Protein sparing therapy during periods of starvation with sepsis of trauma

Current perspectives in obesity management: unraveling the impact of different therapy approach in real life obesity care

BACKGROUND

The challenge of addressing obesity persists in healthcare, necessitating nuanced approaches and personalized strategies. This study aims to evaluate the effects of diverse therapeutic interventions on anthropometric and biochemical parameters in individuals with overweight and obesity within a real-world clinical context.

METHODS

A retrospective analysis was conducted on 192 patients (141 females, 51 males) aged 18 to 75, with a BMI ranging from 25 to 30 (14.1%) and BMI ≥ 30 (85.9%), observed over a 12-month period at our Endocrinology Unit. Treatment cohorts comprised individuals following different regimens: Mediterranean Diet (MD), with an approximate daily intake of 1500 kcal for women and 1800 kcal for men (71% patients); Ketogenic Diet (KD), utilizing the VLCKD protocol characterized by a highly hypocaloric dietary regimen < 800 kcal/day (14% patients); metformin, administered using the oral formulation (5% patients); pharmacological intervention with GLP1-RA administered via subcutaneous injection with incremental dosage (10% patients). Supply constraints limited the efficacy of Liraglutide, whereas Semaglutide was excluded from comparisons due to its unavailability for obesity without diabetes. Blood tests were conducted to assess lipid profile, glycemic profile, and anthropometric parameters, including BMI, waist circumference, and waist-to-height ratio.

RESULTS

Significant BMI changes were observed from baseline to 6 months across MD, KD, and Liraglutide groups (p < 0.05). KD exhibited notable reductions in waist circumference and waist-to-height ratio within the initial quarter (p < 0.05), with a significant triglyceride decrease after 6 months (p < 0.05), indicating its efficacy over MD. Liraglutide demonstrated a substantial reduction in HbA1c levels in the first quarter (p < 0.05). During the first three months, the ANOVA test on fasting blood glucose showed a statistically significant impact of the time variable (p < 0.05) rather than the specific treatments themselves (Liraglutide and KD), suggesting that adherence during the early stages of therapy may be more critical than treatment choice.

CONCLUSIONS

Positive outcomes from targeted interventions, whether pharmacological or dietary should encourage the exploration of innovative, long-term strategies that include personalized treatment alternation. The absence of standardized protocols underscores the importance of careful and tailored planning in managing obesity as a chronic condition.

The Real-Life Use of a Protein-Sparing Modified Fast Diet by Nasogastric Tube (ProMoFasT) in Adults with Obesity: An Open-Label Randomized Controlled Trial

BACKGROUND

Protein-sparing modified fast (PSMF) diet is a very-low-carbohydrate ketogenic diet administered to patients with obesity, which preserves lean mass and suppresses appetite as well as continuous enteral feeding. Thus, we aim to evaluate the effect of the PSMF diet administered continuously by nasogastric tube (NGT) or orally.

METHODS

Patients with a body mass index (BMI) > 34.9 kg/m2 were randomly assigned to receive a whey protein PSMF formula through NGT (ProMoFasT) or orally. Data were collected at baseline and after 150 days. The endpoints were assessed in the intention-to-treat population.

RESULTS

We enrolled 20 patients in the ProMoFasT group and 24 in the oral group. No differences in body weight, BMI or waist circumference between the two groups were found after 150 days. At follow-up, FFM (%) and MM (%) results were higher in the ProMoFasT group than the oral group (63.1% vs. 52.9%, p = 0.012 and 45.0% vs. 36.1%, p = 0.009, respectively) and FM (kg) and FM (%) were significantly lower in the ProMoFasT group (36.9 kg vs. 44.0 kg, p = 0.033 and 37.4% vs. 44.9%, p = 0.012, respectively). Insulin levels were lower in the ProMoFasT group than the oral group at follow-up (11.8 mU/L vs. 28.0 mU/L, p = 0.001, respectively).

CONCLUSION

The ProMoFasT is more effective in improving body composition and glucometabolic markers than the same diet administered orally.

Effects of ketone bodies on energy expenditure, substrate utilization, and energy intake in humans

The potential of ketogenic approaches to regulate energy balance has recently gained attention since ketones may influence both energy expenditure and energy intake. In this narrative review, we summarized the most relevant evidence about the role of ketosis on energy expenditure, substrate utilization, and energy intake in humans. We considered different strategies to induce ketosis, such as fasting, dietary manipulation, and exogenous ketone sources. In general, ketosis does not have a major influence on energy expenditure but promotes a shift in substrate utilization towards ketone body oxidation. The strategies to induce ketosis by reduction of dietary carbohydrate availability (e.g., ketogenic diets) do not independently influence energy intake, being thus equally effective for weight loss as diets with higher carbohydrate content. In contrast, the intake of medium-chain triglycerides and ketone esters induces ketosis and appears to increase energy expenditure and reduce energy intake in the context of high carbohydrate availability. These latter strategies lead to slightly enhanced weight loss. Unfortunately, distinguishing the effects of the various ketogenic strategies per se from the effects of other physiological responses is not possible with the available human data. Highly controlled, inpatient studies using targeted strategies to isolate the independent effects of ketones are required to adequately address this knowledge gap.

The ketogenic diet corrects metabolic hypogonadism and preserves pancreatic ß-cell function in overweight/obese men: a single-arm uncontrolled study

BACKGROUND

Overweight and obesity are increasingly spread in our society. Low testosterone levels are often present in these patients, the so-called metabolic hypogonadism, that further alters the metabolic balance in a sort of vicious cycle. Very low-calorie ketogenic diet (VLCKD) has been reported to efficiently reduce body weight, glycaemia, and the serum levels of insulin, glycated hemoglobin, but its effects on β-cell function and total testosterone (TT) levels are less clear.

AIM

To evaluate the effects of VLCKD on markers suggested to be predictive of β-cell dysfunction development, such as proinsulin or proinsulin/insulin ratio, and on TT values in a cohort of overweight or obese nondiabetic male patients with metabolic hypogonadism.

