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PubMed2005

Oral administration of branched-chain amino acids activates the mTOR signal in cirrhotic rat liver.

BCAA granules (a mixture of branched-chain amino acids) have been used to reverse the hypoalbuminemia of decompensated liver cirrhotic patients in Japan. Our previous studies showed that BCAA promoted albumin secretion through the mTOR signal transduction pathway in rat primary hepatocyte culture [Ijichi C, Matsumura T, Tsuji T, Eto Y. Branched-chain amino acids promote albumin synthesis in rat primary hepatocytes through the mTOR signal transduction system. Biochem Biophys Res Commun 2003;303:59-64]. However, the mTOR-activating effect of BCAA in the experimental cirrhotic animals presenting with hypoalbuminemia has not yet been examined. The purpose of this study is to assess whether oral administration of BCAA induces mTOR activity in the livers of normal rats and CCl(4)-induced cirrhotic rats (CCl(4) rats). Biochemical analysis of liver extracts isolated from several rats showed that oral administration of BCAA (0.75g/kg body weight (BW)) induced phosphorylation of 4E-BP1 and stimulated the enzymatic activity of p70 S6K. Both of these molecules act downstream of mTOR. From the results, we conclude that orally administrated BCAA augments albumin synthesis in the liver, not only by supplementation of material substrates for protein synthesis, but also by induction of an mTOR signal that is critical for translational initiation. Furthermore, we conclude that induction of mTOR signaling is one of the major pharmacological mechanisms by which BCAA granules reverse the hypoalbuminemia of cirrhotic patients.

Journal Article↗

PubMed1987

The protective effect of enriched branched chain amino acid formulation in the ischemic heart: a phosphorous-31 nuclear magnetic resonance study.

Branched chain amino acids (BCAA) have been found to have a protective effect on the ischemic myocardium. Isolated rat hearts were perfused with phosphate-free Krebs-Henseleit (KH) solution with or without BCAA. A Latex balloon-tipped catheter was inserted into the left ventricle to measure intracavitary pressures. Hearts were subjected to 18 minutes of 'no flow' global ischemia and then reperfused for 30 mins at 37 degrees C. Metabolism of high energy phosphates during ischemia and recovery was studied by P-31 NMR. Intracellular pH was calculated from the chemical shift of Pi. Pressure recovery was better with KH + BCAA (89 +/- 16%) than with KH (41 +/- 26%) (P = 0.0001); dP/dt recovery was also improved with BCAA (84 +/- 19% vs 27 +/- 27% for KH) (P = 0.0003). After 18 mins of ischemia, ATP levels in the BCAA group were higher than in the KH perfused hearts (33 +/- 20 vs 17 +/- 10% of pre-ischemic value) (P = 0.02). No significant difference was found in the intracellular pH at the end of the ischemic period. Following reperfusion the recovery of pH was better in the BCAA group (7.09 +/- 0.06 vs 7.04 +/- 0.06) (P = 0.03). These results show that BCAA protect the heart from myocardial ischemic injury, decrease depletion of ATP during ischemia, and enhance post-ischemic hemodynamic function.

Adenosine Triphosphate↗

PubMed2002

Double-blind crossover study of branched-chain amino acid therapy in patients with spinocerebellar degeneration.

To determine whether treatment with branched-chain amino acids (BCAA) can improve the condition of patients with ataxia, a double-blind crossover study of BCAA therapy was performed in 16 patients with spinocerebellar degeneration (SCD). The patients were treated with BCAA in oral doses of 1.5, 3.0, or 6.0 g or with placebo daily for 4 weeks in each study phase. The order of treatment phases (placebo or BCAA) was assigned randomly. An International Cooperative Ataxia Rating Scale (ICARS) was used to quantify the severity of symptoms of SCD. The mean ICARS score improved significantly with BCAA treatment compared with the mean pretreatment score (p<0.01). In addition, the improvement in the mean global ICARS score was significant in the middle-dose group compared with that in the placebo group (p<0.02). The estimated improvement in kinetic functions compared with pretreatment (p<0.01) was significant after treatment with BCAA, 1.5 and 3.0 g. All of the responders manifested predominantly cerebellar symptoms, especially those with spinocerebellar ataxia type 6 (SCA6). Thus, treatment with BCAA may be effective in patients with the cerebellar form of SCD.

Aged↗

PubMed2002

Relation between glutamine, branched-chain amino acids, and protein metabolism.

