- Email: [email protected]
What is clinical nutrition? Understanding the epistemological foundations of a new discipline
Clinical Nutrition ESPEN 11 (2016) e63ee66
Contents lists available at ScienceDirect
Clinical Nutrition ESPEN journal homepage: http://www.clinicalnutritionespen.com
Opinion paper
What is clinical nutrition? Understanding the epistemological foundations of a new discipline Diana Cardenas a, b, * a b
Laboratoire Logiques de l'Agir, Philosophy Department, University of Franche Comt e, Besançon, France , Colombia Research Institute on Nutrition, Genetics and Metabolism, University El Bosque, Bogota
a r t i c l e i n f o
s u m m a r y
Article history: Received 29 May 2015 Accepted 1 October 2015
Background: Although the therapeutic and economic efficacy of nutrition has been proven, optimal nutritional care is still scarce among hospital and ambulatory patients. Thus malnutrition is still highly prevalent. We identify as an underlying cause the absence of a common understanding of clinical nutrition as a discipline. The aim of this paper is to establish the epistemological foundations of clinical nutrition and to characterize it as a science. Methods and results: From the standpoint of historical epistemology, we examine the historical conditions that determine i) the main object of knowledge, ii) the nature and iii) domain of this science. Our hypothesis is that clinical nutrition as a science was formed in the second half of the twentieth century as an outcome of the integration of medicine and nutrition and underpinned by a primary transformation of the “nutrient” concept. We identify malnutrition as the primary practical and research domain of knowledge. Conclusion: Clinical nutrition is an autonomous empirical science that can be characterized as a basic and applied science. Its wide multi-disciplinarity guarantees its future. © 2015 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.
Keywords: Epistemology History of medicine Nutritional sciences Diseases-related malnutrition Nutritional support
1. Introduction The link between humans and food has been studied since Antiquity. In fact, human beings have learnt that their environment, especially food, can interfere with their health. Nutrition is now recognized as a determinant in chronic and acute diseases. The efficacy of nutritional care has been extensively documented, and has enabled improvement in nutritional and biochemical markers, quality of life and reduction in mortality, morbidity, as well as in the length of hospitalization and rehospitalizations. Moreover, there is growing evidence that nutrition may contribute to the costeffectiveness and financial sustainability of health care systems [1]. Nevertheless, malnutrition is still highly prevalent in hospitals but also in ambulatory care clinics, among children, adults, and geriatric patients [2]. Researchers have proposed reasons to account for the persistence of inadequate nutritional care and the prevalence of high
* Laboratoire Logiques de l'Agir, Philosophy Department, University of Franche , 1 rue Goudimel, 25030 Besançon Cedex, France. Comte E-mail address: [email protected].
malnutrition. Academic arguments range from of the absence of full recognition of clinical nutrition specialists, difficulties in implementing national educational programs in medical and other health care professionals, to lack of faculty expertise in nutrition in medical schools and training. Other practical factors include the lack of consistent criteria for diagnosing malnutrition, a lack of confidence when addressing nutrition issues as well as inadequate attention to the nutrition support of hospitalized patients [3]. Economic factors have also been reported, such as the heterogeneous nature of coverage or reimbursement of nutritional care products and services across countries [1]. Given that the impact of malnutrition is well-known and that the efficacy of nutritional care has been proven, one may wonder why it is still so difficult to overcome those difficulties. Our hypothesis is that there is a widespread and deeply rooted problem: the lack of a common understanding of clinical nutrition as a science. In fact, “clinical nutrition” is not a new phrase: it has been used in scientific research publications for the last 60 years at least. The phrase was first used to refer to the application of nutrition principles to the specific field of “clinics” [4]. The concept of “clinic” (klinein, lying down) is originally related to the physician's practice at the patient's bedside (i.e. all medical activities in connection with
http://dx.doi.org/10.1016/j.clnesp.2015.10.001 2405-4577/© 2015 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.