METHODS

Patients with overweight or obesity and metabolic hypogonadism underwent to VLCKD for 12 weeks. Anthropometric parameters, blood testing for the measurement of glycaemia, insulin, C-peptide, proinsulin, TT, calculation of body-mass index (BMI), and HOMA index were performed before VLCKD and after 12 weeks.

RESULTS

Twenty patients (mean age 49.3 ± 5.2 years) were enrolled. At enrollement all patients presented increased insulin, HOMA index, C-peptide, and proinsulin levels, whereas the proinsulin/insulin ratio was within the normal values. After VLCKD treatment, body weight and BMI significantly decreased, and 14.9 ± 3.9% loss of the initial body weight was achieved. Glycaemia, insulin, HOMA index, C-peptide, and proinsulin significantly decreased compared to pre-VLCKD levels. Serum glycaemia, insulin, C-peptide, and proinsulin levels returned within the normal range in all patients. No difference in the proinsulin/insulin ratio was observed after VLCKD treatment. A mean increase of 218.1 ± 53.9% in serum TT levels was achieved and none of the patients showed TT values falling in the hypogonadal range at the end of the VLCKD treatment.

CONCLUSIONS

This is the first study that evaluated the effects of VLCKD on proinsulin, proinsulin/insulin ratio, and TT levels. VLCKD could be safely used to improve β-cell secretory function and insulin-sensitivity, and to rescue overweight and obese patients from β-cell failure and metabolic hypogonadism.

Very-low-calorie ketogenic diet (VLCKD) in the management of metabolic diseases: systematic review and consensus statement from the Italian Society of Endocrinology (SIE)

BACKGROUND

Weight loss is a milestone in the prevention of chronic diseases associated with high morbility and mortality in industrialized countries. Very-low calorie ketogenic diets (VLCKDs) are increasingly used in clinical practice for weight loss and management of obesity-related comorbidities. Despite evidence on the clinical benefits of VLCKDs is rapidly emerging, some concern still exists about their potential risks and their use in the long-term, due to paucity of clinical studies. Notably, there is an important lack of guidelines on this topic, and the use and implementation of VLCKDs occurs vastly in the absence of clear evidence-based indications.

PURPOSE

We describe here the biochemistry, benefits and risks of VLCKDs, and provide recommendations on the correct use of this therapeutic approach for weight loss and management of metabolic diseases at different stages of life.

Protein requirements, morbidity and mortality in critically ill patients: fundamentals and applications

Recent evidence suggests that a negative protein balance secondary to severe disease is associated with increased morbidity. A loss of total body protein is inevitable in this scenario, even with an aggressive nutritional approach, primarily due to the catabolism of skeletal muscle fibers. The ubiquitin-proteasome system is the primary metabolic and biochemical mechanism involved in this process; paradoxically, this system consumes adenosine triphosphate as its energy source. It is possible that a neutral protein balance in these clinical situations is important for improving outcomes and achieving the caloric goals estimated or measured by indirect calorimetry. Recent studies have suggested that the use of higher protein concentrations in nutritional therapy for critically ill patients may help to reduce mortality. The purpose of this study was to review some of the nutrition therapy principles related to protein metabolism, evaluate the main assertions of the guidelines of specialty societies and review the recent studies that address these issues using critical insights from the authors' clinical experience.

Ketogenic enteral nutrition as a treatment for obesity: short term and long term results from 19,000 patients

Background

Only protein diet has been used successfully to prevent loss of lean body mass first in post-surgical and then in obese patients. We studied overweight and obese patients receiving short treatments of an exclusively protein-based nutritional solution as 24-hour enteral infusion.

Methods

19,036 patients (age 44.3 ± 13, M:F = 2:5) with an initial body mass index of 36.5 ± 7.1 underwent 10-day cycles of enteral nutrition through a fine nasogastric tube. The nutritional solution consisted solely of 50–65 g of proteins, plus vitamins and electrolytes. The 24-hour infusion was controlled with a small portable pump. Before and after each 10-day cycle body composition was checked with a Handy 3000 impedance analyzer. At the onset of treatment, average fat mass was 40.9 ± 12.8 kg while body cell mass was 42.7 ± 7.2 kg in males and 27.4 ± 4.6 kg in females.

Results

After an average of 2.5 cycles the patients lost 10.2 ± 7.0 kg of body weight, 5.8 ± 5.5 kg of fat mass and 2.2 ± 3.3 kg of body cell mass. No significant adverse effects were recorded except asthenia and constipation which were easily controlled with therapy. Long-term results were obtained from 15,444 patients and after an average of 362 ± 296 days we found a mean weight regain of 15.4%.

Conclusion

Ketogenic Enteral Nutrition treatment of over 19,000 patients induced a rapid 10% weight loss, 57% of which was Fat Mass. No significant adverse effects were found. The treatment is safe, fast, inexpensive and has good one-year results for weight maintenance.

Losing weight without dieting. Use of commercial foods as meal replacements for lunch produces an extended energy deficit

High-protein liquid meal replacements have proven to be effective in reducing caloric intake and body weight. Recently, substituting high fiber breakfast cereals for the more expensive high-protein drinks has been found to be equally effective to reduce weight. The following study tested the hypothesis that the mechanism responsible for the reduced intake was not the dietary composition of the meal replacement, but the controlled portion sized meals. Seventeen volunteers ate all of their meals and snacks from foods provided by the research unit from Monday to Friday for five consecutive weeks. For the first week, all participants selected their food from a buffet where each food was weighed before and after eating. For the next two weeks, half of the group selected their lunch by choosing one food from a selection of six commercially available portion controlled foods. They could eat as much as they wished at other meals or snacks. For final weeks four and five, the conditions were reversed for the two groups. Consuming the portion controlled lunches resulted in about a 250 kcal reduction in energy intake. More importantly, no sign of caloric compensation was evident across the 10 days of testing, an observation substantiated by a significant loss of body weight. The results suggest that the mere substitution of one smaller portioned meal each day is sufficient to cause reduction in daily energy intake and a significant amount of weight.

