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Nutrition Expert Articles

Welcome to Nutrition Expert Articles - Nestlé Health Science's educational resource where clinicans can read about current topics, authored by leading nutrition experts.

Robert Martindale MD, PhD
Professor of Surgery
Oregon Health and Science University
Portland, Oregon

Traditionally, nutrients have been viewed as a means to provide humans with basic calories to maintain homeostasis. Of these, fat has been the substrate that provides the most concentrated source of calories, while providing essential fatty acids and assisting in the luminal absorption of fat soluble vitamins.

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Other Recent Nutrition Topics:

Role of Omega-3 Fatty Acids in Modulating Inflammation: Is It Time for Routine Use?

Traditionally, nutrients have been viewed as a means to provide humans with basic calories to maintain homeostasis. Of these, fat has been the substrate that provides the most concentrated source of calories, while providing essential fatty acids and assisting in the luminal absorption of fat soluble vitamins.

Peptides: A Review of the Benefits

For patients with impaired digestion or absorption, research suggests that peptide-based formulas have numerous potential advantages over intact protein or free amino acid formulas.

The Role of Whey Protein in Nutritional Therapy

The number of children with special health care needs is increasing due to medical advances, early disease identification and improved nutritional interventions. Children with special health care needs often require individualized nutrition care in order to grow and develop to their full potential. This article will identify common nutrition challenges and highlight nutrition assessment parameters used in evaluating children with special healthcare needs, particularly those children with developmental delays. The potential benefits of whey-based formulas in the nutritional management of this population are then presented.

Applying What we Know about Nutrition to Pressure Ulcer Prevention in Hospitals

Clinicians may anticipate increased interest in the role of food and nutrient intake relative to a pressure ulcer prevention protocol. A review of current guidelines does not reveal specific nutrient recommendations as part of a pressure ulcer prevention protocol other than to optimize nutrient intake for those who have inadequate intake. Refining screening and referral systems to identify patients who would benefit from nutrition intervention, then optimizing nutrient intake may prove beneficial.

Body Composition (Sarcopenia) in Obese Patients: Implications for Care in the Intensive Care Unit

The study of body composition is a rapidly evolving science. In today’s environment, there is a great deal of interest in assessing body composition, especially in the obese subject, as a guide to clinical and nutrition interventions. There are some strikingly different compartments of body composition between the obese and the lean patient. We do have the ability to measure body composition accurately, although these techniques can be labor intensive and expensive. The recognition of patients with sarcopenic obesity has identified a potential high-risk patient population. These body composition abnormalities may have even greater importance in the intensive care patient.

Current Strategies of Critical Care Assessment and Therapy of the Obese Patient (Hypocaloric Feeding): What Are We Doing and What Do We Need to Do?

Two of the most challenging issues in the clinical management of the obese patient are assessing energy requirements and whether hypocaloric (permissive) underfeeding should be employed. Multiple predictive equations have been used in the literature to estimate resting metabolic rate, although no consensus has emerged regarding which prediction equation is most accurate and precise in the obese population. Hypocaloric, or permissive underfeeding, specifically refers to the intentional administration of calories that are less than predicted energy expenditure. Thus far, very few studies performed have been performed to assess the efficacy of hypocaloric feeding in the obese hospitalized patient. It is concluded that the optimal caloric intake of obese patients in the intensive care unit remains unclear given the limitation of the existing data.

Nutrition Therapy in the Critically Ill Patient With Obesity

Obesity compounds the metabolic response to critical illness and augments the consequences of overfeeding. Effective monitoring is essential for the prevention of, or to avoid, worsening of preexistent morbidities associated with obesity during the implementation of specialized nutrition support. This monitoring should guide the clinician toward the selection of appropriate therapeutic options to reduce complications from significant hyperglycemia, dyslipidemia, hypercapnia, fluid overload, and worsening of hepatic steatosis. Conventional nutrition outcome markers should be employed, with their limitations understood, when used for the critically ill obese patient.