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D. Cardenas / Clinical Nutrition ESPEN 11 (2016) e63ee66
patients). Thus we may raise the following question: is clinical nutrition to be considered only as the application of the science of nutrition to “clinics”? If so, this implies that we consider clinical nutrition to be a sub-discipline of nutrition. On the contrary, we think that clinical nutrition is an autonomous discipline: an outcome of the integration of medicine and nutrition, underpinned by a primary transformation of the “nutrient” concept. In this paper, we will therefore attempt to characterize clinical nutrition as a science and to define its epistemological foundations. 2. Method Epistemology is the area of philosophy that investigates the foundations and the limits of human knowledge. It aims to characterize existing sciences in order to assess their value e in particular to decide whether they are entitled to approach the ideal of a ascertainable and genuinely justified knowledge [5]. To achieve this objective, epistemology describes how a given scientific discipline provides and develops its theories and gauges the logic and cognitive value of such theories. In our study, we draw on the French approach, especially the methodology of “historical epistemology”, with a view to answering three fundamental questions: i) How was clinical nutrition established ii) What are the object and the domain of this science? iii) What is clinical nutrition? 3. The origins of clinical nutrition In order to understand what we consider as clinical nutrition today it is necessary to look for its epistemological foundations. For this purpose, we have searched the history of sciences for the events that favoured the emergence of this discipline. We identified as the main key fact the primary transformation of the “nutrient” concept achieved as the result of the progress and expansion of medical and human nutrition knowledge. In fact, the concept of the nutrient evolved in the second half of the 20th century to the point of being understood as a medical or artificial nutrient capable of feeding the sick patient while facing new challenges and adapting to evolving medical practices (i.e., new medicines, surgical techniques, technology and facilities). Hence, the clue to understanding the origins of clinical nutrition is to examine the causes of its transformation in the last decades of the 20th century. 3.1. The nutrient from pre-scientific to scientific era The first conceptual idea of the word “nutrient” can be found in Aristotle's biology [6]. Indeed, for Aristotle there was a substance extracted from food that after becoming blood could turn into any part of the body. This notion evolved in the XVIII century after the chemical revolution brought about by the works of AntoineLaurent Lavoisier, Joseph Priestley and Carl Scheale, which demonstrated the true nature of oxygen and the process of oxidation [7]. However, throughout the 18th century as in Ancient times, food was seen as being constituted of a single universal substance called the “nutrient”. Indeed, the word nutrient, from the Latin nutrimentum (any food substance which serves as nutrition), was defined in 1854 by the doctor Lucien Corvisart as a “food substance that can be assimilated directly.” [8] The role of a nutrient was then to be assimilated. This transformation, which involved biochemical pathways, allowed the nutrient to maintain its nutritional status, and therefore to contribute to health. The work of the English chemist William Prout in the 1830s brought about the notion that there was not just a single nutrient but a variety of nutrients (fat, carbohydrates and proteins) in food. For the next hundred years, the history of the science of nutrition was then marked by the discovery of most of the nutrients and their specific physiological
functions. As a consequence in the first decade of the 20th century, “dietetics” was established as a separated paramedical profession in America, to help the government make optimal use of Armerica's food resources in wartime. In Europe, dietetics was later developed also as an instrument of state policies. Thus, nutrition became a political concern rather than a scientific priority [9]. This is illustrated by the lag in the progress of nutrition in the clinical setting. The way of feeding the sick changed with the emergence of modern hospitals in Europe [10]. The new design of the hospitals, introduced by the political and social changes that occurred after the French Revolution in the nineteenth century, went beyond the notion of a hospice for the poor. The architecture of the hospital was now based on therapeutic and hygienic principles. Hospitals became a privileged spaces for medical education. In fact, the hospital setting favoured the advances of clinical sciences because a significant number of patients could be observed, studied (and compared), and because the hospital made it possible to conduct autopsies and thus develop anatomopathology. In that context, the religious meaning of feeding (as an act of charity) that had prevailed until then was replaced by medical feeding based on Hippocratic dietetic principles. However, doctors rapidly lost interest in diet and abandoned the feeding care and research on nutrition, leaving it in the hands of hospital administrators. And indeed, administrators in the nineteenth century did recognize nutrition in the clinical setting to be important: nutrition could reduce the length of patients' stay at the hospital, speed up convalescence, prevent rehospitalisation and diminish the cost of care [11]. 3.2. The nutrient from the 20th century In the first half of the 20th century, nutrition was defined as “the science of food (and the ingredients of food known as nutrients), and its relation to health” [12]. The aim of this science was to contribute to the well-being and public health conditions. Nutritional care in the hospital and other medical settings was scarce. For decades, dietary practices in clinical settings relied on outdated principles. For example, while human nutrition science had already determined the principal nutrients and the notion of daily ratio and calorie needs, patients were still being fed according the ancient principles of an “absolute diet”, ignoring all notions of quantity and quality. Thus, there was a gap in the advancement of knowledge between public health research and the clinical field. In the post-war decades, doctors slowly developed a new interest in and expressed concerns about the feeding of hospitalized patients. Feeding patients in various situations while coping with the progress of surgical techniques and other medical interventions became a real challenge. In fact, such situations, leading to undernutrition, had an impact on morbidity and mortality. In 1932, Cuthbertson had described in detail the metabolic responses of four patients with lower limb injuries [13]. In 1936, the surgeon HO Studley had published a statistical analysis that quantified the relationship between weight loss and mortality. He demonstrated that a reduction of more than 20% of body weight resulted in a postoperative mortality rate of 33%, while a group of patients with a weight loss of less than 20% had a postoperative mortality rate within 3% [14]. In 1947, it was recognized that the quantity and quality of food could distinctly influence the outcome of infectious diseases, surgical or traumatically wounds, burns and blood loss [15]. Thus, the challenge was to feed the patients by any possible route (i.e., oral, enteral or parenteral) to prevent malnutrition and modulate the metabolic response to injury. However, technically the parenteral route was impossible to perform, which triggered extensive research on the subject. In the 1960s, the prevailing dogma was still that ‘‘feeding entirely by vein is impossible; even if