Cachexia, malnutrition, the refeeding syndrome, and lessons from Goldilocks

Cachexia has plagued clinicians for centuries. Although all cachexia is related to malnutrition, cachexia associated with malignant diseases differs from starvation cachexia in that it is more recalcitrant to nutritional therapy. All cachexia responds to judicious nutritional support; however, cancer cachexia worsens autonomously as the disease advances and cannot be arrested or reversed by any known form of nutrition, hormonal, or pharmacologic therapy. Cachexia must be treated cautiously to avoid overfeeding syndrome, which may result in serious or dangerous complications or death.

Effect of intraoperative acetated Ringer's solution with 1% glucose on glucose and protein metabolism

PURPOSE

To investigate the effects of the intraoperative administration of Ringer's solution with 1% glucose on the metabolism of glucose, lipid and muscle protein during surgery.

METHODS

Thirty-one adult patients, American Society of Anesthesiologists physical status I or II, undergoing elective otorhinolaryngeal, head and neck surgeries were randomly assigned to one of two patient groups: those receiving acetated Ringer's solution with 1% glucose (Group G) or those receiving acetated Ringer's solution without glucose (Group R) throughout the surgical procedure. Plasma glucose was measured at anesthetic induction (T0), artery 1 h (T1), 2 h (T2), 3 h after anesthetic induction (T3) and at the end of surgery (T4). Plasma ketone bodies, insulin and 3-methylhistidine were measured at T0 and T4.

RESULTS

The intravenous infusion for patients in Group G and R was 6.1 + or - 0.8 and 6.3 + or - 1.7 ml/kg/h, respectively, with Group G patients receiving a dose of 4.1 g/h glucose. Plasma glucose levels were significantly higher in Group G than in Group R patients at T1, T2, T3 and T4; however, plasma glucose remained <150 mg/dl in both groups. The plasma concentration of ketone bodies was significantly higher (P < 0.05) in Group R than in Group G patients at T4. Changes in plasma 3-methylhistidine concentration was significantly lower in Group G than in Group R patients. These results indicate that acetated Ringer's solution with 1% glucose decreased protein catabolism without hyperglycemia among the Group G patients.

CONCLUSION

The infusion of a small dose of glucose (1%) during minor otorhinolaryngeal, head and neck surgeries may suppress protein catabolism without hyperglycemia and hypoglycemia.

Restoration of body energy reserves during refeeding in rats is dependent on both the intensity of energy restriction and the metabolic status at the onset of refeeding [corrected]

During starvation, after a short dynamic period of adaptation (phase I), a metabolic steady state is reached in which proteins are spared and lipids provide most of the energy expended [phase II (P2)]. However, protein breakdown increases dramatically once a lower threshold of body lipids is reached [phase III (P3)]. Body composition, energy intake, energy expenditure, and energy efficiency were determined in 8 groups of rats (fed, food-deprived up to P2 or P3 of starvation and refed for 3 d, 7 d, or until body mass restoration) to determine whether the kinetics of lipid and/or protein reserve recovery may be slowed down when refeeding occurs after the lipid threshold has been reached. Despite larger losses, P3 refed rats restored their body reserves as efficiently as those refed in P2. Whatever the nutritional status at the onset of refeeding, rehydration occurred first and hyperphagia played a more important role than hypometabolism in the restoration of the lost reserves. However, the pattern of body component gains was different during early refeeding. In P3 refed rats, body lipids were restored preferentially by significant contribution from endogenous lipid production. Thus, the extent of lipid depletion has important consequences for the restoration pattern of the body reserves. It depends not only on the intensity of the energy restriction (partial or total) as already demonstrated but also on the metabolic status at the onset of refeeding. These results may have significant implications on the way refeeding should be conducted after severe energy depletion.

Protein and energy provision in critical illness

It has recently been recommended that parenterally fed, critically ill patients should receive considerably less energy than the 36 kcal.kg(-1).d(-1) customarily received in earlier years and that mixed amino acid infusions not exceed 1.5 g.kg(-1).d(-1). The implications of these recommendations should be considered carefully, especially for patients with low body weight. Any sizeable reduction in energy provision will lead to negative energy balance in at least some patients, and negative energy balance is known to increase protein requirements. The optimal rate of amino acid delivery for underfed, critically ill patients is not well defined and could well exceed 1.5 g.kg(-1).d(-1). In addition, there are good reasons to suspect that the safe protein requirement of severely underweight, critically ill patients is >1.5 g.kg(-1).d(-1), even when adequate energy is provided.

Very-low-calorie diets and sustained weight loss

OBJECTIVE

To review of the literature on the topic of very-low-calorie diets (VLCDs) and the long-term weight-maintenance success in the treatment of obesity.

RESEARCH METHODS AND PROCEDURES

A literature search of the following keywords: VLCD, long-term weight maintenance, and dietary treatment of obesity.

RESULTS

VLCDs and low-calorie diets with an average intake between 400 and 800 kcal do not differ in body weight loss. Nine randomized control trials, including VLCD treatment with long-term weight maintenance, show a large variation in the initial weight loss regain percentage, which ranged from -7% to 122% at the 1-year follow-up to 26% to 121% at the 5-year follow-up. There is evidence that a greater initial weight loss using VLCDs with an active follow-up weight-maintenance program, including behavior therapy, nutritional education and exercise, improves weight maintenance.

CONCLUSIONS

VLCD with active follow-up treatment seems to be one of the better treatment modalities related to long-term weight-maintenance success.

