Effect of orthotopic liver transplantation (OLT) on branched-chain amino acid requirement

Determining amino acid requirements in humans

Amino acids form the building blocks of body protein. Dietary protein sources provide the amino acids needed, but protein sources vary widely in amio acid composition. To ensure humans can meet body demands for amino acids, amino acid intake recommendations are provided by the Dietary Reference Intakes (DRI) and by Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU). Current amino acid intake recommendations, however, are based on data collected predominantly from young adult males. The development of the minimally invasive indicator amino acid oxidation (IAAO) method has permitted the evaluation of amino acid requirements in various vulnerable populations. The purpose of this review is to discuss recent amino acid requirement studies in school-age children, pregnant females and the elderly determined using the IAAO technique. These requirements will help to inform evidence-based recommendations that will help to guide dietary guidelines.

Nutritional Strategies to Manage Malnutrition and Sarcopenia following Liver Transplantation: A Narrative Review

Persisting or newly developed malnutrition and sarcopenia after liver transplant (LT) are correlated with adverse health outcomes. This narrative review aims to examine the literature regarding nutrition strategies to manage malnutrition and sarcopenia after LT. The secondary aims are to provide an overview of the effect of nutrition strategies on the incidence of infections, hospital length of stay (LOS), acute cellular rejection (ACR), and mortality after LT. Four databases were searched. A total of 25 studies, mostly of mid-high quality, were included. Six studies found a beneficial effect on nutritional parameters using branched-chain amino acids (BCAA), immunomodulating diet (IMD), or enteral nutrition (EN) whereas two studies using beta-hydroxy-beta-methylbutyrate (HMB) found a beneficial effect on muscle mass and function. Fourteen studies using pre- or pro-biotics, IMD, and EN were effective in lowering infection and six studies using IMD, BCAA or HMB reported reduced hospital LOS. Finally, four studies using HMB and vitamin D were effective in reducing ACR and one study reported reduced mortality using vitamin D after LT. In conclusion, nutritional intervention after LT has different beneficial effects on malnutrition, sarcopenia, and other advert outcomes. Additional large and well-constructed RCTs using validated tools to assess nutritional status and sarcopenia are warranted to ensure more robust conclusions.

Deficits in Muscle Strength and Physical Performance Influence Physical Activity in Sarcopenic Children After Liver Transplantation

Sarcopenia is a muscle disease characterized by reduced skeletal muscle mass (SMM), muscle strength, and physical performance. Reduced SMM has been identified in children after liver transplantation (LT), but no information related to muscle strength/physical performance or lifestyle factors contributing to sarcopenia is available. We hypothesized that sarcopenia, as determined by measures of SMM, muscle strength, and physical performance, is highly prevalent in children after LT and is related to poor diet quality (DQ) and physical inactivity. A cross-sectional study in post-LT children (n = 22) and age-matched healthy controls (n = 47) between the ages of 6 and 18 years examining body composition (dual energy X-ray absorptiometry and multiple skinfold), measures of muscle strength (handgrip, sit-to-stand, and push-ups), physical performance (6-minute walk test and stair climb test), diet (3-day food intake), and physical activity (accelerometer) was conducted. Low muscle strength/physical performance and SMM (SMM z scores ≤-1.5) were defined by values 2 standard deviations below the mean values for age- and sex-matched controls. Sarcopenia occurred in 36% of children who underwent LT, and they had significantly lower scores for muscle strength (sit-to-stand and push-up tests) and physical performance (stair climb test) than controls (P < 0.05). Deficits in physical performance in children with sarcopenia were predominantly revealed by longer stair climbing times (P = 0.03), with no differences in other muscle tests. Low SMM, muscle strength, and physical performance were associated with a lower amount of time spent in fairly and very active physical activity, but no associations with DQ were found. Sarcopenia is highly prevalent in children after LT and is related to lower moderate-to-vigorous physical activity. Development of effective rehabilitation strategies to treat sarcopenia are needed in post-LT children.

Effects of ω-3 fish oil lipid emulsion combined with parenteral nutrition on patients undergoing liver transplantation

BACKGROUND

The effect of parenteral nutrition (PN) support supplemented with ω-3 fatty acids was investigated in a randomized, controlled clinical trial at the Affiliated Drum Tower Hospital, Medical School of Nanjing University.

