Nutrition and Infectious Diseases: Shifting the Clinical Paradigm PDF
Preview Nutrition and Infectious Diseases: Shifting the Clinical Paradigm
Nutrition and Health Series Editors: Adrianne Bendich · Connie W. Bales Debbie L. Humphries Marilyn E. Scott Sten H. Vermund Editors Nutrition and Infectious Diseases Shifting the Clinical Paradigm Nutrition and Health Series Editors Adrianne Bendich Wellington, FL, USA Connie W. Bales Durham VA Medical Center Duke University School of Medicine Durham, NC, USA The Nutrition and Health series has an overriding mission in providing health professionals with texts that are considered essential since each is edited by the leading researchers in their respective fields. Each volume includes: 1) a synthesis of the state of the science, 2) timely, in-depth reviews, 3) extensive, up-to-date fully annotated reference lists, 4) a detailed index, 5) relevant tables and figures, 6) identification of paradigm shifts and consequences, 7) virtually no overlap of information between chapters, but targeted, inter- chapter referrals, 8) suggestions of areas for future research and 9) balanced, data driven answers to patient/health professionals questions which are based upon the totality of evidence rather than the findings of a single study. Nutrition and Health is a major resource of relevant, clinically based nutrition volumes for the professional that serve as a reliable source of data-driven reviews and practice guidelines. More information about this series at http://www.springer.com/series/7659 Debbie L. Humphries Marilyn E. Scott • Sten H. Vermund Editors Nutrition and Infectious Diseases Shifting the Clinical Paradigm Editors Debbie L. Humphries Marilyn E. Scott Yale School of Public Health Institute of Parasitology Yale University McGill University New Haven, CT Ste-Anne de Bellevue, QC USA Canada Sten H. Vermund Yale School of Public Health Yale University New Haven, CT USA Nutrition and Health ISBN 978-3-030-56912-9 ISBN 978-3-030-56913-6 (eBook) https://doi.org/10.1007/978-3-030-56913-6 © Springer Nature Switzerland AG 2021 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Humana imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Foreword The year 2019 marks the 50th anniversary of the World Health Organization monograph titled Interactions of Nutrition and Infection by the late Nevin Scrimshaw, Carl Taylor, and John Gordon. This groundbreaking work by three pioneers of public health was the first scientific compilation to describe the synergistic relationship between an individual’s nutritional state and risk of infectious diseases in the context of the high burden of under-five child mortality prevalent in those days. This relationship became widely known and described as the “vicious cycle of malnutrition and infection” that under- pinned the high mortality rates among children, especially in low-resource settings. These concepts and research done in this area are as salient today as they were 50 years ago; nearly half of all global child deaths attributed to infectious syndromes such as pneumonia and diarrhea have underlying undernutrition. Additionally, undernourished children also experience increased severity and frequency of infections and slow recovery, causing irrevocable long-term impact. At the Bill & Melinda Gates Foundation, dedi- cated to the maxim that all individuals have an equal opportunity to lead a healthy and productive life, our mission and work in maternal, newborn, and child health (MNCH) embodies understanding and addressing the close syn- ergistic link between undernutrition and infection. Our approach is evidence- based in the recognition that the vulnerability that marks being undernourished and micronutrient deficient can exponentially increase the risk of death due to an infection in populations living in low-income settings. For example, data from a study we supported found undernutrition to be one of the most power- ful risk factors, increasing the risk of pneumonia mortality by more than fivefold. Improvements in maternal, newborn, and child survival are among the most significant achievements in global health during the twenty-first cen- tury. Under-five child deaths have declined from 12.5 million in 1990 to 5.4 million per year in 2017. Yet, 149 million children under 5 are estimated to be stunted, 58 million experience wasting annually, 20.5 million are born low- birth weight, and 240 million women of reproductive age are undernourished (low BMI). Additionally, micronutrient deficiencies are common and multi- ple ones coexist in over a billion if not up to 2 billion people. Understanding the epidemiologic, biologic, molecular, and cellular mechanisms by which undernutrition can exacerbate both the occurrence of and survival from infec- tious disease is key, as is the role of infectious morbidity in preventing opti- mal growth and development. v vi Foreword As public health researchers who hail from two high-disease burden coun- tries in South Asia, having spent years studying and clinically observing undernutrition and infection coexist to exacerbate risk of mortality, we are excited that these conditions are again being comprehensively reviewed. Over the past few decades, numerous advances have been made in our under- standing of the field of nutrition and infection, spanning from unravelling the important linkages between infections and specific micronutrients to recog- nizing the emerging role