A pilot study of protein sparing in healthy dogs using peripheral parenteral nutrition

Total parenteral nutrition is the standard nutritional support of dogs when the enteral route is contraindicated, but it can be difficult because of cost, technical difficulties, and potential complications. Peripheral parenteral nutrition (PPN) may be a feasible option for short-term support in some cases. The objectives of this study were to determine the effect of PPN on nitrogen balance (as an indicator of the effect on protein sparing), serum folate concentrations and serum insulin-like growth factor-I (IGF - I) concentrations in fasting dogs. The effect of PPN on these parameters has not previously been reported in dogs. Using a cross-over design, three healthy adult fasting dogs were randomly assigned to three treatments: 5 per cent amino acid solution, 5 per cent glucose solution, and a control electrolyte solution. The solutions were administered into a peripheral vein at 60 ml kg(-1)per day for 4 days. The amino acid infusion resulted in a positive nitrogen balance and the glucose infusion produced less nitrogen loss than the control. Amino acid, but not glucose or electrolyte infusions, decreased serum folate concentrations. Amino acid and glucose infusions resulted in higher serum IGF -I concentrations than electrolyte infusions, although the differences were small and IGF -I decreased in all cases. In conclusion, these findings suggest that PPN increases nitrogen balance in healthy dogs undergoing short-term fasting.

Effects of intraoperative glucose administration on circulating metabolites and nitrogen balance during prolonged surgery

STUDY OBJECTIVES

To compare the effects of intraoperative administration of 2.5% glucose or Ringer's solution on metabolism during prolonged surgery.

DESIGN

Prospective, randomized study.

SETTING

Teaching hospital.

PATIENTS

20 ASA physical status I and II adults patients scheduled for thoracic or abdominal surgery lasting at least 3 hours.

INTERVENTIONS

Patients received Ringer's solution (Group R) or 2.5% glucose solution (Group G) 10 ml.kg-1.h-1 during surgery and 2 ml.kg-1.h-1 during the first two postoperative hours (Ringer's or glucose), then 40 ml.kg-1.day-1 of 5% intravenous (i.v.) glucose postoperatively.

MEASUREMENTS AND MAIN RESULTS

Plasma glucose, free fatty acids, ketone bodies, lactate, insulin, glucagon, cortisol, and growth hormone concentrations were determined after an overnight fast (T0), on induction of anesthesia (T1), at the end of surgery (T2), 2 hours thereafter (T3), and on the following morning (T4). Capillary blood glucose was determined every 30 minutes from T1 to T2. Urinary nitrogen and 3-methylhistidine were measured every day for 5 days. There were no differences between groups in demographic data, anesthesia, or surgical procedures. All data were comparable at baseline and on the following morning. In Group R, no patient experienced hypoglycemia, but plasma fatty acids and ketone bodies increased during surgery. In Group G, glycemia rose to very high levels, with a significant increase in insulin during surgery. Other hormones were the same within the two groups. Urinary nitrogen and 3-methylhistidine were similar in both groups.

CONCLUSION

The absence of glucose infusion in prolonged surgery did not cause hypoglycemia, and no increase in protein catabolism was observed.

Study of hypocaloric peripheral parenteral nutrition in postoperative patients (Europan project)

The objective of this study is to ascertain whether or not the supply of a low-calorie amino acids (AA) parenteral solution is useful in postoperative patients, by assessing a series of parameters that indicate nutritional status. 75 postoperative patients who met at least 2 of the 3 criteria: 1) albumin less than 3 g/dl; 2)prealbumin less than 21 mg/dl; 3) body weight less than 95% of ideal weight, were studied. Patients were divided into 4 groups: control group, 15 patients receiving conventional infusion therapy; group I, 20 patients receiving glucose + AA; group II, 20 patients receiving glycerol + AA; and group III, 20 patients receiving sorbitol-xylitol + AA. The most significant findings were a prompt recovery of short half-life proteins (prealbumin and retinol binding protein), a less negative nitrogen balance, a greater decrease in urinary 3-methylhistidine and a marked increase in most AAs when hypocaloric peripheral parenteral nutrition (HPPN) was used. As regards complications, suture dehiscence occurred in a greater percentage of control patients than in the active therapy groups (13.3% versus 5%) and, in contrast, a greater number of cases of infusion phlebitis was observed in the HPPN groups. Clinical data were not statistically significant. We conclude that HPPN is a valid means for providing nutritional support but, at present, there are few randomized, controlled studies that show that its use is clearly beneficial.

The importance of a source of sufficient protein in postoperative hypocaloric partial parenteral nutrition support

A comparison of postoperative metabolic and nutritional responses to different hypocaloric parenteral nutrition supports was performed in 42 patients with various gastric lesions. Sixteen patients (group A) received 3000 mL of a 5% glucose in water or glucose in saline infusion per day after surgery (approximately 10 kcal/kg per day). Another 14 patients (group B) received 2000 mL of 5% glucose in water or saline plus 1000 mL of 5% amino acid solution per day (approximately 10 kcal/kg per day and 1 g of protein per kilogram per day). The other 12 patients (group C) received 2000 mL of 5% glucose in water or saline plus 500 mL of 5% amino acid solution and 500 mL of 10% fat emulsion (approximately 20 kcal/kg per day and 0.5 g of protein per kilogram per day). After 7 days of study, all three groups were found to have a decrease in body weight, mid-arm circumference, triceps skin-fold, and serum albumin level, and the differences among them were not significant. Groups B and C had significantly less negative mean nitrogen balance than group A (-5.54 +/- 0.63 g/d and -6.07 +/- 0.49 g/d vs -9.20 +/- 0.68 g/d). Group B also had a significantly greater increase of transferrin (from 175.5 +/- 9.9 mg/dL to 185.4 +/- 9.3 mg/dL) than group A and a significantly greater increase in total lymphocyte count (from 956 +/- 113 cells/mm3 to 1196 +/- 176 cells/mm3) than groups A and C.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective study on the efficacy of branched-chain amino acids in septic patients