MATERIALS AND METHODS

Ninety-eight patients with the diagnosis of end-stage liver disease or hepatic cellular carcinoma were admitted for orthotopic liver transplantation at the Affiliated Drum Tower Hospital. The patients were randomly divided into 3 groups: diet group (n = 32), PN group (n = 33), and polyunsaturated fatty acid (PUFA) group (n = 33). Patients in the PN and PUFA groups received isocaloric and isonitrogenous PN for 7 days after surgery. Venous heparin blood samples were obtained for assay on days 2 and 9 after surgery. A pathological test was performed after reperfusion of the donor liver and on day 9.

RESULTS

Alanine aminotransferase levels were improved significantly by PUFA treatment compared with traditional PN support (P < .05). Compared with the results on day 9 in the PN group, a significant difference was seen in the extent of increase of the prognostic nutrition index and prealbumin in the PUFA group. The pathological results also showed that ω-3 fatty acid supplementation reduced hepatic cell injury. PUFA therapy also decreased the incidence of infectious morbidities and shortened the posttransplant hospital stay significantly.

CONCLUSION

Posttransplant PN support can greatly improve metabolism of protein and nutrition states of patients. ω-3 fatty acid-supplemented PN significantly reduces injury of the transplanted liver, decreases the incidence of infectious morbidities, and shortens posttransplant hospital stay.

Liver-protecting effects of omega-3 fish oil lipid emulsion in liver transplantation

AIM

To investigate the liver-protecting effect of parenteral nutrition (PN) support with omega-3 fatty acids in a randomized controlled clinical trial.

METHODS

Sixty-six patients with the diagnosis of end-stage liver disease or hepatic cellular carcinoma were admitted to the Affiliated Drum Tower Hospital, Nanjing University, China for orthotopic liver transplantation. The patients were randomly divided into two groups: PN group (n = 33) and polyunsaturated fatty acid (PUFA) group (n = 33). All patients received isocaloric and isonitrogenous PN for seven days after surgery, and in PUFA group omega-3 fish oil lipid emulsion replaced part of the standard lipid emulsion. Liver function was tested on days 2 and 9 after surgery. Pathological examination was performed after reperfusion of the donor liver and on day 9. Clinical outcome was assessed based on the post-transplant investigations, including: (1) post-transplant mechanical ventilation; (2) total hospital stay; (3) infectious morbidities; (4) acute and chronic rejection; and (5) mortality (intensive care unit mortality, hospital mortality, 28-d mortality, and survival at a one-year post-transplant surveillance period).

RESULTS

On days 2 and 9 after operation, a significant decrease of alanine aminotransferase (299.16 U/L ± 189.17 U/L vs 246.16 U/L ± 175.21 U/L, P = 0.024) and prothrombin time (5.64 s ± 2.06 s vs 2.54 s ± 1.15 s, P = 0.035) was seen in PUFA group compared with PN group. The pathological results showed that omega-3 fatty acid supplement improved the injury of hepatic cells. Compared with PN group, there was a significant decrease of post-transplant hospital stay in PUFA group (18.7 d ± 4.0 d vs 20.6 d ± 4.6 d, P = 0.041). Complications of infection occurred in 6 cases of PN group (2 cases of pneumonia, 3 cases of intra-abdominal abscess and 1 case of urinary tract infection), and in 3 cases of PUFA group (2 cases of pneumonia and 1 case of intra-abdominal abscess). No acute or chronic rejection and hospital mortality were found in both groups. The one-year mortality in PN group was 9.1% (3/33), one died of pulmonary infection, one died of severe intra-hepatic cholangitis and hepatic dysfunction and the other died of hepatic cell carcinoma recurrence. Only one patient in PUFA group (1/33, 3.1%) died of biliary complication and hepatic dysfunction during follow-up.

CONCLUSION

Post-transplant parenteral nutritional support combined with omega-3 fatty acids can significantly improve the liver injury, reduce the infectious morbidities, and shorten the post-transplant hospital stay.

