Building bridges for better nutrition. Sight and Life We care about the world’s most vulnerable populations and exist to help improve their nutritional status. Acting as their advocates, we guide original nutrition research, disseminate its ndings and facilitate dialog to bring about positive change. For more information please visit www.sightandlife.org Donald S. McLaren, Klaus Kraemer Sight and Life Press, Third Edition 2012 Manual on Vitamin A De ciency Disorders ( VADD) ( Disorders ciency De A Vitamin on Manual Manual on Vitamin A De ciency Disorders (VADD) Donald S. McLaren ISBN 978-3-906412-58-0 Sight and Life | P.O. Box 2116 | 4002 Basel | Switzerland Klaus Kraemer Manual on Vitamin A Deficiency Disorders (VADD) Copyright © Sight and Life 2012 Sight and Life is a not-for-profit All rights reserved. nutrition think tank of DSM. Sight and Life Press We care about the world’s most vulnerable pop- c/o Sight and Life ulations, and exist to help improve their nutri- DSM Nutritional Products Ltd tional status. Acting as their advocates, we PO Box 2116 guide original nutrition research, disseminate 4002 Basel its findings and facilitate dialog to bring about Switzerland positive change. We believe that the right mix of Phone +41 (0) 61 815 88 23 funding, knowledge, technology and policy will Fax +41 (0) 61 815 81 90 lead to better health. We work through advo- Email [email protected] cacy and leadership to address societal chang- Web www.sightandlife.org es affecting dietary quality. We act responsibly to disseminate information that reflects current Publications fromSight and Life can be obtained knowledge and evolving scientific evidence. We from the above address. 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McLaren, Klaus Kraemer Sight and Life Press, Third Edition 2012 Manual on Vitamin A Deficiency Disorders (VADD) II Acknowledgements The Sight and Life Manual on Vitamin A We would like to take this opportunity to Deficiency Disorders (VADD) is now appearing acknowledge the support we have experienced in its 3rd edition. Although our scope has broad- during the last couple of years in preparing the ened from “sight”, a single focus on vitamin A, to 3rd edition of this book. There are many people “life”, a multiple micronutrient focus, we believe to acknowledge who have been associated with that vitamin A remains sufficiently important and this project. We would therefore like to start with interesting for us to dedicate a whole book to this apologies to those who we may have omitted nutrient. to mention. Extraordinary thanks go to Svenia Sayer-Ruehmann and Anne-Catherine Frey from This book not only draws on the latest scient- the Sight and Life team for their skilful tech- ific research and expert insights, but also benefits nical support, without which this publication greatly from the work of previous generations would have never been completed. Further, our of scientists and policy-makers. As a result, it is Sight and Life interns Laurence Curty and Sarah almost impossible to acknowledge all those who Diouf both merit special mention. We continue have contributed their expertise. Key sources in- to appreciate Yvonne Bearne for her proofread- clude, among others, journal articles, policy state- ing, and the Burger Druck team for laying out the ments, reports, fact sheets, guidelines, reference book. We also wish to thank the World Health books, websites and – of course – the data and Organization for its kind permission to reprint the research to be found in Sight and Life Magazine vitamin A deficiency world maps. Last but not itself. least, Royal DSM deserves our special apprecia- tion for its continuous support of Sight and Life; in particular, we would also like to thank Stephan Tanda, Chairman of the Sight and Life Steering Committee, for writing his encouraging foreword to this volume. III3 PrefAce This Third Edition of the Sight and Life demands of the time do not seem to permit the Manual on Vitamin A Deficiency Disorders luxury of extreme specialization. Henceforth (VADD) is likely to be the last. This is not be- source materials like this manual will also need cause there is nothing more to learn about the sub- to focus more on VMD in general. Sight and ject. It is because in recent years there has been Life sees this as a key role for itself in the future a major shift in the approach to the control of as we continue to evolve to ensure that we make a vitamin and mineral deficiencies (VMD) or multi- valuable contribution. micronutrient deficiencies (MMD) – including VADD. This is largely due to the fact that it is now The Third Edition has not surprisingly in- well recognized that VMD tend to occur together creased considerably in size and includes three rather than on their own – a tendency that is most new chapters. The first of these is specifically likely explained by the fact that most micronutri- titled ‘Foreground’ (as opposed to Background), ents are found in the same classes of foodstuffs, in order to emphasize, from the start, that the especially fruit, vegetables, fish and meat. Until focus of the Manual is on the control of VADD recently, it was general practice to identify and and that this objective should be kept in mind combat the most serious forms of deficiency, usu- throughout the book. Chapter 2 illustrates how ally of a single micronutrient. Prominent among essential and versatile the vitamin A molecules these have been vitamin A, iron, iodine, zinc and are – together with their close relatives found folate. Today, although there remains a great deal in nature, the carotenoids. Without them human to be learned about the individual roles and func- life, vision, growth and development would not tions of most micronutrients in human nutrition, be possible. The bioavailability of carotenoids interest is increasingly focused on their interrela- has become so important that it now requires its tionship, especially as micronutrient intervention own chapter (Chapter 5). In addition, the effect programs are on the increase and many are in the that the acute phase response (APR) has on serum process of being scaled-up. retinol levels is of such significance that, after an introduction to the issue in Chapter 7, it remains a The recognition of the interconnected relation- prominent feature in several subsequent chapters. ship of the micronutrients is further highlighted As so often in the field of VMD, the work on APR by the disbanding of the International Vitamin A has been pioneered in relation to VADD, but its Consultative Group (IVACG) and International effect in relation to other micronutrient deficien- Nutritional Anemia Consultative Group (INACG), cies has received little attention and much more which were set up more than thirty years ago to research is necessary. assist in the control of specific nutritional defi- ciencies. They have been replaced by the all en- This edition also includes in Chapter 12 the compassing Micronutrient Forum (MF), which latest available data on the global occurrence held its first scientific meeting in April 2007. It is of VAD from the World Health Organization no exaggeration to say that hundreds of nutrition- (WHO). Attention is drawn to the inability, over related scientists, whose knowledge and research the past several years, to determine accurate prev- efforts were virtually confined to a single micro- alence figures for the number of blind persons liv- nutrient, will now have to broaden their area of ing in any given country or region of the world or expertise and research. Rightly or wrongly, the within any vulnerable group etc., due to the deci- IV Preface sion to no longer report non-blinding xerophthal- rophthalmia) had been brought under control to a mia and blinding xerophthalmia separately. As a large extent. However, at around the same time it consequence, while data on other causes of blind- was recognized that the problem had several other ness are becoming increasingly precise, vitamin A concerning elements: deficiency blindness is included under the heading of ‘other causes of childhood blindness’