The branched-chain amino acids (BCAAs; valine, isoleucine, and leucine) are the major nitrogen source for glutamine and alanine synthesis in muscle. Synthesis of glutamine, alanine, and BCAA use is activated in critical illnesses such as in sepsis, cancer, and trauma. The use of glutamine often exceeds its synthesis, resulting in the lack of glutamine in plasma and tissues. In critical illness, resynthesis of BCAA from branched-chain keto acids is activated, particularly in hepatic tissue. The BCAA released to circulation may be used for protein synthesis or synthesis of alanine and glutamine. Glutamine and/or alanine infusion has an inhibitory effect on the breakdown of body proteins and decreases BCAA catabolism in postabsorptive control, endotoxemic, and irradiated rats. Decreased protein breakdown also was observed when glutamine synthesis was activated by ammonia infusion. In conclusion some favorable effects of BCAA supply can be explained by its role in the synthesis of glutamine and some positive effects of glutamine exogenous supply can be explained by its effect on metabolism of BCAA.

Alanine↗

PubMed2005

Effects of oral branched-chain amino acid granules on event-free survival in patients with liver cirrhosis.

BACKGROUND & AIMS: Nutritional intervention with branched-chain amino acid (BCAA) is reported to increase serum albumin concentration in patients with decompensated cirrhosis. However, a definite conclusion on whether it can improve patients' survival has not yet been reached. The present study aimed to test possibilities of improving survival of patients with decompensated cirrhosis by using a BCAA preparation that is suitable for long-term oral administration. METHODS: A multicenter, randomized, and nutrient intake-controlled trial on the comparative effects of BCAA orally administered at 12 g/day for 2 years versus diet therapy with defined daily food intake (1.0-1.4 g protein kg(-1) day(-1) including BCAA preparation and 25-35 kcal kg(-1) day(-1)) was conducted in 646 patients with decompensated cirrhosis. The primary end point was a composite of death by any cause, development of liver cancer, rupture of esophageal varices, or progress of hepatic failure (event-free survival). The secondary end points were serum albumin concentration and health-related quality of life (QOL) measured by Short Form-36 questionnaire. RESULTS: The incidence of events comprising the primary end point significantly decreased in the BCAA group as compared with the diet group (hazard ratio, 0.67; 95% confidence interval, 0.49-0.93; P = .015; median observation period, 445 days). Serum albumin concentration increased significantly in the BCAA group as compared with the diet group (P = .018). The "general health perception" domain in Short Form-36 measures was also improved (P = .003). Patients' adherence to the prescription was favorable. CONCLUSIONS: Oral supplementation with a BCAA preparation that can be administered for a long period improves event-free survival, serum albumin concentration, and QOL in patients with decompensated cirrhosis with an adequate daily food intake.

Administration, Oral↗

PubMed2000

Branched-chain amino acids.

The branched-chain amino acids (BCAA), isoleucine, leucine and valine, are unique in that they are principally metabolized extrahepatically in the skeletal muscle. This observation led to the investigation of these nutrients in a number of clinical scenarios. By far the most intensively studied applications for BCAA have been in patients with liver failure and/or patients in catabolic disease states. However, the resulting studies have not demonstrated a clear clinical benefit for BCAA nutritional supplements. In patients with liver failure, the BCAA did improve nitrogen retention and protein synthesis, but their effect on patient outcome was less clear. Similarly, in critically ill septic patients, BCAA did not improve either survival or morbidity. The BCAA are important nutrients, and it seems that any specific benefits associated with their use will be based upon a greater understanding of the underlying cellular biology. Potential areas of further research may include the combination of BCAA supplements with other anabolic factors (e.g. growth hormone) in managing patients with catabolic disease states.

Amino Acids, Branched-Chain↗

PubMed2006

Influence of branched-chain amino acid supplementation on urinary protein metabolite concentrations after swimming.

