-Maija Lampi University of Helsinki, Helsinki, Finland
I.
INTRODUCTION
Phytosterols are present in all plants and in foods containing plant-based raw materials. In normal diets vegetable oils and products based on them are generally acknowledged to be the richest sources of phytosterols (1,2). However, the significance of other foods, especially cereal products and vegetables, depends on dietary patterns. Some foods generally consumed only in low quantities but containing considerable amounts of sterols, such as nuts, may contribute significantly to the dietary phytosterol intakes of some individuals or population groups. On the other hand, food items with rather low levels of phytosterols but consumed as major food items may become significant sources. When various foods are evaluated as phytosterol sources, the main interest is generally in the levels of individual sterols, particularly different desmethyl sterols such as sitosterol, campesterol, stigmasterol, avenasterols, and stanols, which comprise the majority of phytosterols in normal foods (2,3). More rarely, monomethyl and dimethyl sterols are also determined. In addition to the parent sterol composition, the distribution of the various steryl conjugates is also of interest. These conjugates, i.e., esters with fatty acids (SEs), esters with phenolic acids (SPHEs), glycosides (SGs), and acylated glycosides (ASGs), may have different chemical, technological, and nutritional properties. Cholesterol often accounts for 1–2% of the total sterols in plants and may comprise 5% or more in certain plant families, 1
2
Piironen and Lampi
species, organs, or tissues (3). However, cholesterol levels of plants are not discussed further in this chapter. The serum cholesterol–lowering effect of phytosterols, when consumed at levels of 1.5–2 g/day, has led to great interest in phytosterol-enriched foods and their development. However, little is known about the effects of phytosterol intake from nonenriched foods. Phytosterols were suggested to be at least partially responsible for the differences in plasma cholesterol levels and synthesis observed when 16 normolipidemic subjects were given experimental diets with corn or olive oil (4). A˚gren et al. (5) showed that both serum total and low-density lipoprotein (LDL) cholesterol levels of patients with rheumatoid arthritis were significantly decreased by a vegan diet containing on average 732 mg/day of total phytosterols. Furthermore, Ellegard et al. (6) concluded that the effect of the current dietary recommendation to reduce saturated fat and increase dietary fiber may partly be explained by the phytosterol content of the diet. Later, Otslund (7) compared corn oil and corn oil purified free from sterols, and reported that cholesterol absorption was significantly increased when the oil was purified from phytosterols. In a case-control study of De Stefani et al. (8), there was a strong inverse relationship between the total phytosterol intake and stomach cancer; the relationship remained after control for antioxidants, such as vitamin C. On the other hand, a higher dietary intake of phytosterols was not associated with a lower risk of colon or rectal cancer in a prospective epidemiological study (9). More research is clearly needed to clarify the potential role of phytosterols in nonenriched diets. For this task, reliable food composition data based on phytosterol levels in foods are needed (9–12). Recent estimates of phytosterol intake from nonenriched foods range from 138 to 358 mg/day (9,12–16). However, lower estimates have also been published; analysis of 3-day composite diets gave intakes of 78 mg (general U.S. population), 89 mg (Seventh Day Adventists, pure vegetarians), 344 mg (Seventh Day Adventists, lacto-ovo-vegetarians), and 230 mg (Seventh Day Adventists, nonvegetarians) (17). The significance of different food groups as phytosterol sources varies in different populations. Cereal products were the main contributors (38–43%), followed by margarines and oils both in the Netherlands and in Finland (9,12). The contribution of vegetables, fruits, and berries was also significant, i.e., 20–25%. In Uruguay fruits were calculated to contribute as much as 36.4%, followed by vegetables (15.9%) and tubers (11.3%) (8). On the other hand, in the United Kingdom oils and fats were calculated to contribute 87 mg/day cereals 62 mg/day and vegetables 15 mg/day (13). Sitosterol is the main dietary phytosterol, with a reported proportion of 56–79% of the total dietary phytosterol intake (9,13,14). Campesterol and stigmasterol contributed 18% and 9% and stanols 9% to the total phytosterols (9).
Occurrence and Levels of Phytosterols in Foods
II.
3
PHYTOSTEROLS IN VEGETABLE OILS AND FATS
Vegetable oils are in general rich in free phytosterols and their fatty acid esters, although some differences between oils as dietary phytosterol sources are evident. Furthermore, effects of various processes applied in vegetable oil refining and in producing oil-based products must also be taken into account. A.
Phytosterol Contents and Compositions of Vegetable Oils
Most crude vegetable oils contain 1–5 g kg1 of total phytosterols (1,2,18). For example, crude soybean oil contains 3.0–4.4 g kg–1 of phytosterols (Table 1). Among the most commonly used oils, corn and rapeseed oils are exceptions. In recent studies, crude corn oil was reported to contain 7.8–11.1 g kg–1 and rapeseed oil 6.8–8.8 g kg–1 of total sterols (20–22) (Table 1). Earlier, corn oil was reported to contain as much as 13.9 g kg–1 of total phytosterols (1). In addition, some special oils used in lower quantities are still richer in sterols; wheat germ and corn germ oils were reported to contain 17–26 g kg–1 (1,20) and 10.7 g kg–1 of phytosterols, respectively (20). On the other hand, lower amounts of sterols are found in palm oil (0.7–0.8 g kg–1) (20,22) and coconut oil (0.7 g kg–1) (22). Refining of oils leads to somewhat lower phytosterol levels (Table 1). As an example, the recently reported total sterol contents in refined rapeseed and corn oils, available commonly for consumers, are 6.4–7.7 and 6.9–7.7 g kg–1, whereas the corresponding values for crude oils are 6.8–8.8 and 7.8– 11.1 g kg–1, as described above. Effects of different refining steps are discussed in more detail below in section C. The most important desmethyl sterol in vegetable oils is sitosterol, which in two recent comprehensive studies accounted for 38% (borage oil) to 91% (avocado oil) (24) and 51% (rapeseed oil) to 95% (walnut oil) of phytosterols (22). The range for rapeseed and soybean oils is rather similar, 51–60% (22–24,27,28) and 52–61% (22,24,28), respectively, whereas higher proportions have been reported for various olive oils, 66–89% (22–25,28– 30). Other desmethyl sterols occurring in significant amounts include stigmasterol, campesterol, and D5-avenasterol. Borage, sesame, and evening primrose oils contained substantially more D5-avenasterol than the other analyzed oils (24). The same authors also measured low concentrations of stanols (