D. Cardenas / Clinical Nutrition ESPEN 11 (2016) e63ee66
it were possible, it would be impractical; and even if it were practical, it would be unaffordable.’’ [16] Such a difficulty was not new: since the description of circulation by William Harvey in the seventeenth century, veins had been imagined as a route of administration for nutrients. Thanks to some significant technical progress, in 1966, Beagle puppies, could be totally fed by the parenteral route for the first time, ensuring the sole nutritional support for growth, development and metabolic support. Two years after that experiment, it became possible for human beings to be fed in the same way. Furthermore, enteral nutrition was developed simultaneously, as risks of hyper-nutrition by the parenteral route and the role of the intestine were being acknowledged (For a complete history of parenteral nutrition see Ref. [16]). Thus, during the 1970s nutrients were no longer only associated with an oral diet, but with artificial means. First, this means that an invasive procedure, either the placement of a catheter for parenteral administration or a tube for enteral nutrition. These techniques are known today as “parenteral/enteral artificial nutrition” and their application as “nutritional support”. Thus, the word “artificial” no longer refers to some food property (the result of a culinary preparation, for instance) as in Hippocratic medicine, but to the particular method of administration and production of nutrients. The second meaning of “artificial” is that nutrients are not the outcome of agronomical production and that their availability does not depend on agricultural policies: nutrients are now the outcome of pharmacological industrial productions. Thus, we may find a wide range of products for nutritional support (i.e., “food for medical purpose”, “nutrition supplement” or “medical foods”). As a result, in both Europe and the United States, products for nutrition support are required to have specific bill regulation with specific legislations and guidelines. Those products are meant for patients with special nutritional needs and health care professionals must deliver indications for nutritional support under medical prescription and supervision. This implies a major change in medical practice since the products of nutrition support are now comparable to the practice in pharmaceuticals [1]. Beside these two meanings, the new concept of the nutrient has undergone another essential transformation, as its function is to reach beyond its nutritional objective. So key nutrients called “immunonutrients” (i.e., glutamine, arginine, citrulline, omega-3) can modulate inflammatory response and help restore immunological and other biological functions. Consequently, nutrients are administered not only for feeding, but to improve host defences and outcomes [17]. The novelty is that we attribute a pharmacological-type action to nutrients, and that they are investigated as such [18]. This aims to guarantee security to the patient, as nutrients must now be assessed under adequate and wellcontrolled clinical investigations, as any new drugs require. 4. Defining clinical nutrition as a science Clinical nutrition can be defined as both an autonomous empirical science and as an art. As an empirical science (i.e. knowledge derived from or guided by experiment), it interacts with other biological science like biochemistry, pharmacology and physiology. Autonomy (i.e. process of a science differentiating itself from other disciplines) can be defined as “a relative independence from other related disciplines, including both ‘sociological’ characteristics, such as the existence of research groups and associations, and ‘epistemological’ characteristics, such as separate methods and theory development” [19]. Table 1 summarizes the epistemological and sociological criteria of clinical nutrition. As an art (i.e. techne, practice), the scientific principles and theories of clinical nutrition are applied through the practice of nutritional care. Nutritional care is a global process that includes
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Table 1 Criteria for disciplinary autonomy of clinical nutrition. Epistemological characteristics A separable research object: The artificial nutrient Separate methods for empirical investigations: pharmaconutrient approach; tracer methodology, etc. An independent theory development or invention of a new theory: Artificial nutrient concept, parenteral and enteral nutrition principles, etc. A common conceptual apparatus: Malnutrition, disease-related malnutrition, immunonutrients, etc. Sociological features A core group of researchers: ESPEN Special interest groups, etc. Common communication channels: Clinical Nutrition Journal, American Journal of Clinical Nutrition, etc. Separate conferences, meetings, etc: ESPEN congress, ASPEN congress, etc. Associations or institutions at a national and/or international level: SFNEP France, SBNC Belgium, DGEM Germany etc. The existence of teaching and training curricula, in addition to courses which are provided at universities or colleges, or offered as commercial courses to trade and industry: LLL ESPEN course, Adriatic Club of Clinical Nutrition (ACCN), etc.
screening, diagnostics, treatments, monitoring and audit in all types of care facilities (hospital, nursing homes and community) [2]. This leads to considering clinical nutrition in the scope of the patient-health care provider interaction in opposite to the organismeenvironment interaction characteristic of human nutritional science (Fig. 1). This has biological, sociological and ethical implications. 5. The domain of clinical nutrition: malnutrition In this context, the domain (a field or scope of knowledge and activity in science) of clinical nutrition can be defined by a series of areas: malnutrition, feeding, metabolism, health and disease. Indeed, clinical nutrition is concerned with all these aspects but there is one that defines it precisely. The main problem addressed by clinical nutrition is malnutrition [20]. This means that clinical nutrition e basic knowledge and practice through nutritional care e is supposed to help fight against malnutrition. Thus, malnutrition is what best defines the domain of knowledge and practice of clinical nutrition. Even if there is some general agreement about the need to fight malnutrition, this concept raises semantic, epistemological and biological controversies. Are malnutrition and undernutrition synonymous? Are malnutrition/undernutrition/obesity to be understood as risk factors or as diseases? How can they be defined biologically, what criteria can be used? There is no consensus. We consider that the term “malnutrition” must not be considered as synonymous with “undernutrition” but as a general term encompassing a wide variety of nutritional statuses: pure starvation, disease-related malnutrition (cachexia), sarcopenia and frailty, as well as overweight, obesity and micronutrient abnormalities. In
Fig. 1. The interdisciplinarity of clinical nutrition.