Nutritional interventions for liver-transplanted patients

BACKGROUND

Malnutrition is a common problem for patients waiting for orthotopic liver transplantation and a risk factor for post-transplant morbidity. The decision to initiate enteral or parenteral nutrition, to which patients and at which time, is still debated. The effects of nutritional supplements given before or after liver transplantation, or both, still remains unclear.

OBJECTIVES

The aim of this review was to assess the beneficial and harmful effects of enteral and parenteral nutrition as well as oral nutritional supplements administered to patients before and after liver transplantation.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register (March 2012), the Cochrane Central Register of Controlled Trials (Issue 2 of 12, 2012) in The Cochrane Library, MEDLINE (January 1946 to March 2012), EMBASE (January 1974 to March 2012), Science Citation Index Expanded (January 1900 to March 2012), Social Science Citation Index (January 1961 to October 2010), and reference lists of articles. Manufacturers and experts in the field have also been contacted and relevant journals and conference proceedings were handsearched (from 1997 to October 2010).

SELECTION CRITERIA

Randomised clinical trials of parallel or cross-over design evaluating the beneficial or harmful effects of enteral or parenteral nutrition or oral nutritional supplements for patients before and after liver transplantation were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias of the trials and extracted data. Dichotomous data were reported as odds ratios (OR) and continuous data as mean differences (MD) along with their corresponding 95% confidence intervals (CI). Meta-analysis was not possible due to clinical heterogeneity of included interventions.

MAIN RESULTS

Thirteen trials met the inclusion criteria. Four publications did not report outcomes pre-defined in the review protocol, or other clinically relevant outcomes and additional data could not be obtained. Nine trials could provide data for the review. Most of the 13 included trials were small and at high risk of bias. Meta-analyses were not possible due to clinical heterogeneity of the interventions.No interventions that were likely to be beneficial were identified.For interventions of unknown effectiveness,postoperative enteral nutrition compared with postoperative parenteral nutrition seemed to have no beneficial or harmful effects on clinical outcomes. Parenteral nutrition containing protein, fat, carbohydrates, and branched-chain amino acids with or without alanyl-glutamine seemed to have no beneficial effect on the outcomes of one and three years survival when compared with a solution of 5% dextrose and normal saline. Enteral immunonutrition with Supportan® seemed to have no effect on occurrence of immunological rejection when compared with enteral nutrition with Fresubin®.There is weak evidence that, compared with standard dietary advice, adding a nutritional supplement to usual diet for patients during the waiting time for liver transplantation had an effect on clinical outcomes after liver transplantation. The combination of enteral nutrition plus parenteral nutrition plus glutamine-dipeptide seemed to be beneficial in reducing length of hospital stay after liver transplantation compared with standard parenteral nutrition (mean difference (MD) -12.20 days; 95% CI -20.20 to -4.00). There is weak evidence that the use of parenteral nutrition plus branched-chain amino acids had an effect on clinical outcomes compared with standard parenteral nutrition, but each was beneficial in reducing length of stay in intensive care unit compared to a standard glucose solution (MD -2.40; 95% CI -4.29 to -0.51 and MD -2.20 days; 95% CI -3.79 to -0.61). There is weak evidence that adding omega-3 fish oil to parenteral nutrition reduced the length of hospital stay after liver transplantation (mean difference -7.1 days; 95% CI -13.02 to -1.18) and the length of stay in intensive care unit after liver transplantation (MD -1.9 days; 95% CI -1.9 to -0.22).For interventions unlikely to be beneficial, there is a significant increased risk in acute rejections in malnourished patients with a history of encephalopathy and treated with the nutritional supplement Ensure® compared with usual diet only (MD 0.70 events per patient; 95% CI 0.08 to 1.32).

AUTHORS' CONCLUSIONS

We were unable to identify nutritional interventions for liver transplanted patients that seemed to offer convincing benefits. Further randomised clinical trials with low risk of bias and powerful sample sizes are needed.

