The Nutritional-Toxicological Conflict related to Seafood Consumption Faculty of Medicine and Health Sciences Department of Public Health The Nutritional-Toxicological Conflict related to Seafood Consumption ir. Isabelle Sioen Thesis submitted in fulfilment of the requirements for the degree of Doctor in Medical Sciences Promoters: Prof. Dr. S. De Henauw (Department of Public Health – Faculty of Medicine and Health Sciences) Prof. Dr. ir. J. Van Camp (Department of Food Safety and Food Quality – Faculty of Bioscience Engineering) Sioen, Isabelle The Nutritional-Toxicological Conflict related to Seafood Consumption PhD-thesis Ghent University – with references – with summary in Dutch Copyright © 2007, Isabelle Sioen All rights reserved. No part of this thesis may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage or retrieval system, without permission in writing from the author, or, when appropriate, from the publisher of the publications. Financial support for this PhD-work: Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT- Vlaanderen) The Belgian Science Policy through the SPSD II project CP/02/56 The food consumption data used in this PhD-work were financially supported by: The National Fund for Scientific Research/Flemish Division (Fund No G.0152.01 and Fund No 31557898), the Kellogg’s Benelux Company, Unilever Belgium, the Belgian Nutrition Information Center, and the Integrated Research Project SEAFOODplus, contract FOOD-CT- 2004-506359 (partial financing by the EU) Verschenen in de reeks monografieën van de Vakgroep Maatschappelijke Gezondheidkunde, Universiteit Gent ISBN 9789078344070 D/2007/4531/4 Printed by DCL Print & Sign | Leegstraat 15 | 9060 Zelzate | www.dclsigns.be “You shall offer something good to your body, so that the soul feels well to live in it.” Anonymous Members of the Jury Prof. Dr. S. De Henauw (promoter) Department of Public Health, Ghent University Prof. Dr. ir. J. Van Camp (promoter) Department of Food Safety and Food Quality, Ghent University Prof. Dr. J.L. Willems Department of Public Health, Ghent University Prof. Dr. G. De Backer Department of Public Health, Ghent University Prof. Dr. J.M. Kaufman Department of Internal Medicine, Ghent University Prof. Dr. J. Van de Voorde Department of General Physiology and Human Physiology and Pathophysiology, Ghent University Prof. Dr. C. Van Peteghem Department of Bio-analysis, Ghent University Prof. Dr. ir. G. Vansant Department of Public Health, Catholic University of Leuven Prof. Dr. ir. W. Verbeke Deparment of Agricultural Economics, Ghent University Dr. J.L. Volatier Direction Risk Assessment Nutrition & Food Safety, French Food Safety Agency Abbreviations %E percentage of total energy intake AA arachidonic acid AHA American Heart Association AMDR acceptable macronutrient distribution range bw body weight CEC Central Economic Council CHD coronary heart disease COT Committee on Toxicity (United Kingdom) Cons. consumers-only CVD cardiovascular disease DHA docosahexaenoic acid dl PCBs dioxin-like PCBs DPA docosapentaenoic acid DRI dietary reference intake EDR estimated diet record EFSA European Food Safety Authority EPA eicosapentaenoic acid FA fatty acid FAO Food and Agriculture Organization FCDB food composition database FCS food consumption survey FFQ food frequency questionnaire Hg mercury HIS health interview survey ICES International Council for the Exploration of the Sea IOM Institute of Medicine (United States of America) iPCBs indicator PCBs ISSFAL International Society for the Study of Fatty Acids ans Lipids JECFA Joint FAO/WHO Expert Committee on Food Additives LA linoleic acid LNA α -linolenic acid LC long chain LC n-3 PUFAs long chain omega-3 poly-unsaturated fatty acids LOD limit of detection LOQ limit of quantification MeHg methyl mercury n-3 omega-3 n-6 omega-6 PBDEs polybrominated diphenyl ethers ndl PCBs non-dioxin like PCBs PCBs polychlorinated biphenyls PCDDs polychlorinated dibenzo-p-dioxins PCDFs polychlorinated dibenzofurans PUFAs poly-unsaturated fatty acids SACN Scientific Advisory Committee on Nutrition (United Kingdom) SCO single cell oil SFA saturated fatty acid TDI tolerable daily intake TEFs toxic equivalency factors TEQ toxic equivalent totTEQ total TEQ TWI tolerable weekly intake UL tolerable upper intake level WHO World Health Organization Table of contents Chapter I. General introduction 15 Chapter II. Overall dietary PUFA intake and importance of seafood as 41 PUFA and vitamin D source Chapter III. Traceability and nutrient and contaminant content of seafood 75 on the Belgian market: elaboration of databases Chapter IV. Probabilistic intake assessment of multiple compounds as a 131 tool to quantify the nutritional-toxicological conflict related to seafood consumption Chapter V. General discussion 161 References 181 Summary 215 Samenvatting 219 Dankwoord/Acknowledgments 223 About the author 227 Publications of the author 229 Chapter I. General introduction Chapter I. General introduction