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D. Cardenas / Clinical Nutrition ESPEN 11 (2016) e63ee66
that sense, the scope of clinical nutrition must include obesityrelated nutritional and metabolic challenges [21]. The consensus criteria to unify the international terminology published recently by Cederholm T et al. proposes the term “nutritional disorders” as a general term encompassing malnutrition, overnutrition and micronutrient abnormalities and introduce a hierarchical arrangement of the conditions [22]. In our opinion, based on the complexity of those nutritional syndromes, there is no place for this kind of organization. Moreover, “nutritional disorder” (i.e. the absence of order or the state of not being arranged in an orderly manner) and “malnutrition” (i.e. malus bad, badly) can be synonymous in the clinical field, both giving an axiological meaning to the term. Thus there is no place for introducing an extra term that doesn't clarify the nosology of malnutrition. The semantic ambiguities, and the normative and axiological status of concept of malnutrition must be further studied. Efforts should be made to modify the International Classification of Diseases (ICD) coding and the recognition of diverse malnutrition conditions.
malnutrition and disease and relying on a new concept of nutrient. It cannot be subsumed under nutritional science, as it is not to be considered as an organismeenvironment interaction but as an autonomous science, with a proper core of knowledge, domain, and mode of intervention, under the patientehealth care provider interaction. Determining the epistemological status of clinical nutrition may help to consolidate the discipline, face and integrate the ongoing production of knowledge and address the accelerating social, technological, environmental and ethical challenges raised by this science. Statement of authorship Diana Cardenas carried out the study and the whole writing of the manuscript. Conflict of interest There is no conflict of interest to declare.
6. Perspectives for clinical nutrition Statement and funding sources Understanding the epistemological foundation of clinical nutrition may lead to ethical, and academic challenges. First, performing and organizing clinical nutritional care may lead to ethical issues that should be taken into account. This particularly concerns the rationalization and standardization of nutritional care that may question justice and equality in health care. Second, nutritional support involves a multidisciplinary team in care implying the provision of food and drink by mouth econsidered as basic care e but also artificial nutrition legally considered as a treatment. This puts in a constant tension the ethics of care and cure. In that sense, the four ethical elements of care, attentiveness, responsibility, competence and responsiveness, must be placed at the heart of the matter. The bioethical principles of respect of autonomy, non-maleficence, beneficence and justice can be questioned in the practise of nutritional support [23]. The ethics of clinical nutrition must be studied in depth. The recognition of clinical nutrition as an autonomous discipline is a new phenomenon and will inevitably lead to some readjustment of existing professional boundaries. Clinical nutrition is usually subsumed under medical or nutritional-dietetic sciences. Medical students need to attend more courses and training on clinical nutrition, particularly courses on the basics of nutrition, and dieticians need to have more courses and training on clinical nutrition, particularly courses on the basics of medicine. An interdisciplinary speciality must be recognized. This must be a veritable speciality not a subspeciality of gastroenterology or surgery, endocrinology. More research and efforts must be combined to determine consensual core competencies and contents for clinical nutrition. We have proposed a definition of clinical nutrition based on its epistemological status, object and specific domain of knowledge. Clinical nutrition is a basic interdisciplinary and applied science, concerned with malnutrition (under/overnutrition/micronutrient abnormalities). Its aim is to apply the principles of nutritional support (i.e. artificial nutrients) within the framework of nutritional care in order to ensure the nutritional status and modulate other biological functions to positively influence patient treatment and outcome. 7. Conclusion Clinical nutrition is the outcome of a new vision, typical of the twentieth century school of thought: a vision defining the way the patient must be fed, establishing a close relationship between
No funding sources. Acknowledgements The author wishes to thank Dr Carole Birkan-Berz of the Uni Paris 3 e Sorbonne Nouvelle who assisted in the editing of versite the manuscript. References verac H. Health economics ev[1] Walzer S, Droeschel D, Nuijten M, Chevrou-Se idence for medical nutrition: are these interventions value for money in integrated care? Clin Econ Outcomes Res 2014;6:241e52. [2] Ljungqvist O, van Gossum A, Sanz ML, de Man F. The European fight against malnutrition. Clin Nutr 2010;29:149e50. [3] Kris-Etherton PM, Pratt Ch A, Saltzman E, Van Horn L. Introduction to nutrition education in training medical and other health care professionals. Am J Clin Nutr 2014;99(Suppl.):1151Se2S. [4] Clinical nutrition briefs. Nutr Rev 1954;12(4):1. l'epsitemologie. Paris: Ellipses; 2000. [5] Soler L. Introduction a [6] Aristote. Les parties des Animaux, traduction by Pellegrin P. Paris: Flammarion; 2011. e le mentaire de Chimie, Œuvres I. Paris: Imprimerie [7] Lavoisier AL. Traite riale; 1864. Impe ; 1854. [8] Corvisart L. Etudes sur les Aliments et les nutriments. Paris: Labe [9] Cannon G. The rise and fall of dietetics and of nutrition science 4000 BCEe2000 CE Public Health Nutr;8(6A):701e5. tit vient en mangeant!. In: Histoire de l'alimentation a [10] Nardin A. L'appe ^pital XV-XX sie cles. Paris: Edoin-Muse e de l'Assistance Publique; 1998. l'ho gime alimentaire dans les ho ^pitaux. Substances alimentaires et [11] Payen A. Re liorer, de les conserver et d'en reconnaître les alte rades moyens de les ame tions. Paris: Hachette; 1865. p. 513. [12] Stare FJ. Why the nutrition science? Nutr Rev 1950;8(1):1e5. [13] Cuthbertson DP. Observations on the disturbance of metabolism produced by injury to the limbs. Q J Med 1932;1:233e4. [14] Studley HO. Percentage weight loss, a basic indicator of surgical risk in patients with chronic peptic ulcer. JAMA 1936;106:458. [15] Stare FJ. Medical and public education in nutrition. Nutr Rev 1947;5(1):1e3. [16] Dudrick SJ. History of parenteral nutrition. J Am Coll Nutr 2009;28:243e51. [17] Mizcock BA. Immunonutrition and critical illness: an update. Nutrition 2010;26:701e7. [18] Jones NE, Heyland DK. Pharmaconutrition: a new emerging paradigm. Curr Opin Gastroenterol 2008;24:215e22. [19] Kristiansen M. Emerging disciplines in the behavioural sciences. Assessment of disciplinary autonomy by terminological conceptual analysis. Unesco Alsed-LSP 2000;23:1e19. [20] Pierre S. ESPEN 2011: the present and the future. Clin Nutr 2011;30:405e6. [21] Barazzoni R, Van Gossum A, Singer P. Should ESPEN engage in facing the obesity challenge? Clin Nutr 2015;34:169e70. [22] Cederholm T, Bosaeus I, Barazzoni R, Bauer J, Van Gossum A, Klek S, et al. Diagnostic criteria for malnutrition e an ESPEN Consensus Statement. Clin Nutr 2015;34:335e340. [23] Orrevall Y. Nutritional support at the end of life. Nutrition 2015;31:615e6.
Contents lists available at ScienceDirect
Clinical Nutrition ESPEN journal homepage: http://www.clinicalnutritionespen.com
Opinion paper
What is clinical nutrition? Understanding the epistemological foundations of a new discipline Diana Cardenas a, b, * a b
Laboratoire Logiques de l'Agir, Philosophy Department, University of Franche Comt e, Besançon, France , Colombia Research Institute on Nutrition, Genetics and Metabolism, University El Bosque, Bogota
a r t i c l e i n f o
s u m m a r y
Article history: Received 29 May 2015 Accepted 1 October 2015
Background: Although the therapeutic and economic efficacy of nutrition has been proven, optimal nutritional care is still scarce among hospital and ambulatory patients. Thus malnutrition is still highly prevalent. We identify as an underlying cause the absence of a common understanding of clinical nutrition as a discipline. The aim of this paper is to establish the epistemological foundations of clinical nutrition and to characterize it as a science. Methods and results: From the standpoint of historical epistemology, we examine the historical conditions that determine i) the main object of knowledge, ii) the nature and iii) domain of this science. Our hypothesis is that clinical nutrition as a science was formed in the second half of the twentieth century as an outcome of the integration of medicine and nutrition and underpinned by a primary transformation of the “nutrient” concept. We identify malnutrition as the primary practical and research domain of knowledge. Conclusion: Clinical nutrition is an autonomous empirical science that can be characterized as a basic and applied science. Its wide multi-disciplinarity guarantees its future. © 2015 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.
Keywords: Epistemology History of medicine Nutritional sciences Diseases-related malnutrition Nutritional support
1. Introduction The link between humans and food has been studied since Antiquity. In fact, human beings have learnt that their environment, especially food, can interfere with their health. Nutrition is now recognized as a determinant in chronic and acute diseases. The efficacy of nutritional care has been extensively documented, and has enabled improvement in nutritional and biochemical markers, quality of life and reduction in mortality, morbidity, as well as in the length of hospitalization and rehospitalizations. Moreover, there is growing evidence that nutrition may contribute to the costeffectiveness and financial sustainability of health care systems [1]. Nevertheless, malnutrition is still highly prevalent in hospitals but also in ambulatory care clinics, among children, adults, and geriatric patients [2]. Researchers have proposed reasons to account for the persistence of inadequate nutritional care and the prevalence of high
* Laboratoire Logiques de l'Agir, Philosophy Department, University of Franche , 1 rue Goudimel, 25030 Besançon Cedex, France. Comte E-mail address: [email protected].
malnutrition. Academic arguments range from of the absence of full recognition of clinical nutrition specialists, difficulties in implementing national educational programs in medical and other health care professionals, to lack of faculty expertise in nutrition in medical schools and training. Other practical factors include the lack of consistent criteria for diagnosing malnutrition, a lack of confidence when addressing nutrition issues as well as inadequate attention to the nutrition support of hospitalized patients [3]. Economic factors have also been reported, such as the heterogeneous nature of coverage or reimbursement of nutritional care products and services across countries [1]. Given that the impact of malnutrition is well-known and that the efficacy of nutritional care has been proven, one may wonder why it is still so difficult to overcome those difficulties. Our hypothesis is that there is a widespread and deeply rooted problem: the lack of a common understanding of clinical nutrition as a science. In fact, “clinical nutrition” is not a new phrase: it has been used in scientific research publications for the last 60 years at least. The phrase was first used to refer to the application of nutrition principles to the specific field of “clinics” [4]. The concept of “clinic” (klinein, lying down) is originally related to the physician's practice at the patient's bedside (i.e. all medical activities in connection with
http://dx.doi.org/10.1016/j.clnesp.2015.10.001 2405-4577/© 2015 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.
