Nutritional care: from the dark ages to the renaissance, to the age of enlightenment
Year: 2009
Type: editorial
Abstract: One of the most extraordinary epidemiological human events occurred in Europe between the mid-19th and mid-20th centuries. In a few decades, life expectancies for all social classes increased significantly, which was paralleled by an increase of the average intelligent quotient. If one were to poll a hundred doctors as to the factors they consider best to explain this astonishing change in human biology, it is likely that the majority would attribute this progress to the scientific and medical advances of that era. Actually, the factor that best explains the increased life expectancy and the enhanced intelligent quotient is improved nutrition [1–3]. Indeed, medical progress had an effect on life expectancy, but its impact occurred when a trend toward improved survival was already evident. These developments provide strong evidence for the crucial role that nutrition plays in our welfare. The converse argument is provided by data from countless human famines [4] and hunger strike studies [5] that documented malnutrition to poor outcome. Adequacy of nutrition is of primacy to the survival of our species. Similarly, an intuitive understanding exists between seriously sick patients who are or became malnourished consequent to their illness and the need to nourish them to enhance their survival. Early examples underscore this point. In 1932, Warren [6] documented that cancer cachexia was a common cause of death in patients with cancer. Similarly, in 1936, Studley [7] made the crucial observation in his gastrectomized patients that the greater the preoperative weight loss in his patients, the higher the complication and mortality rate. These two seminal observations clearly linked nutritional status during illness to outcome. Whether the type of disease and its therapy also plays a role is best illustrated in patients with upper gastrointestinal tumors. They have among the highest incidence of malnutrition that correlates positively with high postoperative complication rates, including death [8]. The complications contributing to their poor outcome are similar to those described by Studley [7] 70 years ago: wound dehiscence, ileus, sepsis, pneumonia, prolonged hospital stay, poor quality of life and death. In the intervening years, numerous studies examined the effects of nutrition therapy, either parenteral or enteral, to decrease disease-related complications. Most commonly, high-risk elective surgical cancer patients were studied. Initially, these studies focused on providing supraphysiological concentrations of different substrates to induce postoperative positive nitrogen balance. The observed reversal of weight loss was due to an increase in fat mass and in total body water. Throughout this time, our concepts in nutrition therapy evolved to include the understanding that specific nutrients had immunological effects, particularly when given in pharmacological amounts. Thus began the era of ‘trial and error’ of immune-enhancing nutrition, not only in cancer patients and high-risk elective surgical patients but also in critically ill postoperative patients. On the basis of our understanding, omega-3 fatty acids exert anti-inflammatory effects and reduce costs when their use is integrated into surgical care [9]. Glutamine influences the expression of many genes, and its clinical benefits remain to be completely elucidated [10]. By further understanding the specific molecular effects of each nutrient, it will be possible to combine nutrients in correct proportion to tailor the therapeutic needs of managing critically ill patients. The ‘immune enhancing nutritional mixtures’ that in the past were added to conventional substrates known to improve metabolic processes included arginine, glutamine, nucleotides, antioxidants and omega-3 fatty acids often in different permutations. It required a meta-analysis of many studies to conclude that immune-enhancing nutrition improved clinical outcomes. In retrospect, it may seem curious that for almost 20 years, studies were done in which different experimental compounds were administered simultaneously in an effort to determine the nebulous postoperative beneficial metabolic effects. But at the time, such was our knowledge base, the sense of frustration and urgency that underpinned the need to address ongoing critical issues as to which ‘immune compounds’ and in what amounts were needed to reverse the processes of cancer cachexia. Despite the advancements in better understanding the role of nutritional support in the comprehensive management of patients, the level of nutritional care across the world is frequently suboptimal. The good news is that the tide is turning! Malnutrition is now being included in the political agenda, in order to develop and implement at effective programmes of nutritional screening and intervention worldwide. In so doing, we are now facing a new and confounding as well as an unforeseen event: ‘obesity pandemic’. Could this diagnosis prevent the universal acknowledgement of malnutrition and its subsequent need for nutritional therapy? The increasing prevalence of obesity may profoundly alter the phenotype of malnutrition to which we are accustomed. As an example, it is progressively more frequent to diagnose cancer patients with sarcopenic obesity rather than with the ‘old style’ cachexia, as documented above [6–8]. Therefore, disease-associated nutritional depletion may not be so apparent, and patients may not be considered eligible for nutritional intervention. To cope with this possible problem, nutritional care is progressively changing, and metabolic support is progressively stemming from nutritional support. As in the era of enlightenment, experimental and clinical studies revealed the pathogenic mechanisms of a number of biological events, including those of disease-associated malnutrition. Scientific evidence helped to understand the role of specific nutrients in preventing and treating chronic diseases and by targeting molecular pathways of pathogenic mechanisms. Chronic inflammatory states, neurochemical derangements leading to anorexia, muscle protein catabolism and impaired glucose homeostasis represent pathogenic mechanisms that might be counteracted by the selective and early use of pharmaconutrients. It is important to stress that metabolic support should never replace nutritional support. Indeed, although discussing the potential benefits of specific pharmaconutrients, many patients to date still do not receive adequate amounts of macronutrients, and it has been demonstrated that inhibiting muscle proteolysis without providing adequate amounts of nutrients, paradoxically, results in exacerbation of muscle catabolism. On the contrary, it is envisaged that metabolic support will integrate drug therapy, as biologically active nutrients may induce specific genes that reduce toxicity and enhance efficacy of therapeutic strategies. After a long journey, nutritional care has emerged from the Dark Ages and is now entering the Renaissance era, but its further development is not ensured. Further studies and better knowledge of human biology are needed to prevent our return to the Middle Ages and promote the start of the age of enlightenment.
Language: English
Subfield: Nutrition and Dietetics
Field: Nursing
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2032940290