The metabolic response to sepsis is characterized by increased proteolysis and gluconeogenesis, reduced protein synthesis, and negative nitrogen balance. The effects of a solution with a high proportion of branched-chain amino acids (BCAA) on the nutritional state of septic patients were evaluated. Eighty patients with peritonitis were divided into two groups of 40 patients; group 1 was administered a solution with 22.5% BCAA and group 2 with 45% BCAA. The following parameters were evaluated: anthropometrics, creatinine/height index, urinary 3-methylhistidine, nitrogen balance, stress index, albumin, prealbumin, transferrin, retinol binding protein, lymphocytes, delayed cutaneous sensitivity tests, studies of hepatic function, and plasma aminogram. In group 2 a more positive nitrogen balance, a greater drop in the stress index, a rise in plasma prealbumin and retinol binding protein levels, an increase in the creatinine/height index, and a more marked fall in the urinary excretion of 3-methylhistidine were found. When solutions with a high BCAA content were administered, there was an increase in the plasma concentrations of these amino acids in the BCAA/aromatic amino acid quotient and a decrease in the aromatic amino acids. Plasma concentrations of leucine and valine achieved very high, potentially toxic, levels at 15 days when solutions with high BCAA content were used. It is concluded that solutions with BCAA are advisable for use in the septic patient in the increased protein catabolic phase, where positive nitrogen balance, a reduction in muscle protein catabolism, and faster recovery of muscle and visceral protein were obtained.

Mechanisms of protein conservation during xylitol infusion after burn injury in rats: isotope kinetics and indirect calorimetry

In order to study the mechanisms by which nutrients influence post-trauma metabolism, Sprague-Dawley rats received a 25% full-thickness burn and were randomly assigned to receive 12.5 g kg-1 bodyweight (BW) per day amino acids (AA) only, AA and 14.7 g hydrous glucose kg-1 BW per day or AA and 14.7 g hydrous xylitol kg-1 BW per day. After 4 days of hypocaloric feeding, rats receiving xylitol had a cumulative nitrogen balance of +213 +/- 82 mg N, which was significantly (P less than 0.001) better compared with either the AA with only -493 +/- 61 mg N or the AA and glucose group (P less than 0.01) with -160 +/- 101 mg N. During glucose infusion reduction of insulin-mediated fat oxidation was partially compensated by an increase in glucose oxidation. Xylitol infusions resulted in increased glucose oxidation compared with the amino acid only group without simultaneously reduced fat oxidation. Although glucose and xylitol are calorically similar, their protein sparing properties and metabolic action after injury cannot be based entirely upon their caloric equivalent.

Metabolic and clinical consequences of changing from high-glucose to high-fat regimens in parenterally fed newborn infants

To evaluate the metabolic and clinical consequences of changing from high-glucose to high-fat regimens during initiation of parenteral nutrition, we performed 22 studies in 11 newborn infants (birth weight (mean +/- SD) 2.54 +/- 0.54 kg, gestational age 37 +/- 3 weeks, postnatal age 8 +/- 3 days) maintained in a constant thermal environment. In a paired design, two isoproteinic (2.4 +/- 0.2 gm/kg/day) and isocaloric (64 +/- 6 kcal/kg/day) regimens differing by source of energy (high glucose vs high lipid) were infused on consecutive days. Environmental and body temperatures were recorded during a 4-hour period, and 24-hour urinary excretions of catecholamines, nitrogen, and C peptide were measured. Despite constant incubator and average skin temperatures, the rectal and interscapular temperatures rose significantly when the high-glucose regimen was changed to a high-lipid regimen. The specific locations of these changes in body temperature suggested brown fat activation. A significant drop in nitrogen retention (63 +/- 9% vs 56 +/- 10%) during the lipid infusion could be further evidence of a metabolic adaptation to the rapid change in energy substrates.

Advances in hospital nutrition

The General Clinical Research Center facilities have been largely responsible for expansion of knowledge in the field of hospital nutrition. Expansion of this knowledge base has led to major medical advances in this century. Without the meticulous attention necessary for metabolic balance studies many if not most of these advances would have been seriously delayed. The role that General Clinical Research Centers have played and will continue to play cannot be overestimated.

The effect of intravenous nutrition on muscle mass and exercise capacity in perioperative patients

This study was undertaken to compare the efficacy of four different types of perioperative intravenous nutritional support. Fifty-five patients undergoing routine major surgery were studied. They were prospectively assigned to one of four study groups. Group 1 received formal total parenteral nutrition (90 g amino acids, 3,000 calories as glucose, per day); Group 2, 100 g glucose per day; Group 3, 90 g amino acids per day; and Group 4, peripheral parenteral nutrition (90 g amino acids plus 1,600 calories, 60 percent as fat per day). Group 1 was maintained on therapy for 3 weeks and the other groups for 8 days. Nitrogen balance, maintenance of body cell mass, serum albumin levels, and maintenance of exercise capacity were measured. Patients receiving peripheral parenteral nutrition maintained their nutritional parameters, as did those receiving total parenteral nutrition. These infusions were both markedly superior to those receiving glucose alone or those receiving amino acids alone. Nitrogen balance was not correlated with maintenance of function, but maintenance of body cell mass was correlated with maintenance of exercise capacity (r = 0.66, p less than or equal to 0.01). We conclude that perioperative peripheral parenteral nutrition, in contradistinction to hypocaloric infusions of glucose or amino acids, is capable of maintaining postoperative muscle mass and function close to preoperative levels after major surgery, and in situations of relatively mild surgical stress, approaches the efficacy of total parenteral nutrition in this regard. A significant correlation exists between changes in body cell mass determined from isotope dilution and changes in the exercise capacity of large muscle masses.