OBJECTIVE: The influence of branched-chain amino acid (BCAA) supplementation on urinary urea nitrogen, hydroxyproline (HP), and 3-methylhistidine (3MH) concentrations after 25 min of breast stroke exercise (65-70% maximum heart rate reserved, 65-70% HRRmax) followed by a 600 m crawl stroke competition was investigated in a double-blind, counter-balanced study. METHODS: Male university students (19-22 years old) majoring in physical education participated in the study. Based on the previous swimming time of a 600 m crawl stroke, the participants were divided into two groups: placebo (n = 9, BMI = 24.2 +/- 2.1 kg/m2; 12 g of glucose/day; in capsules) and BCAA (n = 10, BMI = 22.7 +/- 1.5 kg/m2; 12 g of BCAAs/day; in capsules: leucine 54%, isoleucine 19%, valine 27%) groups. The participants maintained a regular dietary intake (except the prescribed breakfast on day 15) and exercise activity at a moderate/low intensity (60-70% HRRmax, swimming and rowing, approximately 1.5 hour/day) during the 15-day study. A prescribed exercise program was performed on day 15. Urinary and blood samples were collected before, during, and after the prescribed exercise for the measurements of the urinary urea nitrogen, HP, and 3MH concentrations in urine, as well as the glucose, lactate, glutamine, alanine, and BCAA concentrations in plasma. RESULTS: Two weeks of dietary supplementation did not induce any changes in the plasma glucose and total BCAA concentrations of either group, nor in the urinary urea nitrogen, HP, and 3MH concentrations in urine. On day 15, after 25 min of breast stroke exercise and a 600 m crawl stroke competition, plasma glucose concentration decreased significantly (p < 0.05) whereas plasma lactate concentration increased significantly (p < 0.05) in both groups. The exercise program prescribed in the study did not affect urinary urea nitrogen, HP, and 3MH concentrations. Twenty hours after the competition, however, a significant increase in the concentrations of urinary urea nitrogen, HP, and 3MH was found in the placebo group (p < 0.05), but not in the BCAA group. CONCLUSIONS: The results obtained in this study suggest that swimming induced muscle proteolysis was prevented by BCAA supplementation. The mechanism could be attributed to the availability of ammonia provided by the oxidation of supplemented BCAAs during exercise.

Adult↗

PubMed1983

Effect of nutritional state and insulin on hind-limb amino acid metabolism in steers.

The effects of dietary protein level, exogenous insulin and starvation on amino acid (AA) uptake or release from the hindquarters of steers were studied. Irrespective of diet fed, physiologic state or time after feeding there was a net release of alanine and glutamine from hind limbs of steers. Steers from control 1 exhibited a net release of leucine, valine and isoleucine (branched-chain amino acids, BCAA) in the postabsorptive (prefeeding) state, but steers from control group 2 exhibited some BCAA uptake by the hind limb. At 2 and 4 hours postfeeding, there was marked net uptake by hind limbs of BCAA and total AA in steers fed the control (12.8% protein) diets. At 2 and 4 hours after feeding there was slight hind-limb uptake of BCAA and total AA in steers fed the low protein diet, while there was a massive uptake of BCAA and total AA by hind limbs of steers fed the high protein diet. Upon insulin injection to postabsorptive steers, BCAA and total AA uptake by hind limbs was markedly stimulated at 1 and 2 hours, but by 4 hours the AA flux pattern had reverted to that in the postabsorptive state. After 24 and 48 hours of starvation, steer hindquarters released significant quantities of BCAA, essential amino acids and total amino acids.

Amino Acids↗

PubMed1986

Respective contribution of plasma branched-chain amino acids and 2-keto acids to the hepatic metabolism of the carbon moiety of branched-chain amino acids in fed rats.

The splanchnic balances of branched-chain amino acids (BCAA) and ketoacids (BCKA) concentrations were compared in rats fed a 15% (basal) or a 70% (HP) casein diet. Arterial BCAA concentrations were four- to fivefold and BCKA concentrations were twofold higher in rats fed HP diet than in rats fed basal diet. In rats fed basal diet, a higher proportion (45-58%) of BCKA was removed by the liver than of BCAA (7-12%). Thus, plasma BCKA were probably the major source of substrates for hepatic BCKA dehydrogenase. In rats fed HP diet, hepatic uptake of BCAA was 10 times greater than in rats fed basal diet, owing to their higher extraction; BCKA uptake was only twice as great; thus BCKA were a minor source of substrates for hepatic metabolism. In both diet groups, uptake of ketomethylvalerate (KMV) was less efficient than ketoisovalerate (KIV) or ketoisocaproate (KIC) uptake. Studies of metabolism of intraportal loads of BCKA showed that capacities for KIV and KIC uptake were high, KMV uptake plateaued at lower portal concentrations. With HP diets, the liver may be the major site of BCAA utilization; the interorgan transfer of the carbon moiety of BCAA to the liver as ketoacids does not keep pace with an increased availability of BCAA.

Amino Acids, Branched-Chain↗

PubMed1989

Activities of branched-chain amino acid--degrading enzymes in liver from rats fed different dietary levels of protein.