Recent advances in determining protein and amino acid requirements in humans

During the past 25 years a significant amount of research has been conducted to determine amino acid requirements in humans. This is primarily due to advancements in the application of stable isotopes to examine amino acid requirements. The indicator amino acid oxidation (IAAO) method has emerged as a robust and minimally invasive technique to identify requirements. The IAAO method is based on the concept that when one indispensable dietary amino acid (IDAA) is deficient for protein synthesis, then the excess of all other IDAA, including the indicator amino acid, will be oxidized. With increasing intakes of the limiting amino acid, IAAO will decrease, reflecting increasing incorporation into protein. Once the requirement for the limiting amino acid is met there will be no further change in the indicator oxidation. The IAAO method has been systematically applied to determine most IDAA requirements in adults. The estimates are comparable to the values obtained using the more elaborate 24h-indicator amino acid oxidation and balance (24h-IAAO/IAAB) model. Due to its non-invasive nature the IAAO method has also been used to determine requirements for amino acids in neonates, children and in disease. The IAAO model has recently been applied to determine total protein requirements in humans. The IAAO method is rapid, reliable and has been used to determine amino acid requirements in different species, across the life cycle and in disease. The recent application of IAAO to determine protein requirements in humans is novel and has significant implications for dietary protein intake recommendations globally.

Nutritional support for liver disease

BACKGROUND

Weight loss and muscle wasting are commonly found in patients with end-stage liver disease. Since there is an association between malnutrition and poor clinical outcome, such patients (or those at risk of becoming malnourished) are often given parenteral nutrition, enteral nutrition, or oral nutritional supplements. These interventions have costs and adverse effects, so it is important to prove that their use results in improved morbidity or mortality, or both.

OBJECTIVES

To assess the beneficial and harmful effects of parenteral nutrition, enteral nutrition, and oral nutritional supplements on the mortality and morbidity of patients with underlying liver disease.

SEARCH METHODS

The following computerised databases were searched: the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, and Science Citation Index Expanded (January 2012). In addition, reference lists of identified trials and review articles and Clinicaltrials.gov were searched. Trials identified in a previous systematic handsearch of Index Medicus were also considered. Handsearches of a number of medical journals, including abstracts from annual meetings, were done. Experts in the field and manufacturers of nutrient formulations were contacted for potential references.

SELECTION CRITERIA

Randomised clinical trials (parallel or cross-over design) comparing groups of patients with any underlying liver disease who received, or did not receive, enteral or parenteral nutrition or oral nutritional supplements were identified without restriction on date, language, or publication status. Six categories of trials were separately considered: medical or surgical patients receiving parenteral nutrition, enteral nutrition, or supplements.

DATA COLLECTION AND ANALYSIS

The following data were sought in each report: date of publication; geographical location; inclusion and exclusion criteria; the type of nutritional support and constitution of the nutrient formulation; duration of treatment; any nutrition provided to the controls; other interventions provided to the patients; number, sex, age of the study participants; hospital or outpatient status; underlying liver disease; risks of bias (sequence generation, allocation concealment, blinding, incomplete outcome reporting, intention-to-treat analysis, selective outcome reporting, others (vested interests, baseline imbalance, early stopping)); mortality; hepatic morbidity (development or resolution of ascites or hepatic encephalopathy, occurrence of gastrointestinal bleeding); quality of life scores; adverse events; infections; lengths of stay in the hospital or intensive care unit; costs; serum bilirubin; postoperative complications (surgical trials only); and nutritional outcomes (nitrogen balance, anthropometric measurements, body weight). The primary outcomes of this review were mortality, hepatic morbidity, quality of life, and adverse events. Data were extracted in duplicate; differences were resolved by consensus.Data for each outcome were combined in a meta-analysis (RevMan 5.1). Estimates were reported using risk ratios or mean differences, along with the 95% confidence intervals (CI). Both fixed-effect and random-effects models were employed; fixed-effect models were reported unless one model, but not the other, found a significant difference (in which case both were reported). Heterogeneity was assessed by the Chi(2) test and I(2) statistic. Subgroup analyses were planned to assess specific liver diseases (alcoholic hepatitis, cirrhosis, hepatocellular carcinoma), acute or chronic liver diseases, and trials employing standard or branched-chain amino acid formulations (for the hepatic encephalopathy outcomes). Sensitivity analyses were planned to compare trials at low and high risk of bias and trials reported as full papers. The following exploratory analyses were undertaken: 1) medical and surgical trials were combined for each nutritional intervention; 2) intention-to-treat analyses in which missing dichotomous data were imputed as best- and worst-case scenarios; 3) all trials were combined to assess mortality; 4) effects were estimated by absolute risk reductions.