Differences in the serum amino acid pattern of injured and infected children promoted by two parenteral nutrition solutions

The effects of two parenteral nutrition (PN) amino acid solutions (FreAmine II and F080) on the serum amino acid levels of 51 children, 27 affected by multiple trauma and 24 by bacterial sepsis, and aged from 1 month to 12 years, were studied. Serum amino acids were determined on day 1 immediately before administrating PN, and on day 5 during PN. Trauma patients on F080 exhibited higher levels of alanine, aspartate, asparagine, leucine, isoleucine, valine, total branched-chain amino acids (BCAA) and total essential amino acids than those on FreAmine II; in contrast septic children showed similar levels of serum amino acids on both PN solutions. BCAA were lower in septics than in trauma patients, probably as a consequence of an increased utilization of these amino acids in sepsis because of the higher organ protein synthesis typical of this situation. The phenylalanine/tyrosine ratio was found elevated both in septic and trauma children, but it decreased after PN in the latter when using an enriched BCAA solution. Utilization of this solution, partly corrects the metabolic disturbances induced by stress, but the metabolical responses induced either by sepsis or trauma are partially different which may have important implications for patient care.

Low and very low calorie diets

Low and very low calorie diets may be useful for the initial treatment of obesity, but long-term weight loss requires life-style changes in eating and activity patterns. Very low calorie diets cause rapid weight loss and improvement of complications of obesity, but the possibility of severe complications mandates careful selection and close supervision by a health professional team.

Effects of aerobic exercise on energy expenditure and nitrogen balance during very low calorie dieting

Aerobic exercise in addition to severe caloric restriction was studied for its effects on resting energy expenditure (REE), weight loss, and lean tissue preservation in adult women. A formula diet providing 1.5 g protein and 0.5 g carbohydrate (CHO) per kilogram of ideal body weight daily (mean intake 720 kcal/d) was given to 12 overweight inpatients for 4 to 5 weeks. Six subjects remained sedentary (group 1), while the other six subjects (group 2) performed supervised endurance exercise (a total of 27 hours at 50% of maximal oxygen uptake (VO2max) over 4 weeks). Lean tissue preservation was excellent in both groups and was unaffected by the group 2 exercise regimen. Weight loss over 4 weeks in the two groups did not differ (group 1, 6.9 +/- 0.7 kg; group 2, 6.5 +/- 0.7 kg). The VO2max was not increased after 4 weeks of exercise compared with controls. The resting oxygen consumption (rVO2) of both groups declined 10% (P less than .001) in the first seven days of dieting. Thereafter the rVO2 in group 1 remained stable, but a further 17% reduction occurred in group 2 (P less than .03) by the third week of exercise. The free triiodothyronine (fT3) concentration also fell more in group 2 (P less than .05), suggesting a relationship between fT3 and energy expenditure during severe caloric restriction. The ergometer exercise for up to two hours daily was well tolerated. The absence of either a training effect or accelerated weight loss in group 2 may be due to the limited duration (4 weeks) or intensity of the exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Parenteral nutrition via peripheral veins: a feasibility study

Twenty patients who had undergone uncomplicated surgery of moderate severity were randomly allocated to two groups (both n = 10) who were fed using a peripheral vein for up to six days. Group I received, each day, a nutrient solution providing 10 grams of nitrogen as Perifusin (E Merck Ltd) and 1400 calories as dextrose and Intralipid (Kabivitrum Ltd) with an osmolality of 490 mosmol/kg. Group II received only 15 grams of nitrogen per day as Perifusin with an osmolality of 376 mosmol/kg. The mean (+/- s.e. mean) nitrogen balance over the study was similar in both groups, in Group I being -1.23 +/- 0.89, and in Group II being -1.05 +/- 1.08 g (P greater than 0.05 Mann-Whitney U test). The nutrient mixture given to Group I resulted in elevated levels of serum 3-hydroxybutyrate and lower levels of serum non-esterified fatty acids. These data suggest that lipolysis and ketogenesis were suppressed. There was no significant difference in serum lactate levels in either group. Venous thrombophlebitis at the infusion site was assessed daily using Maddox's criteria, with a minimal degree of inflammation occurring in either group. This preliminary study suggests that a total parenteral feeding regimen may be designed for peripheral vein infusion. Further studies are indicated.

Lipolytic response to glucose infusion in human subjects

We have determined the effect of various rates of glucose infusion on the rates of release of glycerol (Ra glycerol), free fatty acids (Ra FFA), and on energy metabolism in normal human volunteers. Plasma kinetics were determined with use of the stable isotopic tracers D-5-glycerol and [1-13C]palmitate, and energy metabolism was determined by indirect calorimetry. The effect of glucose infusion on Ra glycerol and Ra FFA was dose-dependent. At an infusion rate of 1 mg X kg-1 X min-1, no effect on either kinetic factor was noted. At 4 mg X kg-1 X min-1, both Ra glycerol and Ra FFA were suppressed; at 8 mg X kg-1 X min-1, Ra FFA was even more depressed, but Ra glycerol was similar to the value during the 4 mg X kg-1 X min-1 infusion. At all infusion rates tested, the amount of potential energy available from the sum of the glucose infusion and endogenously mobilized fat was always greater than when no glucose was infused. Glucose decreased fat mobilization by both inhibiting lipolysis and stimulating reesterification, thus causing a significant increase in triglyceride-fatty acid substrate cycling within the adipose tissue.

Potential life-threatening cardiac arrhythmias associated with a conventional hypocaloric diet

Nine obese children (mean age 12.7 years, mean overweight 74.2%) were treated for 3 weeks with a very low calorie diet containing high quality protein. Eight patients (patients A) received a commercially available diet (240 kcal/1004 kJ/day) and 1 patient (patient B) a homemade dietary regimen (500 kcal/2100 kJ/day). Both preparations were supplemented with micronutrients; however, the daily intake of minerals was significantly less in patient B. All patients were monitored for the appearance of cardiac arrhythmias by frequent 24-hour Holter recordings. In patients A the mean loss of body weight was 9.4 +/- 2.4 kg, patient B lost 8.7 kg. The mean daily nitrogen balance was negative (patients A: 10.2 g/day, patient B: 6.8 g/day). Frequent blood chemistry evaluations were unremarkable. On the 14th day of treatment patient B developed arrhythmias (ventricular couplets, non-sustained ventricular tachycardias); in patients A no ventricular dysrhythmias were observed. Our data suggest that very low calorie diets containing protein of high biologic value can be associated with potentially dangerous arrhythmias.