The relationships among dietary protein intake, plasma branched-chain amino acid (BCAA) and keto acid (BCKA) concentrations, and liver BCAA-degrading enzyme activities were investigated in rats fed, for 5 h/d for 2, 6 or 9 d, diets containing from 0 to 50% casein. Plasma, liver and muscle BCAA concentrations were proportional to protein intake over the entire range tested; plasma BCKA concentration, however, was proportional only in the range from 0 to 20% casein, after which a plateau was reached. By d 2, liver cytosolic BCAA aminotransferase activity had increased in rats fed 50% casein; by d 9, activity had increased in rats fed 0 or 5% casein as well. Liver mitochondrial BCAA aminotransferase activity was unresponsive to dietary treatment. Basal liver BCKA dehydrogenase activity and the percent active complex were proportional to protein intake on d 2 and 6. On d 2, total BCKA dehydrogenase activity was the same in all groups; by d 6, total activity had increased in rats fed 30 or 50% casein. We conclude that although the adaptive changes in BCAA-degrading enzyme activities are small, they are sufficient to compensate for excessively high or low protein intakes, so that tolerable concentrations of BCAA and BCKA are maintained.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed1991

Branched-chain and other amino acids in tissues of rats fed leucine-limiting amino acid diets containing norleucine.

Amino acid concentrations were measured in plasma, brain, muscle and liver from rats fed leucine-limiting diets containing varying proportions of other indispensable amino acids (IAA), the branched-chain amino acids (BCAA) and norleucine, a BCAA analog known to compete with large neutral amino acids (LNAA) for transport into tissues. Leucine was low and other IAA were high when dietary IAA were 125% and leucine was 65% of requirements; higher leucine and lower IAA concentrations occurred when dietary IAA were 75% of requirements. Tissue leucine was high and isoleucine and valine were low in rats fed excess leucine. Norleucine induced dose-dependent reductions in BCAA, especially in brain and muscle in which isoleucine or valine were sometimes undetectable. Leucine was not depressed further when control values were low as in the rats fed 125% IAA. Norleucine frequently prevented the high BCAA found after feeding additional BCAA. Other LNAA tended to be low in the brain and muscle of rats fed norleucine. Lysine was high only in the tissues of rats fed 75% IAA and norleucine; this effect was prevented when added leucine was given. Brain tryptophan, but not always serotonin, was low in rats fed norleucine. The results show transport-related, selective and usually marked depletions of tissue BCAA in rats fed norleucine; this suggests norleucine may be an aid in the treatment of clinical conditions involving excesses of BCAA.

Amino Acids, Branched-Chain↗

PubMed1996

Oral supplementation with branched-chain amino acids improves transthyretin turnover in rats with carbon tetrachloride-induced liver cirrhosis.

The hypothesis that dietary branched-chain amino acid (BCAA) supplementation improves the impaired protein turnover in male Donryu rats with carbon tetrachloride-induced liver cirrhosis was tested. We supplemented cirrhotic rats orally for 2 wk with BCAA solution [26.67 mg BCAA/(100 g body weight . d)], a conventional amino acid mixture [4.25 mg BCAA/(100 g body weight . d)] or saline and fed these three groups the AIN76 basal diet to have similar intakes of total energy and total nitrogen. Normal rats without liver cirrhosis were fed the basal diet similar to the above (noncirrhotic controls). After supplementation, rats were fed intravenous transthyretin (thyroxine-binding prealbumin) doubly labeled with 125I-tyramine-cellobiose and 131I. Kinetic indices including production rate of transthyretin were analyzed from plasma transthyretin disappearance curves. Tissue sites of transthyretin degradation were assayed using a trapped ligand technique by measuring 125I-tyramine-cellobiose levels. The production rate of transthyretin was significantly lower in cirrhotic rats supplemented with saline (mean 25.46 X 10(-3) . h(-1)) compared with noncirrhotic controls (45.08 X 10(-3) . h(-1)) (P < 0.05). This was corrected by supplementing cirrhotic rats with BCAA (37.05 X 10(-3) . h(-1), P < 0.05) but not with conventional amino acid mixture (22.49 X 10(-3) . h(-1)). The accelerated degradation of transthyretin in muscles of cirrhotic rats was improved by BCAA (P < 0.05). In conclusion, dietary supplementation with BCAA improves the impaired transthyretin turnover in rats with liver cirrhosis.