MAIN RESULTS

Thirty-seven trials were identified; only one was at low risk of bias. Most of the analyses failed to find any significant differences. The significant findings that were found were the following: 1) icteric medical patients receiving parenteral nutrition had a reduced serum bilirubin (mean difference (MD) -2.86 mg%, 95% CI -3.82 mg% to -1.89 mg%, 3 trials) and better nitrogen balance (MD 3.60 g/day, 95% CI 0.86 g/day to 6.34 g/day, 1 trial); 2) surgical patients receiving parenteral nutrition had a reduced incidence of postoperative ascites only in the fixed-effect model (RR 0.65, 95% CI 0.48 to 0.87, 2 trials, I(2) = 70%) and one trial demonstrated a reduction in postoperative complications, especially infections (pneumonia in particular); 3) enteral nutrition may have improved nitrogen balance in medical patients (although a combination of the three trials was not possible); 4) one surgical trial of enteral nutrition found a reduction in postoperative complications; and 5) oral nutritional supplements had several effects in medical patients (reduced occurrence of ascites (RR 0.57, 95% CI 0.37 to 0.88, 3 trials), possibly (significant differences only seen in the fixed-effect model) reduced rates of infection (RR 0.49, 95% CI 0.24 to 0.99, 3 trials, I(2) = 14%), and improved resolution of hepatic encephalopathy (RR 3.75, 95% CI 1.15 to 12.18, 2 trials, I(2) = 79%). While there was no overall effect of the supplements on mortality in medical patients, the one low risk of bias trial found an increased risk of death in the recipients of the supplements. Three trials of supplements in surgical patients failed to show any significant differences. No new information was derived from the various subgroup or sensitivity analyses. The exploratory analyses were also unrevealing except for a logical conundrum. There was no difference in mortality when all of the trials were combined, but the trials of parenteral nutrition found that those recipients had better survival (RR 0.53, 95% CI 0.29 to 0.98, 10 trials). Either the former observation represents a type II error or the latter one a type I error.

AUTHORS' CONCLUSIONS

The data do not compellingly justify the routine use of parenteral nutrition, enteral nutrition, or oral nutritional supplements in patients with liver disease. The fact that all but one of these trials were at high risks of bias even casts doubt on the few benefits that were demonstrated. Data from well-designed and executed randomised trials that include an untreated control group are needed before any such recommendation can be made. Future trials have to be powered adequately to see small, but clinically important, differences.

Nutritional support for liver disease

BACKGROUND

Weight loss and muscle wasting are commonly found in patients with end-stage liver disease. Since there is an association between malnutrition and poor clinical outcome, such patients (or those at risk of becoming malnourished) are often given parenteral nutrition, enteral nutrition, or oral nutritional supplements. These interventions have costs and adverse effects, so it is important to prove that their use results in improved morbidity or mortality, or both.

OBJECTIVES

To assess the beneficial and harmful effects of parenteral nutrition, enteral nutrition, and oral nutritional supplements on the mortality and morbidity of patients with underlying liver disease.

SEARCH METHODS

The following computerised databases were searched: the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, and Science Citation Index Expanded (January 2012). In addition, reference lists of identified trials and review articles and Clinicaltrials.gov were searched. Trials identified in a previous systematic handsearch of Index Medicus were also considered. Handsearches of a number of medical journals, including abstracts from annual meetings, were done. Experts in the field and manufacturers of nutrient formulations were contacted for potential references.

SELECTION CRITERIA

Randomised clinical trials (parallel or cross-over design) comparing groups of patients with any underlying liver disease who received, or did not receive, enteral or parenteral nutrition or oral nutritional supplements were identified without restriction on date, language, or publication status. Six categories of trials were separately considered: medical or surgical patients receiving parenteral nutrition, enteral nutrition, or supplements.

