Effects of branched-chain amino acids and zinc-enriched nutrients on prognosticators in HCV-infected patients: A multicenter randomized controlled trial
- Authors:
- Published online on: November 13, 2014 https://doi.org/10.3892/mmr.2014.2943
- Pages: 2159-2166
Abstract
Introduction
The liver plays a central role in nutritional metabolism and, therefore, metabolic disorders, including amino acid imbalances and trace element deficiencies, occur frequently in patients with chronic liver disease (1). Branched-chain amino acids (BCAAs) are essential amino acids that play a crucial role in albumin synthesis and ammonia detoxification in patients with cirrhosis (2). In the clinical setting, reductions in serum BCAA levels can be assessed by measurement of the serum BCAA-to-tyrosine ratio (BTR) (1). Low serum BTR, along with low serum albumin levels, have recently been reported to be a predictive factor in the development of hepatocellular carcinoma (HCC), and confer a poor prognosis in patients with cirrhosis (3,4).
Zinc is a trace element that activates >300 metalloenzymes, including DNA polymerase (5). In addition, zinc stabilizes zinc finger proteins, which bind to DNA and modulate the transcription of target genes, including tumor suppressor genes (6). In patients with chronic liver disease, serum zinc levels decrease as the severity of liver disease increases (7), and low serum zinc levels are known to be associated with the development of HCC and poor prognosis in hepatitis C virus (HCV)-infected patients (8,9). Thus, serum zinc levels are a significant metabolic prognosticator in HCV-infected patients.
BCAAs and zinc are pharmacological nutrients that exert diverse biological effects (1). A decreased risk of hepatocarcinogenesis and mortality has been reported in patients with chronic liver disease treated with BCAA (4,10,11) or zinc (8,9) supplementation. Therefore, a supplement containing both BCAAs and zinc may have the potential to improve prognostic factors in patients with chronic liver disease. Aminofeel® is a commercially available BCAA and zinc-enriched supplement. We previously examined the usefulness of the supplement and demonstrated that it improves insulin resistance, taste sensitivity and adherence to interferon therapy in HCV-infected patients (12–16). However, it remains unclear whether BCAA and zinc-enriched supplementation improves prognostic factors, including the platelet count, serum albumin levels, homeostasis model assessment for insulin resistance (HOMA-IR) value, serum BTR and zinc levels in HCV-infected patients. In addition, to the best of our knowledge, the impact of the supplement on serum α-fetoprotein (AFP) levels has never been investigated. Therefore, we performed a prospective multicenter randomized controlled trial to investigate the effects of a BCAA and zinc-enriched supplement on prognostic factors in HCV-infected patients.
Subjects and methods
Ethical considerations
This study was designed in 2009 by the steering committee of Research on Hepatitis, The Ministry of Health, Labour and Welfare of Japan (principal investigator, Michio Sata, MD), to evaluate the usefulness of BCAA and zinc supplementation in patients with chronic HCV infection. The study protocol was approved by the Ethical Committee of Human Experimentation in Kurume University School of Medicine (approval no. 09152, UMIN000012815), and is in accordance with the Helsinki Declaration of 1975, as revised in 1983. Written informed consent for participation in the study was obtained from each subject.
Subjects
HCV-infected patients aged 65 years or older who had serum albumin levels ≥3.5 and <4.0 g/dl were recruited for the study. The exclusion criteria were as follows: i) currently undergoing interferon therapy; ii) positivity for hepatitis B surface antigen or serum hepatitis B virus DNA; iii) presence of autoimmune hepatitis, alcoholic liver disease (ethanol consumption >50 g/day), primary biliary cirrhosis, primary sclerosing cholangitis, hemochromatosis or Wilson’s disease; iv) presence of cardiac or renal disease or severe psychiatric disease; v) presence of HCC or within a year of treatment for HCC; vi) presence of esophageal or gastric varices at risk of rupture; vii) presence of diabetes mellitus with anti-diabetic medication; viii) history of consumption of the BCAA and zinc-enriched supplement; ix) having taken a BCAA-related medication or a BCAA-containing supplement within the preceding 90 days; and x) currently taking a trace element-related medication or a trace element-containing supplementation.