e64
D. Cardenas / Clinical Nutrition ESPEN 11 (2016) e63ee66
patients). Thus we may raise the following question: is clinical nutrition to be considered only as the application of the science of nutrition to “clinics”? If so, this implies that we consider clinical nutrition to be a sub-discipline of nutrition. On the contrary, we think that clinical nutrition is an autonomous discipline: an outcome of the integration of medicine and nutrition, underpinned by a primary transformation of the “nutrient” concept. In this paper, we will therefore attempt to characterize clinical nutrition as a science and to define its epistemological foundations. 2. Method Epistemology is the area of philosophy that investigates the foundations and the limits of human knowledge. It aims to characterize existing sciences in order to assess their value e in particular to decide whether they are entitled to approach the ideal of a ascertainable and genuinely justified knowledge [5]. To achieve this objective, epistemology describes how a given scientific discipline provides and develops its theories and gauges the logic and cognitive value of such theories. In our study, we draw on the French approach, especially the methodology of “historical epistemology”, with a view to answering three fundamental questions: i) How was clinical nutrition established ii) What are the object and the domain of this science? iii) What is clinical nutrition? 3. The origins of clinical nutrition In order to understand what we consider as clinical nutrition today it is necessary to look for its epistemological foundations. For this purpose, we have searched the history of sciences for the events that favoured the emergence of this discipline. We identified as the main key fact the primary transformation of the “nutrient” concept achieved as the result of the progress and expansion of medical and human nutrition knowledge. In fact, the concept of the nutrient evolved in the second half of the 20th century to the point of being understood as a medical or artificial nutrient capable of feeding the sick patient while facing new challenges and adapting to evolving medical practices (i.e., new medicines, surgical techniques, technology and facilities). Hence, the clue to understanding the origins of clinical nutrition is to examine the causes of its transformation in the last decades of the 20th century. 3.1. The nutrient from pre-scientific to scientific era The first conceptual idea of the word “nutrient” can be found in Aristotle's biology [6]. Indeed, for Aristotle there was a substance extracted from food that after becoming blood could turn into any part of the body. This notion evolved in the XVIII century after the chemical revolution brought about by the works of AntoineLaurent Lavoisier, Joseph Priestley and Carl Scheale, which demonstrated the true nature of oxygen and the process of oxidation [7]. However, throughout the 18th century as in Ancient times, food was seen as being constituted of a single universal substance called the “nutrient”. Indeed, the word nutrient, from the Latin nutrimentum (any food substance which serves as nutrition), was defined in 1854 by the doctor Lucien Corvisart as a “food substance that can be assimilated directly.” [8] The role of a nutrient was then to be assimilated. This transformation, which involved biochemical pathways, allowed the nutrient to maintain its nutritional status, and therefore to contribute to health. The work of the English chemist William Prout in the 1830s brought about the notion that there was not just a single nutrient but a variety of nutrients (fat, carbohydrates and proteins) in food. For the next hundred years, the history of the science of nutrition was then marked by the discovery of most of the nutrients and their specific physiological
functions. As a consequence in the first decade of the 20th century, “dietetics” was established as a separated paramedical profession in America, to help the government make optimal use of Armerica's food resources in wartime. In Europe, dietetics was later developed also as an instrument of state policies. Thus, nutrition became a political concern rather than a scientific priority [9]. This is illustrated by the lag in the progress of nutrition in the clinical setting. The way of feeding the sick changed with the emergence of modern hospitals in Europe [10]. The new design of the hospitals, introduced by the political and social changes that occurred after the French Revolution in the nineteenth century, went beyond the notion of a hospice for the poor. The architecture of the hospital was now based on therapeutic and hygienic principles. Hospitals became a privileged spaces for medical education. In fact, the hospital setting favoured the advances of clinical sciences because a significant number of patients could be observed, studied (and compared), and because the hospital made it possible to conduct autopsies and thus develop anatomopathology. In that context, the religious meaning of feeding (as an act of charity) that had prevailed until then was replaced by medical feeding based on Hippocratic dietetic principles. However, doctors rapidly lost interest in diet and abandoned the feeding care and research on nutrition, leaving it in the hands of hospital administrators. And indeed, administrators in the nineteenth century did recognize nutrition in the clinical setting to be important: nutrition could reduce the length of patients' stay at the hospital, speed up convalescence, prevent rehospitalisation and diminish the cost of care [11]. 