Administration, Oral↗

PubMed2004

Parenteral and enteral routes of feeding in neonatal piglets require different ratios of branched-chain amino acids.

The requirements for total branched-chain amino acids (BCAA), isoleucine, leucine and valine, in neonatal piglets receiving parenteral and enteral nutrition was determined recently. The optimum ratio among BCAA during different routes of feeding is not yet known. In this study, the ratio of BCAA during parenteral and enteral feeding was tested using the indicator amino acid oxidation (IAAO) technique. Male Yorkshire piglets (n=24) received amino acid-based diets containing adequate nutrients for 5 d. Phenylalanine oxidation and kinetics were determined from a 4-h primed, constant infusion of L-[1-14C]-phenylalanine on d 6 and 8. On d 6, all piglets received a BCAA diet which met 75% of the total BCAA requirement, based on our previous research, with a ratio of 1:1.8:1.2 of isoleucine/leucine/valine. On d 8, the piglets were randomly assigned to receive one of the 3 test diets supplemented with isoleucine (+isoleucine), leucine (+leucine) or valine (+valine) to meet 100% of requirement, with the remaining two BCAA at 75% of requirement. The difference in phenylalanine oxidation (% of dose) between d 6 and 8 was used as an indicator of BCAA adequacy. In enterally fed piglets, the change in the percentage of the dose oxidized was minimal for all 3 test diets (mean=1.15%). In parenterally fed piglets, the difference in phenylalanine oxidation (% of dose) between d 6 and 8 was +isoleucine (12.6%), +leucine (2%) and +valine (6.6%). The ratio of 1:1.8:1.2 of isoleucine/leucine/valine is appropriate for enteral feeding, but during parenteral feeding, isoleucine was first limiting and valine was second limiting.

Amino Acids, Branched-Chain↗

PubMed2005

Interrelationship between physical activity and branched-chain amino acids.

Some athletes can have quite high intakes of branched-chain amino acids (BCAAs) because of their high energy and protein intakes and also because they consume protein supplements, solutions of protein hydrolysates, and free amino acids. The requirement for protein may actually be higher in endurance athletes than in sedentary individuals because some amino acids, including the BCAAs, are oxidized in increased amounts during exercise compared with rest, and they must therefore be replenished by the diet. In the late 1970s, BCAAs were suggested to be the third fuel for skeletal muscle after carbohydrate and fat. However, the majority of later studies, using various exercise and treatment designs and several forms of administration of BCAAs (infusion, oral, and with and without carbohydrates), have failed to find a performance-enhancing effect. No valid scientific evidence supports the commercial claims that orally ingested BCAAs have an anticatabolic effect during and after exercise in humans or that BCAA supplements may accelerate the repair of muscle damage after exercise. The recommended protein intakes for athletes (1.2 to 1.8 g . kg body mass(-1) . d(-1)) do not seem to be harmful. Acute intakes of BCAA supplements of about 10-30 g/d seem to be without ill effect. However, the suggested reasons for taking such supplements have not received much support from well-controlled scientific studies.

Adult↗

PubMed2006

Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise.

BCAAs (leucine, isoleucine, and valine), particularly leucine, have anabolic effects on protein metabolism by increasing the rate of protein synthesis and decreasing the rate of protein degradation in resting human muscle. Also, during recovery from endurance exercise, BCAAs were found to have anabolic effects in human muscle. These effects are likely to be mediated through changes in signaling pathways controlling protein synthesis. This involves phosphorylation of the mammalian target of rapamycin (mTOR) and sequential activation of 70-kD S6 protein kinase (p70 S6 kinase) and the eukaryotic initiation factor 4E-binding protein 1. Activation of p70 S6 kinase, and subsequent phopsphorylation of the ribosomal protein S6, is associated with enhanced translation of specific mRNAs. When BCAAs were supplied to subjects during and after one session of quadriceps muscle resistance exercise, an increase in mTOR, p70 S6 kinase, and S6 phosphorylation was found in the recovery period after the exercise with no effect of BCAAs on Akt or glycogen synthase kinase 3 (GSK-3) phosphorylation. Exercise without BCAA intake led to a partial phosphorylation of p70 S6 kinase without activating the enzyme, a decrease in Akt phosphorylation, and no change in GSK-3. It has previously been shown that leucine infusion increases p70 S6 kinase phosphorylation in an Akt-independent manner in resting subjects; however, a relation between mTOR and p70 S6 kinase has not been reported previously. The results suggest that BCAAs activate mTOR and p70 S6 kinase in human muscle in the recovery period after exercise and that GSK-3 is not involved in the anabolic action of BCAAs on human muscle.