Gut Microbiota, Intestinal Permeability, Obesity-Induced Inflammation, and Liver Injury

Obesity and its metabolic complications are major health problems in the United States and worldwide, and increasing evidence implicates the microbiota in these important health issues. Indeed, it appears that the microbiota function much like a metabolic “organ,” influencing nutrient acquisition, energy homeostasis, and, ultimately, the control of body weight. Moreover, alterations in gut microbiota, increased intestinal permeability, and metabolic endotoxemia likely play a role in the development of a chronic low-grade inflammatory state in the host that contributes to the development of obesity and associated chronic metabolic diseases such as nonalcoholic fatty liver disease. Supporting these concepts are the observations that increased gut permeability, low-grade endotoxemia, and fatty liver are observed in animal models of obesity caused by either high-fat or high-fructose feeding. Consistent with these observations, germ-free mice are protected from obesity and many forms of liver injury. Last, many agents that affect gut flora/permeability, such as probiotics/prebiotics, also appear to affect obesity and certain forms of liver injury in animal model systems. Here the authors review the role of the gut microbiota and metabolic endotoxemia-induced inflammation in the development of obesity and liver injury, with special reference to the intensive care unit setting.

Obesity—A Growing Frontier in Nutrition Support


Obesity Epidemic: Overview, Pathophysiology, and the Intensive Care Unit Conundrum

Obesity is one of the leading causes of preventable death in the United States, second only to smoking. The annual number of deaths attributed to obesity is estimated to be as high as 400,000. Nearly 70% of the adult U.S. population is overweight or obese. The historical viewpoint toward obesity has deemed it to be a lifestyle choice or characterological flaw. However, given the emerging research into the development of obesity and its related complications, our perspective is changing. It is now clear that obesity is a heterogeneous disease with many different subtypes, which involves an interplay between genetic and environmental factors. The current epidemic of obesity is the result of an obesogenic environment (which includes energy-dense foods and a lack of physical activity) in individuals who have a genetic susceptibility for developing obesity. The pathophysiology associated with weight gain is much more complex than originally thought. The heterogeneous nature of the disease makes the development of treatment strategies for obesity difficult. Obesity in general is associated with increased all-cause mortality and cause-specific mortality (from cardiovascular, diabetic, hepatic, and neoplastic causes). Yet despite increased overall mortality rates, current evidence suggests that when these same patients are admitted to the intensive care unit (ICU), the obesity provides some protection against mortality. At present, there is no clear explanation for this obesity conundrum in critical illness.

The Outcomes of Obese Patients in Critical Care

The severity and prevalence of obesity continue to rise throughout the world. A similar rise in the prevalence of obesity is seen in the population of patients admitted to the intensive care unit (ICU). In the ICU setting, nearly every aspect of care is made more difficult by obesity. This review highlights the challenges in the care of obese ICU patients. Multiple statistical reviews have suggested improved outcomes for obese ICU patients. This article critically evaluates published outcome studies and highlights potential confounders that may result in misleading results. Body mass index (BMI) has been traditionally used to stratify risk in obese populations. Other factors that may be more predictive of poor outcomes in obese populations are further discussed. Further research in these factors has the potential to guide therapy in high-risk critically ill obese populations.

Nutrition and Metabolic Complications After Bariatric Surgery and Their Treatment

The increase in the number of bariatric procedures annually suggests that these patients will constitute an increasing portion of obese patients who require hospital and intensive care. Currently, little prospective information is available regarding the course of bariatric surgery patients requiring intensive care. Knowledge of the type of bariatric operation performed and an understanding of its anatomy and physiology are useful to provide optimal care to these patients, particularly when considering potential nutrition complications and their diagnosis and treatment. In this article, the authors describe nutrition problems that may be present and potentially affect the course of a hospitalized and/or critically ill patient who has previously undergone a bariatric operation.