Estimation of nitrogen balance based on a six-hour urine collection in infants

The accuracy of a 6-hr vs a 24-hr urine collection for the determination of urinary urea nitrogen was studied in 15 infants. Patient's age ranged from 2 weeks to 3 yr, encompassing a wide variety of diagnoses. All patients had normal renal function at the time of the study. Participants had indwelling foley catheters throughout the study. Urine specimens were collected over a continuous 24-hr period. Aliquots obtained from urine collected over 0 to 6 hr and the total urine collection were analyzed utilizing the urease enzymatic method in the Astra. Statistical analysis was performed comparing the actual 24-hr determination to the estimation based on the 6-hr collection, utilizing linear regression. The analysis of data produced a highly significant correlation (r = 0.904, p less than 0.0001). When a 24-hr urine collection is not possible, a 6-hr collection is a useful alternative for the calculation of nitrogen balance in infants.

Supplement feeds and nitrogen and calorie balance following femoral neck fracture

A 10 day study of nitrogen and calorie balance has been undertaken in 61 women patients aged 65-96 years (mean age 81 years) with femoral neck fractures. All underwent fracture surgery with an inhalation anaesthetic lasting from 45 min to 2 h. Intake of ward food varied widely but was always low with a mean of 127 mg N kg-1 and 17 kcal kg-1 daily. Daily nitrogen production was 85-250 mg N kg-1 (mean 158 mg N kg-1) and calorie expenditure was 17-48 kcal kg-1 (mean 32 kcal kg-1). These were greatest in trochanteric fracture patients. Of the 61 patients, 90 per cent were in negative nitrogen balance with a mean 8 day deficit of 411 mg N kg-1 and all in negative calorie balance, mean 141 kcal kg-1. The deficits were greatest in trochanteric fracture patients. Sip feeding with supplementary enriched drinks raised protein and calorie intake substantially. Both nitrogen and calorie balance were significantly improved, but large calorie deficits remained; intolerance of the supplements proved to be a handicap in correcting the deficits in many patients.

Ambient temperature and ketone body plasma concentration in fasting geese

The effect on ketonemia of alternate exposure to ambient temperatures (Ta) of 25 and 5 degrees C was investigated in fasting geese. Three experimental birds were compared to three controls continuously exposed to 25 degrees C Ta while fasting. During the first 9 days of fasting, when both groups were exposed to 25 degrees C, plasma concentration of beta-hydroxybutyrate (beta-OHB) increased similarly in both, from 0.10 +/- 0.02 to 6.62 +/- 0.71 mmol X L-1. It later plateaued at 8-9 mmol X L-1 in the control birds. When the experimental birds were exposed to 5 degrees C Ta between the 9th and 15th day of the fast, it increased further during the first 24 h but thereafter decreased of 57%, from 8.62 +/- 1.56 to 3.73 +/- 1.24 mmol X L-1. This decrease was reversed within the 6 days of return to 25 degrees C Ta. In both groups, plasma acetoacetate (AcAc) concentration remained very low during the fast: 51 +/- 1 mumol X L-1. This reversible cold-induced effect on ketonemia may be used for investigating the possible role of ketone bodies in protein sparing during fasting.

Lack of modulation of postoperative immunosuppression by isotonic amino acid infusion

Effects of an isotonic amino acid solution on the immune defence systems of surgical patients were studied. Twenty-two patients admitted for major abdominal operations were randomly allocated into two groups. Eleven of them received 1 liter of 3% amino acid solution daily for 5 days postoperatively, while 11 control patients received balanced 5% glucose-containing electrolyte solutions. Immune variables were studied preoperatively and at 1, 3 to 4, and 6 to 7 days postoperatively. These studies included leukocyte and differential counts, T (OKT3+), B (sIg+), T helper/inducer (OKT4+) and suppressor/cytotoxic (OKT8+) cell determinations, measurement of in vitro lymphocytic responses to phytohemagglutinin (PHA), pokeweed mitogen (PWM) and Staphylococcus aureus Cowan I (StaCw) in cultures of separated lymphocytes, and to PHA, concanavalin A (Con A), and PWM in whole blood cultures. B lymphocyte functions were studied by measuring synthesis of immunoglobulins IgG, IgM, and IgA in the cell culture medium when lymphocytes were stimulated with PWM alone and in the presence of Con A or hydrocortisone. Postoperative amino acid infusion slightly improved the capacity of lymphocytes to synthetize and secrete IgG and IgM. By contrast, no improvement was seen in cell counts or lymphocyte transformation patterns.

Parenteral nourishment of patients undergoing surgical or traumatic stress

Severe surgical or other traumatic stress initiates an integrated central nervous system and metabolic response characterized by catabolism which selectively preserves vital organs, drawing on peripheral tissue proteins for required amino acids. When oral intake is prohibited adequate intravenous nutritional support hastens convalescence and may be life-saving. Intravenous nutrients routinely consist of amino acids for replacement of lost protein, a nonprotein calorie source--usually glucose, and vitamins and minerals. Lipid, infrequently used in routine surgery as part of the calorie source, supplies essential fatty acids and prevents side effects resulting with large amounts of intravenous glucose. Lipid has other benefits. Stress-induced hormones stimulate lipid catabolism. When lipid is used for part of the calorie requirement in intravenous feedings, the plasma insulin level is reduced and peripheral amino acids become available for synthesis of critically needed visceral proteins. Recent work has shown that the branched chain amino acids carnitine and some species of lipid added to intravenous nutrient formulations postoperatively affect the nitrogen retention and may hasten convalescence. Further work should be directed at understanding the unique biochemical changes occurring after injury, devising objective assay procedures to measure the severity of the response and improving intravenous formulations for the acutely ill surgical patient.