Pioneer research in the nineteen sixties and seventies by Danish scientists indicated that the consumption of fish was associated with a reduced risk for heart disease in Greenland Eskimos (Bang & Dyerberg, 1980; Dyerberg et al, 1975). This Eskimo population experienced a low mortality from coronary heart disease despite a diet rich in fat and cholesterol. The investigators proposed that this could be related to the high content of omega-3 fatty acids, typically present in marine foods. These Eskimo studies have triggered a much broader and intensified research on the importance of omega-3 fatty acids and seafood in the human diet. This PhD-thesis is embedded in this research area and examines in the first place the intake of omega-3 and other fatty acids by the Flemish and Belgian population. In a next step, the question is raised whether seafood is a safe dietary source of these fatty acids and whether the consumption conform with physiological needs induces any toxicological concern. The latter is of importance since the favourable health perception is troubled by information regarding the potential adverse health impact of chemical contaminants in marine foods, occuring naturally or resulting from man-made processes. Persistent organochlorine compounds, e.g. dioxin-like substances, and organochlorine pesticides, as well as heavy metals, e.g. mercury, accumulate in the marine food chain. As a result, people consuming seafood are potentially at increased risk to ingest simultaneously compounds that can have toxicological effects. These conflicting facts form a potential base for an important public health conflict between dietary recommendations on the one hand and toxicological safety assurance on the other hand. The introduction of this PhD-thesis starts with the position of omega-3 fatty acids in the human diet, their role in the human body, and the current recommendations for omega-3 fatty acids. Next, an introduction to the nutritional-toxicological conflict related to seafood is given, followed by a detailed description on how the evaluation of the intakes of nutrients and contaminants will be performed in this PhD-thesis. 15 Chapter I. General introduction 1. Omega-3 fatty acids and the human diet Scientific evidence exists that long chain (LC) omega-3 poly-unsaturated fatty acids (PUFAs) play an essential role in human health (Din et al, 2004; Kris-Etherton et al, 2002; Kris-Etherton et al, 2003; Ruxton, 2004; Ruxton et al, 2004; Ruxton et al, 2005; Sidhu, 2003; Simopoulos et al, 2000). To situate these omega-3 PUFAs in the overall group of fatty acids, the table below indicates the different types of fatty acids and gives some commonly occurring examples (Table I.1). Table I.1: The different types of fatty acids and some examples commonly occurring in food I. Saturated fatty acids II. Unsaturated fatty acids Butyric acid C4:0 II.a. Mono-unsaturated fatty acids Caproic acid C6:0 Oleic acid C18:1n-9 Lauric acid C12:0 II.b. Poly-unsaturated fatty acids Myristic acid C14:0 II.b.1. Omega-6 fatty acids Palmitic acid C16:0 Linoleic acid C18:2n-6 Stearic acid C18:0 γ-linolenic acid C18:3n-6 Arachidonic acid C20:4n-6 II.b.2. Omega-3 fatty acids α-linolenic acid C18:3n-3 Eicosapentaenoic acid C20:5n-3 Docosahexaenoic acid C22:6n-3 The group of PUFAs is divided into two groups: omega-3 (n-3) and omega-6 (n-6) PUFAs, differing in the position where the first double C-bound is located. Two PUFAs are called ‘essential fatty acids’ since they cannot be synthesized in the human body and are vital for physiological integrity. Therefore, they must be obtained from the diet. One is linoleic acid (LA, C18:2n-6) and belongs to the n-6 family. The other one is α-linolenic acid (LNA, C18:3n- 3) belonging to the n-3 family. These essential parent compounds can be converted in the human body to LC fatty acids, but humans can not interconvert n-3 and n-6 fatty acids (Ruxton et al, 2005). LA can be converted to arachidonic acid (AA, C20:4n-6) and further on to longer chain derivates, and LNA to eicosapentaenoic acid (EPA, C20:5n-3) in a first step and docosahexaenoic acid (C22:6n-3) in a next step. This conversion is summarized in Fig. I.1. 16 Chapter I. General introduction Fig. I.1 Desaturation and elongation of n-6 and n-3 fatty acids (based on Din et al (2004)) Different enzymatic steps are needed to fulfil these conversions which include desaturation and elongation. A crucial point is that the first enzymatic step in the desaturation of both LA and LNA involves the enzyme Δ6 desaturase. This results in a competition of both substrates for Δ6 desaturase. High intakes of LA have been suggested to decrease the desaturation of LNA to EPA and DHA and favour higher levels of AA. In developed countries dietary intakes of LA have increased over the last century from ~3% to 5-7% of total energy intake due largely to an increased consumption of LA-rich vegetable oils (Cunnane & Griffin, 2002; Liou et al, 2007; Ruxton et al, 2005).