Study design and participants
We performed a prospective multicenter randomized controlled trial in an outpatient setting in six medical institutions in Japan. From 2010 to 2012, 54 HCV-infected patients who fulfilled the inclusion criteria were enrolled in the study. One patient withdrew consent for participation before randomization. The stratified randomization method was used to achieve balance among groups in terms of subjects’ baseline characteristics. Randomization was performed centrally, and both patients and investigators were blinded to the patients’ group assignment. The patients were allocated at a 1:1 ratio to the placebo (n=27) or supplement group (n=26). Two patients in the placebo group were withdrawn from the study due to withdrawal of consent (n=1) and anemia (n=1). Two patients in the supplement group were withdrawn due to general fatigue (n=1) and the appearance of a rash (n=1). Thus, four patients were excluded from the statistical analysis on day 60 owing to lack of data. Finally, 92.6% (25/27) of the patients in the placebo group (age, 74±5 years; female/male, 17/8) and 92.3% (24/26) of patients in the supplement group (age, 74±5 years, female/male, 15/9) completed the 60-day treatment period, and the efficacy and safety of the treatment were assessed (Fig. 1).
Intervention and assessment protocols
In the supplement group, the patients were given two sachets of the BCAA and zinc-enriched supplement containing 6,400 mg/day BCAAs and 10 mg/day zinc (Aminofeel, Seikatsu Bunkasya Co., Inc., Chiba, Japan), once after breakfast and again at bedtime (Fig. 2). In the placebo group, the patients were administered a sachet of placebo after breakfast and another at bedtime. Although the BCAAs, trace elements and vitamins were replaced with corn starch in the placebo (Table I), the appearance and taste of the placebo were similar to those of the supplement.
 | Table IContents of one sachet of placebo and one sachet of the branch-chain amino acid and zinc-enriched supplement. |
On days 0 and 60, we evaluated body mass index (BMI), subjective symptoms (fatigue, sleeplessness, muscle cramps, loss of appetite and taste disorders) using a visual analog scale (Fig. 2). A visual analog scale is a horizontal line, 100 mm in length, anchored by word descriptors for subjective symptoms at each end. The patients marked on the line the point that they felt represented their current subjective symptom. The visual analog scale score was determined by measuring the distance (in mm) from the left-hand end of the line to the point that the patient had marked, on which 0 mm indicates an absence of symptoms and 100 mm indicates the worst symptom.
The following blood biochemical parameters were measured in all the patients on days 0 and 60: White blood cell count, hemoglobin levels, platelet count, total protein levels, albumin levels, BTR, prothrombin time (international normalized ratio), ammonia levels, zinc levels, fasting blood glucose levels, hemoglobin A1c levels, fasting immune reactive insulin levels, HOMA-IR, total cholesterol levels, aspartate aminotransferase levels, alanine aminotransferase levels, γ-glutamyl transpeptidase levels, alkaline phosphatase levels, blood urea nitrogen levels, creatinine levels, AFP levels and HCV RNA levels. All the biochemical parameters were measured by standard clinical methods using venous blood samples taken the morning after a 12-h overnight fast, as previously described (17).
Outcomes
The primary outcomes were the following known prognostic factors for patients with chronic liver disease: Platelet count, serum albumin levels, serum AFP levels, HOMA-IR value, serum BTR and serum zinc levels. The secondary outcomes were BMI, subjective symptoms and biochemical examinations, including liver and renal functions, glucose metabolism and HCV RNA levels.
Stratification analysis according to serum AFP levels
As the serum AFP levels had a wide distribution, we performed a stratification analysis to assess the effects of the BCAA and zinc-enriched supplement on changes in serum AFP levels. The patients in both the placebo and supplement groups were further classified into two groups based on their serum AFP levels at baseline as follows: One group with AFP levels within the reference range (≤8.7 ng/ml) and another group with elevated serum AFP levels (>8.7 ng/ml). Changes in serum AFP levels were expressed as ΔAFP (day 60 AFP level vs. day 0 AFP level).