Amino Acids, Branched-Chain↗

PubMed2006

Therapeutic use of branched-chain amino acids in burn, trauma, and sepsis.

Various experimental studies conducted in the 1970s demonstrated, at least in the physiological situation, the anabolic and/or anticatabolic properties of branched-chain amino acids (leucine, valine, isoleucine) or their ketoacid derivatives. This led to several clinical studies in the late 1970s and early 1980s that aimed to evaluate the potential benefits of BCAA supplementation in nutritional support of the critically ill. The data on burn, trauma, and sepsis are, however, far from convincing. Besides significant discrepancies in their results and the fact that most of these studies involved very small populations of patients, few of them meet the current standards of therapeutic evaluation. However, some positive results in specific studies suggest that the underlying concept may be correct but that interpretation has been faulty. Indeed, we know now that while the BCAAs possess regulatory properties on protein metabolism, leucine is by far the most potent, while isoleucine and valine are inefficient. However, in the above-mentioned studies, BCAA-supplemented nutrition very frequently supplied almost equivalent amounts of all 3 BCAAs. Moreover, several studies were performed without adequate basal nutritional support, which most probably hampered the correct metabolic utilization of these amino acids. Taken together, these factors mean that the demonstrations of BCAA efficacy were fortunate in the least. In contrast, more recently, leucine was demonstrated to positively affect protein synthesis in an experimental model of sepsis or burn. In parallel, 2 prospective controlled trials of BCAA supplementation in septic patients also demonstrated an improvement in patients' nutritional status and outcome. Thus, we should abandon the concept of BCAA-supplemented nutrition for a more promising leucine-supplemented nutrition that requires further evaluation.

Amino Acids, Branched-Chain↗

PubMed1999

Contribution of branched-chain amino acids to uteroplacental ammonia production in sheep.

The uteroplacental tissues are a principal site of ammonia production for the conceptus. The goal of this study was to examine the effect of the composition of maternal amino acid (AA) infusate on uteroplacental ammonia production. Seven pregnant ewes (126 +/- 1. 4 days gestation) were infused through the maternal femoral vein (duration 3.5 h, rate 240 ml per hour) with three solutions of AAs. The first infusate was comparable to commercial parenteral nutrition preparations, the second infusate contained the same solution without branched-chain AAs (BCAAs), and the third infusate contained only BCAAs. Blood samples were simultaneously collected from the maternal artery, uterine vein, fetal artery, and umbilical vein to determine plasma AA concentrations and whole blood ammonia concentrations, before (control) and 2 h after (experimental) the start of infusion. Uterine and umbilical blood flows were measured using the ethanol steady-state diffusion method. Results showed that fetal arterial and venous ammonia concentrations increased significantly after infusions with all AAs or only BCAAs, but not without BCAAs. Uteroplacental ammonia production increased in response to each of the three infusates. However, this increase was much greater when the BCAAs were present in infusates. We conclude that there is a significant contribution of BCAAs to the uteroplacental ammonia production. Maternal AA infusions containing BCAAs can result in increased fetal blood ammonia concentrations.

Amino Acids, Branched-Chain↗

PubMed2005

Update on branched-chain amino acid supplementation in liver diseases.

PURPOSE OF REVIEW: Branched-chain amino acids (BCAAs) have a peculiar role in whole-body nitrogen metabolism. BCAAs are a substrate for protein synthesis, and have been used to conserve or restore muscle mass in advanced liver disease. In addition, the competitive action of BCAAs on amino acid transport across the blood-brain barrier may improve hepatic encephalopathy. RECENT FINDINGS: The effects of branched-chain amino acids on nutrition and ultimately on prognosis of patients with advanced cirrhosis have been confirmed in a large multicenter, long-term trial. Similarly, BCAA treatment improved the prognosis of patients with hepatocellular carcinoma, treated by chemoembolization. The mechanism for the beneficial effects of BCAA is likely to depend on the stimulating activity of BCAA on hepatocyte growth factor, favoring liver regeneration. SUMMARY: After an experience of 25 years with branched-chain amino acids, new data supports their beneficial effect in liver diseases. Although the number of patients who cannot tolerate dietary proteins in amounts sufficient to meet their increased catabolism is probably low, in this specific setting BCAAs remain the sole treatment of proved efficacy.

Amino Acids, Branched-Chain↗