DATA COLLECTION AND ANALYSIS

The following data were sought in each report: date of publication; geographical location; inclusion and exclusion criteria; the type of nutritional support and constitution of the nutrient formulation; duration of treatment; any nutrition provided to the controls; other interventions provided to the patients; number, sex, age of the study participants; hospital or outpatient status; underlying liver disease; risks of bias (sequence generation, allocation concealment, blinding, incomplete outcome reporting, intention-to-treat analysis, selective outcome reporting, others (vested interests, baseline imbalance, early stopping)); mortality; hepatic morbidity (development or resolution of ascites or hepatic encephalopathy, occurrence of gastrointestinal bleeding); quality of life scores; adverse events; infections; lengths of stay in the hospital or intensive care unit; costs; serum bilirubin; postoperative complications (surgical trials only); and nutritional outcomes (nitrogen balance, anthropometric measurements, body weight). The primary outcomes of this review were mortality, hepatic morbidity, quality of life, and adverse events. Data were extracted in duplicate; differences were resolved by consensus.Data for each outcome were combined in a meta-analysis (RevMan 5.1). Estimates were reported using risk ratios or mean differences, along with the 95% confidence intervals (CI). Both fixed-effect and random-effects models were employed; fixed-effect models were reported unless one model, but not the other, found a significant difference (in which case both were reported). Heterogeneity was assessed by the Chi(2) test and I(2) statistic. Subgroup analyses were planned to assess specific liver diseases (alcoholic hepatitis, cirrhosis, hepatocellular carcinoma), acute or chronic liver diseases, and trials employing standard or branched-chain amino acid formulations (for the hepatic encephalopathy outcomes). Sensitivity analyses were planned to compare trials at low and high risk of bias and trials reported as full papers. The following exploratory analyses were undertaken: 1) medical and surgical trials were combined for each nutritional intervention; 2) intention-to-treat analyses in which missing dichotomous data were imputed as best- and worst-case scenarios; 3) all trials were combined to assess mortality; 4) effects were estimated by absolute risk reductions.

MAIN RESULTS

Thirty-seven trials were identified; only one was at low risk of bias. Most of the analyses failed to find any significant differences. The significant findings that were found were the following: 1) icteric medical patients receiving parenteral nutrition had a reduced serum bilirubin (mean difference (MD) -2.86 mg%, 95% CI -3.82 mg% to -1.89 mg%, 3 trials) and better nitrogen balance (MD 3.60 g/day, 95% CI 0.86 g/day to 6.34 g/day, 1 trial); 2) surgical patients receiving parenteral nutrition had a reduced incidence of postoperative ascites only in the fixed-effect model (RR 0.65, 95% CI 0.48 to 0.87, 2 trials, I(2) = 70%) and one trial demonstrated a reduction in postoperative complications, especially infections (pneumonia in particular); 3) enteral nutrition may have improved nitrogen balance in medical patients (although a combination of the three trials was not possible); 4) one surgical trial of enteral nutrition found a reduction in postoperative complications; and 5) oral nutritional supplements had several effects in medical patients (reduced occurrence of ascites (RR 0.57, 95% CI 0.37 to 0.88, 3 trials), possibly (significant differences only seen in the fixed-effect model) reduced rates of infection (RR 0.49, 95% CI 0.24 to 0.99, 3 trials, I(2) = 14%), and improved resolution of hepatic encephalopathy (RR 3.75, 95% CI 1.15 to 12.18, 2 trials, I(2) = 79%). While there was no overall effect of the supplements on mortality in medical patients, the one low risk of bias trial found an increased risk of death in the recipients of the supplements. Three trials of supplements in surgical patients failed to show any significant differences. No new information was derived from the various subgroup or sensitivity analyses. The exploratory analyses were also unrevealing except for a logical conundrum. There was no difference in mortality when all of the trials were combined, but the trials of parenteral nutrition found that those recipients had better survival (RR 0.53, 95% CI 0.29 to 0.98, 10 trials). Either the former observation represents a type II error or the latter one a type I error.