Pharmaconutrition for the Obese, Critically Ill Patient

Obesity is an epidemic that affects approximately 30% of the adult population in the United States. The prevalence of obesity in the critically ill seems to correlate with the rise in obesity in the general population. Delivery of standard enteral nutrition (EN) to patients in the intensive care unit (ICU) has been shown to decrease infectious complications. Obese ICU patients may be at increased risk for infections, ICU length of stay, and ventilation requirements compared to the nonobese. Pharmaconutrition has been shown to decrease many of these negative ICU outcomes. Because of obesity-associated increased ICU risk, provision of certain pharmaconutrients should be considered in obese patients requiring EN therapy. This review examines the evidence for specific nutrients such as green tea, curcumin, sulforaphane, poly-unsaturated fatty acids, L-arginine, L-citrulline, L-leucine, protein, probiotics, magnesium, medium-chain triglycerides, and zinc for the treatment of obesity. These nutrients could potentially be added to current EN formulas or provided as supplements.

Issues Involved in the Process of Developing a Medical Food

The creation of a medical food with potential health benefits for a particular patient population is a surprisingly complex process. Fortunately, the developmental process for a specific medical food is not as rigorous or as tightly regulated as that of a pharmaceutical agent. However, numerous factors unique to the enteral formulation of a new product come into play, such as physical/chemical compatibility, pH, stability, bioavailability, decay, and even palatability. Additional considerations such as strength of health benefit claims, packaging or presentation, and marketability determine the ultimate commercialization and whether a product ends up being released to the public. A full understanding of the development, substantiation, and commercialization of a medical food is necessary for important physiologic concepts in nutrition therapy to end up as part of the therapeutic regimen at the bedside of the critically ill obese patient.

Nutrition Delivery for Obese ICU Patients: Delivery Issues, Lack of Guidelines, and Missed Opportunities

The most appropriate enteral formula for the severely obese population has yet to be determined. The obese patient in the intensive care unit (ICU) creates numerous difficulties for managing care, one being the ability to deliver appropriate and timely nutrition. Access for nutrition therapy, either enteral or parenteral, can also create a challenge. Currently, no specific guidelines are available on a national or international scale to address the issues of how and when to feed the obese patient in the ICU. A bias against feeding these patients exists, secondary to the perception that an enormous quantity of calories is stored in adipose tissue. Making a specialty enteral formula for obesity from existing commercial formulas and other modular nutrient components is not practical, secondary to difficulty with solubility issues, dilution of the formula, and safety concerns. Using today’s concepts and current metabolic data, a formula could be produced that would address many of the specific metabolic derangements noted in obesity. This formula should have a high-protein, low-carbohydrate content with at least a portion of the lipid source coming from fish oil. Specific nutrients that may be beneficial in obesity include arginine, glutamine, leucine, L-carnitine, lipoic acid, S-adenosylmethionine, and betaine. Certain trace minerals such as magnesium, zinc, and selenium may also be of value in the obese population. The concept of a specific bariatric formulation for the ICU setting is theoretically sound, is scientifically based, and could be delivered to patients safely.

Nutrition Therapy of the Severely Obese, Critically Ill Patient: Summation of Conclusions and Recommendations

This report compiles the conclusions and recommendations for nutrition therapy of the obese, critically ill patient derived by the group of experts participating in this workshop on obesity in critical care nutrition. The recommendations are based on consensus opinions of the group after review of the current literature. Obesity clearly adds to the complexity of nutrition therapy in the intensive care unit (ICU). Obesity alters the incidence and severity of comorbidities, tolerance of the prescribed regimen, and ultimately patient outcome through the course of hospitalization. Although the basic principles of critical care nutrition apply to the obese ICU patient, a high-protein, hypocaloric regimen should be provided to reduce the fat mass, improve insulin sensitivity, and preserve lean body mass. The ideal enteral formula should have a low nonprotein calorie to nitrogen ratio and have a variety of pharmaconutrient agents added to modulate immune responses and reduce inflammation.