Safety monitoring
Safety was assessed in terms of vital signs, physical examination results, laboratory test results and clinical adverse events. When 19 patients (n=9 in the placebo group; n=10 in the supplement group) had completed the study, the data monitoring committee evaluated the safety and disadvantages of the groups and confirmed that there were no severe adverse events or disadvantages observed in either the placebo or supplement group. This evaluation was conducted to produce an interim report at the meeting of Research on Hepatitis (Ministry of Health, Labour and Welfare of Japan; principal investigator, Michio Sata).
Considerations relating to the sample size and treatment period
Based on the BTR data in our previous pilot study (12), the sample size was calculated using Power and Sample Size Calculation v 3.0, as previously described (18). Briefly, we planned to study a continuous response variable in independent controls and experimental subjects with one control per experimental subject. In our previous pilot study, the response within each subject group was normally distributed with a standard deviation of 0.9 (12). If the true difference between the experimental and control means is 1, we would need to study a total of 36 subjects (18 experimental subjects and 18 control subjects) to be able to reject the null hypothesis that the population means of the experimental and control groups are equal with a probability (power) of 0.9. The type I error probability associated with testing this null hypothesis is 0.05.
The treatment period was also based on BTR data from our previous pilot study (12). In the previous study, we examined the effects of the BCAA and zinc-enriched supplement on serum BTR 30, 60 and 90 days after treatment. Considering that the most significant efficacy was observed 60 days after treatment, a 60-day treatment period was used in this study (12).
Statistical analysis
All the data are expressed as the number or mean ± standard deviation. Differences between the placebo and supplement groups were analyzed using the χ2 test or Mann-Whitney U test. Statistical comparisons between multiple groups were performed using the Kruskal-Wallis test. P<0.05 was considered to indicate a statistically significant difference. All analyses were performed using JMP 10.0.2 (SAS Institute Inc., Cary, NC, USA).
Results
Patient characteristics
At baseline, there were no significant differences in age, gender and BMI between the placebo and supplement groups (Table II). No significant differences were observed in any subjective symptoms, including fatigue, sleeplessness, muscle cramps, loss of appetite and taste disorders between the two groups (Table II).
There were no significant differences in any of the prognostic factors, including platelet count, serum albumin and AFP levels, HOMA-IR value, serum BTR and serum zinc levels between the two groups (Table II). Moreover, no significant difference was observed in any of the biochemical examinations, including tests for liver and renal function, glucose metabolism and HCV RNA levels, between the groups at baseline (Table II).
Effects of BCAA and zinc-enriched supplementation on primary outcomes
On day 60, we evaluated the effects of the BCAA and zinc-enriched supplementation on the prognostic factors in the HCV-infected patients. There were no significant differences in platelet count, serum albumin and AFP levels, and HOMA-IR value between the placebo and supplement groups (Fig. 3A–D). Conversely, a significant increase in serum BTR was observed in the supplement group compared with the placebo group (Fig. 3E). In addition, a significant increase was observed in serum zinc levels in the supplement group compared with the placebo group (Fig. 3F).
Effects of the BCAA and zinc-enriched supplementation on secondary outcomes
On day 60, we also evaluated the effects of the BCAA and zinc-enriched supplement on BMI, subjective symptoms and biochemical parameters in the HCV-infected patients. There was no significant difference in BMI between the placebo and supplement groups (Table III). There was also no significant difference in fatigue, sleeplessness, muscle cramps, loss of appetite or taste disorders between the groups (Table III).
| Table IIIEffects of the branch-chain amino acid and zinc-enriched supplement on body mass index and subjective symptoms. |
There was no significant difference in liver function test results, renal function test results, glucose metabolism or blood ammonia levels between the placebo and supplement groups (Table IV). In addition, no significant difference in HCV RNA levels was observed between the two groups (Table IV).
| Table IVEffects of the branch-chain amino acid and zinc-enriched supplement on biochemical examinations. |
Stratification analysis according to serum AFP levels at baseline
As the serum AFP levels were widely distributed, a stratification analysis was performed according to the serum AFP levels at baseline to assess the effects of BCAA and zinc-enriched supplementation on changes in the serum AFP levels. A significant reduction in the ΔAFP levels was observed in the supplement group with an elevation in the AFP levels compared with the other groups (Fig. 4).