AUTHORS' CONCLUSIONS

The data do not compellingly justify the routine use of parenteral nutrition, enteral nutrition, or oral nutritional supplements in patients with liver disease. The fact that all but one of these trials were at high risks of bias even casts doubt on the few benefits that were demonstrated. Data from well-designed and executed randomised trials that include an untreated control group are needed before any such recommendation can be made. Future trials have to be powered adequately to see small, but clinically important, differences.

Role of branched-chain amino acids in management of cirrhosis and hepatocellular carcinoma

Altered protein and energy metabolism is a hallmark of chronic liver disease, characterized by decreased plasma branched-chain amino acids (BCAA) and increased plasma aromatic amino acids (AAA). Overwhelming evidence has indicated that the incidence of complications of chronic liver disease increases with malnutrition. Hence nutritional management in patients with chronic liver disease must receive high priority. The use of BCAA supplementation has been a controversial subject. This review summarizes published results of BCAA supplementation as a nutritional therapy for patients with cirrhosis and hepatocellular carcinoma (HCC). On balance, it would be appropriate to conclude that BCAA are associated with decreased frequency of complications of cirrhosis and improved nutritional status when prescribed as a maintenance therapy for patients with cirrhosis. More studies are, however, required to identify those who might benefit most from BCAA supplementation.

Indicator amino acid oxidation: concept and application

The indicator amino acid oxidation (IAAO) method is based on the concept that when 1 indispensable amino acid (IDAA) is deficient for protein synthesis, then all other IDAA, including the indicator amino acid, will be oxidized. With increasing intakes of the limiting amino acid, IAAO will decrease, reflecting increasing incorporation into protein. Once the requirement for the limiting amino acid is met, there will be no further change in the indicator oxidation. Originally, the IAAO method was designed to determine amino acid requirements in growing pigs. The minimally invasive IAAO method developed in humans has been systematically applied to determine IDAA requirements in adults. Due to its noninvasive nature, the IAAO method has also been used to determine requirements for amino acids in neonates and children, and in disease. The IAAO model has recently been applied to determine the metabolic availability (MA) of amino acids from dietary proteins and to determine total protein requirements. The IAAO method is robust, rapid, and reliable; it has been used to determine amino acid requirements in different species, across the life cycle, and in diseased populations. The recent application of IAAO to determine MA of amino acids and protein requirements is also very novel.

Role of branched-chain amino acids in liver disease: the evidence for and against

PURPOSE OF REVIEW

There is ample evidence that patients with liver disease have an ongoing energy and protein catabolism. Nutritional management in these patients must receive high priority. The administration of branched-chain amino acids to patients with liver disease has been a controversial subject. This review is an update on the data available from various studies involving branched-chain amino acids supplementation in patients with chronic liver disease and associated complications.

RECENT FINDINGS

This review summarizes the results of nutritional interventions involving branched-chain amino acids supplementation carried out in different centres around the world. It is interesting to note that no toxic effects of branched-chain amino acids supplementation have been reported in any of these trials.

SUMMARY

Administration of branched-chain amino acids stimulates hepatic protein synthesis in patients with chronic liver disease and this could contribute significantly to improving their nutritional status, and result in a better quality of life. The beneficial role of branched-chain amino acids supplementation in patients with chronic hepatic encephalopathy has been clearly documented in some studies but the exact mechanism of action is still not clear.

Extracellular amino acid levels in the human liver during transplantation: a microdialysis study from donor to recipient

Using microdialysis, we have monitored extracellular levels of amino acids and related amines in the human liver at three stages of the transplantation procedure: donor retrieval, back table preparation and during 48 h post-implantation. By comparing the ratio of mean levels at the donor and back table stages, with the ratio between early (2-6 h) and late (43-48 h) post-reperfusion, these amines were classified into one of three groups. In one group, back table levels were markedly higher than during the donor stage, with levels declining over time post-reperfusion. A second group had much lower levels in the back table than during the donor phase, and post-reperfusion levels were either stable or increased over time. Concentrations of amino acids in the final group remained relatively constant at all stages. This study illustrates the value of microdialysis in providing organ-specific metabolic data that may indicate specific mechanisms of poor graft function.