of inflammation in linear growth failure (pre- and postnatal) and poor neurodevelopment. This book covers a vast array of top- ics with deep expositions into links between nutrition and a range of bacte- rial, viral, protozoan, and helminth infections and their health implications. Also, appropriately, it addresses these issues taking into account the current context of a world experiencing a nutrition and demographic transition lead- ing to more noncommunicable diseases and obesity, even while climate change challenges our global food systems and causes an emergence or resur- gence of infectious diseases and epidemics. Undernutrition and infectious diseases disproportionately impact the under-resourced populations of the world, and the imperative for accelerated progress toward achieving the sustainable development goals will only be fulfilled with a combined focus on the areas of health and nutrition. This well- written book and its state-of-the art compilation of a breadth of topics con- tributed by global experts provides its readership a closer and deeper understanding of the connection between nutrition and infectious diseases and the significant implications of that connection for addressing important challenges facing clinical and public health practice in the twenty-first century. Parul Christian Department of International Health, Program in Human Nutrition The Johns Hopkins Bloomberg School of Public Health Baltimore, MD, USA Anita Zaidi Department of Global Health Bill and Melinda Gates Foundation, Seattle, WA, USA Preface Undernutrition is estimated to affect over 800 million individuals, or more than one in ten persons on Earth [1]. This number includes those who are undernourished based on anthropometric measurements and those for whom at least one nutrient deficiency has been diagnosed. Though less well docu- mented, many of these individuals likely have been diagnosed with multiple macronutrient and/or micronutrient deficiencies, and many others may have suboptimal health attributable to nutritional deficiencies that have not been diagnosed. The combined prevalence of overweight and obesity, currently estimated to affect over half of adults worldwide [2], was recognized as a global crisis in 2000 with the publication of the World Health Organization (WHO) Technical Report on preventing and managing obesity [3]. Key to the recognition of the crisis was a growing awareness of the contribution of obe- sity and overweight to a variety of noninfectious diseases including heart disease and type-2 diabetes [4, 5]. While estimates of excess nutrition are most commonly based on overweight and obesity, the importance of consid- ering micronutrient status as a U-shaped curve, with negative health impacts at both low and high levels of intake, is increasingly recognized [6, 7]. The magnitude of both undernutrition and overnutrition is emphasized by data indicating that, among 5–19-year-old children and adolescents in 2016, 192 million (range 114–295) were moderately or severely underweight while 124 million (range 53–214) were obese [8]. Yet nutrition is often neglected within medical schools and clinics as a critical variable influencing human health [9–11] including outcomes of infectious diseases. Statistics for infectious diseases are even more dramatic than those for malnutrition. For example, it is estimated that, in 2016, diarrhea was the eighth leading cause of death overall, and the fifth leading cause of death in children under five [12], that 3–5 million are infected with influenza annually, that there were 219 million cases of malaria and 435,000 deaths in 2017 [13], and that 1.5–2 billion people are infected with helminth parasites [14]. Despite high rates of infectious diseases, such infections are often overlooked as contributors to, or consequences of, malnutrition. This is most recently and dramatically evident in the vast impacts of the COVID-19 pandemic on food production, distribution, and affordability [15–22]. A 1968 World Health Organization (WHO) monograph by Scrimshaw, Gordon and Taylor highlighted the intersections between nutrition and infec- tious disease [23]. Built on a much shorter review published 9 years earlier [24], the 1968 monograph described the conceptual pathways of influence between nutrition and infectious disease and provided an in-depth analysis of vii viii Preface associations between diarrhea and nutrition in India and Guatemala [23]. Through this monograph, Scrimshaw and colleagues were among the first to comprehensively describe both synergistic and antagonistic relationships between malnutrition and infection, noting that malnutrition was sometimes associated with increased infection severity and other times with decreased severity of infection [23]. Their monograph represented a critical synthesis the state of knowledge at that time derived from some 900+ references. This key conceptual document addressed interactions between nutrition and infec- tion, highlighted the impacts of malnutrition on immune responses to patho- gens, emphasized the reliance of pathogens on the host for their nutrients, and cited the energetic costs imposed on the host by infections. Now, over 50 years later, our knowledge base has expanded dramatically. Many concepts described by Scrimshaw and colleagues have been further substantiated, underlying mechanisms have been clarified, breadth of exam- ples have expanded, and range of possible points