Safety
The incidence rates of adverse events during the study were 3.7% (1/27) and 7.7% (2/26) in the placebo and supplement groups, respectively. Two subjects discontinued the placebo due to withdrawal of consent (n=1) and anemia (Grade 2; n=1). Two subjects in the supplement group discontinued the treatment due to general fatigue (Grade 2; n=1) and rash (Grade 3; n=1). There was no significant deterioration in any biochemical parameters including liver and renal function. No Grade 4 or higher adverse events occurred during the study period.
Discussion
This was a multicenter randomized controlled trial designed to examine the effects of a BCAA and zinc-enriched supplement on prognostic factors in HCV-infected patients. No changes were observed in the platelet counts, serum albumin levels or HOMA-IR values; however, a significant increase was noted in the serum BTR and zinc levels in the patients administered the supplement for 60 days. Furthermore, the stratification analysis revealed a significant reduction in the ΔAFP levels in the supplement group with an elevation in the AFP levels compared with the other groups.
No significant increase was observed in the serum albumin levels in this study. However, to the best of our knowledge, we demonstrated for the first time that 6,400 mg/day BCAAs administered for 60 days was sufficient to increase the serum BTR in patients in the early stages of HCV-related chronic liver disease. The dose of BCAAs used in this study may have been insufficient to increase serum albumin levels over the period of 60 days. However, a lower serum BTR can predict decreases in serum albumin levels (19), suggesting that long-term administration of the supplement may maintain constant serum albumin levels. In addition, low serum BTRs have been recently reported to be a predictive factor in the development of HCC, intrahepatic distant recurrence of HCC and poor prognosis in patients with cirrhosis (2,3). Moreover, BCAA supplementation is known to increase serum BTR, leading to the suppression of hepatocarcinogenesis and improvement in survival in patients with cirrhosis (4,10,11). Taken together, it would be worthwhile to test the effect of the long-term administration of the supplement on hepatocarcinogenesis and prognosis in HCV-infected patients.
We also demonstrated that the administration of 10 mg/day zinc was sufficient to increase the serum zinc levels in patients in the early stages of HCV-related chronic liver disease. In patients with cirrhosis, zinc upregulates hepatic ornithine transcarbamylase activity, a key enzyme in the urea cycle, and enhances hepatic ammonia detoxification (20). A recent meta-analysis by Chavez-Tapia et al (21) demonstrated that oral zinc supplementation improved performance in the number connection test, a test for hepatic encephalopathy. Thus, the supplement tested here may be beneficial for patients with hyperammonemia. In addition, a decrease in serum zinc levels is known to predict the development of HCC and poor prognosis in HCV-infected patients (8,9). Moreover, decreased risks of hepatocarcinogenesis and mortality have been observed in HCV-infected patients with increased serum zinc levels owing to zinc supplementation (8,9). The data reported here indicate that the zinc-enriched supplement has the potential to suppress the onset of HCC and improve prognosis in HCV-infected patients.