3.2. The nutrient from the 20th century In the first half of the 20th century, nutrition was defined as “the science of food (and the ingredients of food known as nutrients), and its relation to health” [12]. The aim of this science was to contribute to the well-being and public health conditions. Nutritional care in the hospital and other medical settings was scarce. For decades, dietary practices in clinical settings relied on outdated principles. For example, while human nutrition science had already determined the principal nutrients and the notion of daily ratio and calorie needs, patients were still being fed according the ancient principles of an “absolute diet”, ignoring all notions of quantity and quality. Thus, there was a gap in the advancement of knowledge between public health research and the clinical field. In the post-war decades, doctors slowly developed a new interest in and expressed concerns about the feeding of hospitalized patients. Feeding patients in various situations while coping with the progress of surgical techniques and other medical interventions became a real challenge. In fact, such situations, leading to undernutrition, had an impact on morbidity and mortality. In 1932, Cuthbertson had described in detail the metabolic responses of four patients with lower limb injuries [13]. In 1936, the surgeon HO Studley had published a statistical analysis that quantified the relationship between weight loss and mortality. He demonstrated that a reduction of more than 20% of body weight resulted in a postoperative mortality rate of 33%, while a group of patients with a weight loss of less than 20% had a postoperative mortality rate within 3% [14]. In 1947, it was recognized that the quantity and quality of food could distinctly influence the outcome of infectious diseases, surgical or traumatically wounds, burns and blood loss [15]. Thus, the challenge was to feed the patients by any possible route (i.e., oral, enteral or parenteral) to prevent malnutrition and modulate the metabolic response to injury. However, technically the parenteral route was impossible to perform, which triggered extensive research on the subject. In the 1960s, the prevailing dogma was still that ‘‘feeding entirely by vein is impossible; even if
D. Cardenas / Clinical Nutrition ESPEN 11 (2016) e63ee66
it were possible, it would be impractical; and even if it were practical, it would be unaffordable.’’ [16] Such a difficulty was not new: since the description of circulation by William Harvey in the seventeenth century, veins had been imagined as a route of administration for nutrients. Thanks to some significant technical progress, in 1966, Beagle puppies, could be totally fed by the parenteral route for the first time, ensuring the sole nutritional support for growth, development and metabolic support. Two years after that experiment, it became possible for human beings to be fed in the same way. Furthermore, enteral nutrition was developed simultaneously, as risks of hyper-nutrition by the parenteral route and the role of the intestine were being acknowledged (For a complete history of parenteral nutrition see Ref. [16]). Thus, during the 1970s nutrients were no longer only associated with an oral diet, but with artificial means. First, this means that an invasive procedure, either the placement of a catheter for parenteral administration or a tube for enteral nutrition. These techniques are known today as “parenteral/enteral artificial nutrition” and their application as “nutritional support”. Thus, the word “artificial” no longer refers to some food property (the result of a culinary preparation, for instance) as in Hippocratic medicine, but to the particular method of administration and production of nutrients. The second meaning of “artificial” is that nutrients are not the outcome of agronomical production and that their availability does not depend on agricultural policies: nutrients are now the outcome of pharmacological industrial productions. Thus, we may find a wide range of products for nutritional support (i.e., “food for medical purpose”, “nutrition supplement” or “medical foods”). As a result, in both Europe and the United States, products for nutrition support are required to have specific bill regulation with specific legislations and guidelines. Those products are meant for patients with special nutritional needs and health care professionals must deliver indications for nutritional support under medical prescription and supervision. This implies a major change in medical practice since the products of nutrition support are now comparable to the practice in pharmaceuticals [1]. Beside these two meanings, the new concept of the nutrient has undergone another essential transformation, as its function is to reach beyond its nutritional objective. So key nutrients called “immunonutrients” (i.e., glutamine, arginine, citrulline, omega-3) can modulate inflammatory response and help restore immunological and other biological functions. Consequently, nutrients are administered not only for feeding, but to improve host defences and outcomes [17]. The novelty is that we attribute a pharmacological-type action to nutrients, and that they are investigated as such [18]. This aims to guarantee security to the patient, as nutrients must now be assessed under adequate and wellcontrolled clinical investigations, as any new drugs require. 4. Defining clinical nutrition as a science Clinical nutrition can be defined as both an autonomous empirical science and as an art. As an empirical science (i.e. knowledge derived from or guided by experiment), it interacts with other biological science like biochemistry, pharmacology and physiology. Autonomy (i.e. process of a science differentiating itself from other disciplines) can be defined as “a relative independence from other related disciplines, including both ‘sociological’ characteristics, such as the existence of research groups and associations, and ‘epistemological’ characteristics, such as separate methods and theory development” [19]. Table 1 summarizes the epistemological and sociological criteria of clinical nutrition. As an art (i.e. techne, practice), the scientific principles and theories of clinical nutrition are applied through the practice of nutritional care. Nutritional care is a global process that includes
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Table 1 Criteria for disciplinary autonomy of clinical nutrition. Epistemological characteristics A separable research object: The artificial nutrient Separate methods for empirical investigations: pharmaconutrient approach; tracer methodology, etc. An independent theory development or invention of a new theory: Artificial nutrient concept, parenteral and enteral nutrition principles, etc. A common conceptual apparatus: Malnutrition, disease-related malnutrition, immunonutrients, etc. Sociological features A core group of researchers: ESPEN Special interest groups, etc. Common communication channels: Clinical Nutrition Journal, American Journal of Clinical Nutrition, etc. Separate conferences, meetings, etc: ESPEN congress, ASPEN congress, etc. Associations or institutions at a national and/or international level: SFNEP France, SBNC Belgium, DGEM Germany etc. The existence of teaching and training curricula, in addition to courses which are provided at universities or colleges, or offered as commercial courses to trade and industry: LLL ESPEN course, Adriatic Club of Clinical Nutrition (ACCN), etc.