of interface between nutri- tion and infection have emerged. Our book thus provides a follow-up to the 1968 WHO monograph [23] by exploring what is currently known, and not known, about how malnutrition influences infectious diseases. To this end, we have brought together a diverse group of specialists who are intrigued by broader concepts. We have challenged authors to think “outside the box,” to consider questions that may not have previously occurred to them, and to dig into the literature to see what insights might exist. We have also asked authors to frame their remarks in a way that can be understood by nonspecialists. In this way, we hope that the chapters will be accessible to the nonexpert and provocative for the specialist. The book is structured into four parts. Part I lays out a conceptual frame- work for the book and introduces nonspecialists to key concepts in nutrition and immunology. Part II provides primers on the four traditional types of pathogens, viruses, bacteria, protozoans, and helminths. Part III addresses nutrition issues in several major diseases and conditions. Part IV addresses cross-cutting topics. Part I: The Foundations of the Nutrition-Infection Nexus This section begins with a conceptual model linking nutritional status and infectious diseases, followed by primers on nutrition and immune function that can serve as resources for students, researchers, and practitioners. Chapter 1 presents the linkage framework for nutritional status and infec- tious disease and explores the theory of causation in the context of nutrition- infection interactions [25]. Authors Humphries, Scott, and Vermund highlight the biological, physiological, and social determinants of both malnutrition and infection such that they represent a clinical and public health syndemic. More vulnerable populations (age, sex, immunosuppression, food insecure, unhygienic environment) are both more likely to have compromised nutri- tional status and increased exposure to infectious agents. The conceptual framework considers the effect of host nutrition on pathogen exposure, on the pathogen’s ability to break through natural host barriers and reach its target tissues, and on its ability to replicate and be transmitted to others. Whether Preface ix infection can be self-cured via immune responses will depend upon how severe and immunogenic the infection is and whether the immune response is effective in limiting the infection or leads to immunopathology. When treated with antibiotics, antivirals, antifungals, or anthelmintics, the effectiveness of drug interventions can be altered by intake of specific foods and/or underly- ing nutritional status (Chap. 1) [25]. Authors of all subsequent chapters were encouraged to allow this conceptual framework to shape how they approached their individual chapters. In Chap. 2, Barffour and Humphries examine human nutritional needs in the context of metabolism and physiology, as well as their influences on infections [26]. The chapter highlights evidence that immune responses rele- vant to infectious disease outcomes are altered by macro- and micronutrient deficiencies and supplementation, while noting the gaps in our current grasp of the origin and underpinning of these interactions. As a background to clini- cal needs and complexities, the authors review the specific macronutrients (carbohydrates, proteins, fats) and micronutrients (vitamins and minerals) that have metabolic relevance to infection-mediated disease states and atten- dant immune responses. The chapter serves as a pithy nutritional primer to give context to the rest of the book. Chapter 3 provides an invaluable “short course” on how the immune response to infection combines with various states of malnutrition to alter clinical outcomes [27]. Stephensen highlights how mammalian immune sys- tems have evolved to respond to specific infectious challenges with innate effector mechanisms that can clear such infections without harming those microbes in the oral and digestive tract microbiome that are essential for health. When innate responses do not clear infections, the adaptive immune system generates pathogen-specific immunity to clear the initial infection and prevent further infections. A vigorous immune system depends on energy supplied by diet, thus the immune response of nutritionally marginal persons may not be optimum. With severe, chronic, or repeated infections, the nutri- tional status of even a previously normal host can be compromised through damage of host tissues, suboptimal food intake or tolerance, malabsorption and nutrient loss, higher metabolic demands for nutrients, and perturbed nutrient transport or storage. That malnutrition compromises host immune defenses is a fundamental underpinning of risk of increased virulence of organisms and pathogenicity of infections [28]. Part II: Types of Infectious Diseases and Influences of Nutrition This section provides accessible overviews of major categories of pathogens and is intended to be used as antecedents of pathogen-focused subsequent chapters, as well as to serve as discrete educational resources for students, researchers, and practitioners. In Chap. 4, Berkley examines the specific elements of bacterial infections vis-à-vis nutritional status [29]. The human microbiome is dominated by bac- teria that can be beneficial or neutral or harmful, depending upon the mutual
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