Is it possible to evaluate the efficacy of amino acid solutions after major surgical procedures or accidental injuries? Evaluation in a randomized and prospective study

Two unbalanced amino acid solutions (essential amino acids, branched-chain amino acids) were compared to a complete and balanced amino acid solution with regard to efficacy of nitrogen balance. Patients were randomized to receive the amino acid solutions over 3 days for each regimen. The patients were examined postoperatively or directly after accidental trauma. Nonprotein calories were given as 40 kcal/kg/day consisting of 50% fat and 50% glucose. Nitrogen was given at the amount of 0.15 g N/kg/day. Unbalanced amino acid solutions gave a 2-fold more negative nitrogen balance than a balanced and complete amino acid solution. However, this difference disappeared and nitrogen balance approached equilibrium irrespective of the amino acid composition of the infused solutions when nitrogen in blood products was accounted for. All patients received a considerable amount of blood products in a comparable but unpredictable way. Blood products corresponded to around 40% of the daily nitrogen intake. Our study demonstrates that it is not possible to test the efficacy of amino acids for nitrogen retention in patients who are in the need of blood-product transfusions. It is likely that amino acids in blood proteins serve as a significant amino acid source that is utilized for resynthesis of body proteins especially in flow-phase patients with high protein breakdown. This fact has not been sufficiently accounted for in the previous literature.

Multidisciplinary treatment of obesity with a protein-sparing modified fast: results in 668 outpatients

Six hundred sixty-eight obese outpatients, 71 per cent (+/- 34) in excess of ideal weight, were enrolled in a multidisciplinary weight control program. The major components of the program included nutrition, education, behavior modification, and exercise. Rapid weight loss was accomplished using a very low calorie (less than 800 kcal) ketogenic diet. Patients adhered to the protein sparing modified fast (PSMF) for 17 +/- 12 weeks and averaged 9 +/- 17 weeks in a refeeding/maintenance program. Mean weight loss was 47 +/- 29 lb (21 +/- 13 kg) at the point of minimum weight and 41 +/- 29 lb (19 +/- 13 kg) at the end of the maintenance period. Systolic and diastolic blood pressure and serum triglycerides fell significantly in men and women. Success in weight loss was greatest in the heaviest patients, those who adhered the longest to the PSMF, and those who stayed the longest in the maintenance program.

Relative value of glucose and amino acids in preserving exercise capacity in the postoperative period

The value of crystalline amino acids compared with glucose in maintaining functional muscle mass (maximum exercise capacity) in the perioperative period was studied. Twelve surgical patients received 100 g of glucose (Group 1) for 7 to 10 days perioperatively, and 12 (Group 2) received 90 g of crystalline amino acids for a similar period. Maximum exercise capacity, nitrogen balance, and serum albumin were studied. The use of amino acids instead of glucose spared nitrogen. Net nitrogen loss was 64.7 +/- 6.7 g in Group 1 compared with 34.7 +/- 4 g in Group 2 (p less than or equal to 0.001). Exercise capacity decreased 13.8 +/- 4.5 percent in Group 1 and 13.3 +/- 2.9 percent in group 2. The serum albumin level decreased by 0.30 +/- 0.2 g/100 ml in Group 1 compared with 0.34 +/- 0.15 g/100 ml in Group 2. These differences were not significant. Changes in serum albumin were correlated with changes in exercise capacity (r = 0.7, p less than or equal to 0.002), but neither was significantly correlated with nitrogen loss. We concluded that the use of amino acids instead of glucose during moderate periods of semi-starvation associated with moderate trauma will not influence loss of exercise capacity significantly, although some nitrogen will be spared; patients undergoing moderately severe surgical procedures accompanied by moderate periods of semistarvation will lose approximately 14 percent of their exercise capacity; and loss of exercise capacity is not correlated with loss of nitrogen under these conditions but is loosely correlated with changes in serum albumin levels.

The effect of major thermal injury on plasma ketone body levels

Eleven patients with more than 30% total body surface burns were studied during 3 days of starvation and three more days of unrestricted feeding following their injury. All patients developed marked protein mobilization as demonstrated by 3rd day urine nitrogen excretion of 17.1 g daily compared to control excretion of 11.8 g N daily. As a group, the patients failed to mount the expected ketonemic response during their initial period of starvation. Whereas normal fasted controls achieved plasma ketone body levels of 727 +/- 81 mumol/liter, the burn patients responded with an average level of 385 +/- 77 mumol/liter (p less than 0.01).

Lipids, lipoproteins and fatty acid composition in obese adolescents undergoing a very low calorie diet

Sixteen obese adolescents (mean +/- SD age: group I 12.5 +/- 2.1 and group II 12.0 +/- 2.5 years) were treated at least 3 weeks with two different very low calorie diet (VLCD) regimens. The VLCD in group I contained 33g proteins, 25.5g carbohydrates and 0.7g fat (240 kcal, 1004KJ) and in group II 44g protein, 33g carbohydrates and 0.9g fat (320 kcal, 1339KJ). After the 3 weeks treatment total serum cholesterol decreased from 180 +/- 34 mg/dl in group I and 184 +/- 34 mg/dl in group II respectively, to 125 + 16 mg/dl and 120 + 22 mg/dl. This fall was mainly due to the highly significant decrease of LDL-cholesterol. VLDL-cholesterol, HDL-cholesterol and triglycerides in group I remained almost unchanged. In group II triglycerides increased significantly from 81 +/- 19 mg/dl to 104 +/- 19 mg/dl and HDL-cholesterol decreased slightly. The LDL-C HDL-C- ratio in both groups improved considerably. Fatty acid composition of the serum lipids changed only slightly: In total serum linoleic acid levels declined slightly in group I and remained constant in group II. Linoleic acid content in cholesterylesters declined moderately in group I from 37.5 +/- 5.6% to 34.8 +/- 5.6% whereas arachidonic acid increased slightly in both groups. In phospholipids, oleic acid declined in both groups significantly, linoleic acid declined significantly in group I and arachidonic acid increased in group I significantly. Similar changes occurred in triglycerides. After 3 weeks treatment with a practically fat free alimentation no biochemical signs of essential fatty acid deficiency could be detected.