When all of the data were analyzed, the serum AFP levels were not significantly decreased in the patients administered the BCAA and zinc-enriched supplement. However, the stratification analysis revealed a significant reduction in the ΔAFP levels in the supplement group with elevated AFP levels at baseline compared with the other groups. Although the reasons for the supplement-induced reductions in serum AFP levels are unclear, our findings are supported by previously published studies. First, Hagiwara et al (22) reported that BCAAs induce apoptosis in HCC cell lines by promoting a negative feedback loop from the mammalian target of rapamycin complex 1/S6K1 to the PI3K/Akt pathway and by suppressing the mammalian target of rapamycin complex 2 kinase activity towards Akt. Second, zinc stabilizes zinc finger proteins, which bind to DNA, and Nakao et al, as well as Xie et al, reported that zinc fingers and homeoboxes 2 and zinc finger and BTB domain-containing protein 20 repress the postnatal expression of AFP by interacting with the AFP gene promoter regions (23,24). Thus, BCAAs and zinc may independently contribute to a reduction in serum AFP levels by causing apoptosis of hepatoma cells and repressing AFP expression.
In this study, the BCAA and zinc-enriched supplement did not affect the platelet count, HOMA-IR value or HCV RNA levels. Conversely, previous basic studies demonstrated that valine, a BCAA, increased blood platelet counts in carbon tetrachloride-treated cirrhotic rats (25). Leucine and isoleucine have been shown to improve insulin resistance in mice fed a high-fat diet (26,27). Valine has been shown to suppress HCV genome replication in a dose-dependent manner (28). Although the reason for the discrepancy between these previous studies and our study remains unknown, BCAAs may exert beneficial effects on the platelet count, HOMA-IR value and serum HCV RNA levels only under specific conditions. We also demonstrated that no subjective symptoms were significantly improved by the BCAA and zinc-enriched supplementation. BCAAs and zinc have been previously reported to improve muscle cramps and taste disorders (16,29,30), respectively. However, these symptoms were mild in the study subjects at baseline. This may explain why significant changes in muscle cramps and taste disorders were not evident in this study.
In conclusion, we examined the effects of a BCAA and zinc-enriched supplement on prognostic factors in HCV-infected patients. There were no significant changes in platelet count, serum albumin levels or HOMA-IR values. However, serum BTR and zinc levels were significantly improved by the supplementation. In addition, a stratification analysis revealed a significant reduction in ΔAFP levels in the supplement group, with an increase in AFP levels compared with the other groups. In light of these results, we conclude that the BCAA and zinc-enriched supplement may improve prognosis in HCV-infected patients by improving amino acid imbalance, reducing zinc deficiencies and partly downregulating AFP expression.
Acknowledgements
The authors thank Dr Tatsuya Ide (Kurume University School of Medicine), Dr Tatsuo Kanda (Chiba University) and Dr Makoto Arai (Chiba University) for the collection of data.
Abbreviations:
|
BCAAs |
branched-chain amino acids |
|
BTR |
BCAA-to-tyrosine ratio |
|
HCC |
hepatocellular carcinoma |
|
HCV |
hepatitis C virus |
|
HOMA-IR |
homeostasis model assessment for insulin resistance |
|
AFP |
α-fetoprotein |
|
BMI |
body mass index |
References
|
Kawaguchi T, Izumi N, Charlton MR and Sata M: Branched-chain amino acids as pharmacological nutrients in chronic liver disease. Hepatology. 54:1063–1070. 2011. View Article : Google Scholar : PubMed/NCBI | |
|
Kawaguchi T, Taniguchi E and Sata M: Effects of oral branched-chain amino acids on hepatic encephalopathy and outcome in patients with liver cirrhosis. Nutr Clin Pract. 28:580–588. 2013. View Article : Google Scholar : PubMed/NCBI | |