screening, diagnostics, treatments, monitoring and audit in all types of care facilities (hospital, nursing homes and community) [2]. This leads to considering clinical nutrition in the scope of the patient-health care provider interaction in opposite to the organismeenvironment interaction characteristic of human nutritional science (Fig. 1). This has biological, sociological and ethical implications. 5. The domain of clinical nutrition: malnutrition In this context, the domain (a field or scope of knowledge and activity in science) of clinical nutrition can be defined by a series of areas: malnutrition, feeding, metabolism, health and disease. Indeed, clinical nutrition is concerned with all these aspects but there is one that defines it precisely. The main problem addressed by clinical nutrition is malnutrition [20]. This means that clinical nutrition e basic knowledge and practice through nutritional care e is supposed to help fight against malnutrition. Thus, malnutrition is what best defines the domain of knowledge and practice of clinical nutrition. Even if there is some general agreement about the need to fight malnutrition, this concept raises semantic, epistemological and biological controversies. Are malnutrition and undernutrition synonymous? Are malnutrition/undernutrition/obesity to be understood as risk factors or as diseases? How can they be defined biologically, what criteria can be used? There is no consensus. We consider that the term “malnutrition” must not be considered as synonymous with “undernutrition” but as a general term encompassing a wide variety of nutritional statuses: pure starvation, disease-related malnutrition (cachexia), sarcopenia and frailty, as well as overweight, obesity and micronutrient abnormalities. In
Fig. 1. The interdisciplinarity of clinical nutrition.
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that sense, the scope of clinical nutrition must include obesityrelated nutritional and metabolic challenges [21]. The consensus criteria to unify the international terminology published recently by Cederholm T et al. proposes the term “nutritional disorders” as a general term encompassing malnutrition, overnutrition and micronutrient abnormalities and introduce a hierarchical arrangement of the conditions [22]. In our opinion, based on the complexity of those nutritional syndromes, there is no place for this kind of organization. Moreover, “nutritional disorder” (i.e. the absence of order or the state of not being arranged in an orderly manner) and “malnutrition” (i.e. malus bad, badly) can be synonymous in the clinical field, both giving an axiological meaning to the term. Thus there is no place for introducing an extra term that doesn't clarify the nosology of malnutrition. The semantic ambiguities, and the normative and axiological status of concept of malnutrition must be further studied. Efforts should be made to modify the International Classification of Diseases (ICD) coding and the recognition of diverse malnutrition conditions.
malnutrition and disease and relying on a new concept of nutrient. It cannot be subsumed under nutritional science, as it is not to be considered as an organismeenvironment interaction but as an autonomous science, with a proper core of knowledge, domain, and mode of intervention, under the patientehealth care provider interaction. Determining the epistemological status of clinical nutrition may help to consolidate the discipline, face and integrate the ongoing production of knowledge and address the accelerating social, technological, environmental and ethical challenges raised by this science. Statement of authorship Diana Cardenas carried out the study and the whole writing of the manuscript. Conflict of interest There is no conflict of interest to declare.
6. Perspectives for clinical nutrition Statement and funding sources Understanding the epistemological foundation of clinical nutrition may lead to ethical, and academic challenges. First, performing and organizing clinical nutritional care may lead to ethical issues that should be taken into account. This particularly concerns the rationalization and standardization of nutritional care that may question justice and equality in health care. Second, nutritional support involves a multidisciplinary team in care implying the provision of food and drink by mouth econsidered as basic care e but also artificial nutrition legally considered as a treatment. This puts in a constant tension the ethics of care and cure. In that sense, the four ethical elements of care, attentiveness, responsibility, competence and responsiveness, must be placed at the heart of the matter. The bioethical principles of respect of autonomy, non-maleficence, beneficence and justice can be questioned in the practise of nutritional support [23]. The ethics of clinical nutrition must be studied in depth. The recognition of clinical nutrition as an autonomous discipline is a new phenomenon and will inevitably lead to some readjustment of existing professional boundaries. Clinical nutrition is usually subsumed under medical or nutritional-dietetic sciences. Medical students need to attend more courses and training on clinical nutrition, particularly courses on the basics of nutrition, and dieticians need to have more courses and training on clinical nutrition, particularly courses on the basics of medicine. An interdisciplinary speciality must be recognized. This must be a veritable speciality not a subspeciality of gastroenterology or surgery, endocrinology. More research and efforts must be combined to determine consensual core competencies and contents for clinical nutrition. We have proposed a definition of clinical nutrition based on its epistemological status, object and specific domain of knowledge. Clinical nutrition is a basic interdisciplinary and applied science, concerned with malnutrition (under/overnutrition/micronutrient abnormalities). Its aim is to apply the principles of nutritional support (i.e. artificial nutrients) within the framework of nutritional care in order to ensure the nutritional status and modulate other biological functions to positively influence patient treatment and outcome. 7. Conclusion Clinical nutrition is the outcome of a new vision, typical of the twentieth century school of thought: a vision defining the way the patient must be fed, establishing a close relationship between
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