|
Ishikawa T, Kubota T, Horigome R, Kimura N, Honda H, Iwanaga A, et al: Branched-chain amino acids to tyrosine ratio (BTR) predicts intrahepatic distant recurrence and survival for early hepatocellular carcinoma. Hepatogastroenterology. 60:2013.PubMed/NCBI | |
|
Kawaguchi T, Shiraishi K, Ito T, Suzuki K, Koreeda C, Ohtake T, et al: Branched-chain amino acids prevent hepatocarcinogenesis and prolong survival of patients with cirrhosis. Clin Gastroenterol Hepatol. in press. 2014. View Article : Google Scholar | |
|
Auld DS, Kawaguchi H, Livingston DM and Vallee BL: RNA-dependent DNA polymerase (reverse transcriptase) from avian myeloblastosis virus: a zinc metalloenzyme. Proc Natl Acad Sci USA. 71:2091–2095. 1974. View Article : Google Scholar : PubMed/NCBI | |
|
Kumar R, Manning J, Spendlove HE, Kremmidiotis G, McKirdy R, Lee J, et al: ZNF652, a novel zinc finger protein, interacts with the putative breast tumor suppressor CBFA2T3 to repress transcription. Mol Cancer Res. 4:655–665. 2006. View Article : Google Scholar : PubMed/NCBI | |
|
Moriyama M, Matsumura H, Fukushima A, Ohkido K, Arakawa Y, Nirei K, et al: Clinical significance of evaluation of serum zinc concentrations in C-viral chronic liver disease. Dig Dis Sci. 51:1967–1977. 2006. View Article : Google Scholar : PubMed/NCBI | |
|
Katayama K, Sakakibara M, Imanaka K, Ohkawa K, Matsunaga T, Naito M, et al: Effect of zinc supplementation in patients with type C liver cirrhosis. O J Gas. 1:22–28. 2011. | |
|
Matsumura H, Nirei K, Nakamura H, Arakawa Y, Higuchi T, Hayashi J, et al: Zinc supplementation therapy improves the outcome of patients with chronic hepatitis C. J Clin Biochem Nutr. 51:178–184. 2012.PubMed/NCBI | |
|
Muto Y, Sato S, Watanabe A, Moriwaki H, Suzuki K, Kato A, et al: Effects of oral branched-chain amino acid granules on event-free survival in patients with liver cirrhosis. Clin Gastroenterol Hepatol. 3:705–713. 2005. View Article : Google Scholar : PubMed/NCBI | |
|
Muto Y, Sato S, Watanabe A, Moriwaki H, Suzuki K, Kato A, et al: Overweight and obesity increase the risk for liver cancer in patients with liver cirrhosis and long-term oral supplementation with branched-chain amino acid granules inhibits liver carcinogenesis in heavier patients with liver cirrhosis. Hepatol Res. 35:204–214. 2006.PubMed/NCBI | |
|
Kawaguchi T, Nagao Y, Matsuoka H, Ide T and Sata M: Branched-chain amino acid-enriched supplementation improves insulin resistance in patients with chronic liver disease. Int J Mol Med. 22:105–112. 2008.PubMed/NCBI | |
|
Kawaguchi T, Taniguchi E, Itou M, Sumie S, Oriishi T, Matsuoka H, et al: Branched-chain amino acids improve insulin resistance in patients with hepatitis C virus-related liver disease: report of two cases. Liver Int. 27:1287–1292. 2007.PubMed/NCBI | |
|
Nagao Y, Kawaguchi T, Ide T and Sata M: Effect of branched-chain amino acid-enriched nutritional supplementation on interferon therapy in Japanese patients with chronic hepatitis C virus infection: a retrospective study. Virol J. 9:2822012. View Article : Google Scholar : PubMed/NCBI | |
|
Nagao Y, Kawaguchi T, Kakuma T, Ide T and Sata M: Post-marketing surveillance study for efficacy and safety of Aminofeel®, a branched chain amino acids-enriched supplement including zinc. J New Rem & Clin. 60:198–215. 2011.(In Japanese). | |
|
Nagao Y, Matsuoka H, Kawaguchi T and Sata M: Aminofeel® improves the sensitivity to taste in patients with HCV-infected liver disease. Med Sci Monit. 16:PI7–P12. 2010.PubMed/NCBI | |
|
Kawaguchi T, Yoshida T, Harada M, Hisamoto T, Nagao Y, Ide T, et al: Hepatitis C virus down-regulates insulin receptor substrates 1 and 2 through up-regulation of suppressor of cytokine signaling 3. Am J Pathol. 165:1499–1508. 2004. View Article : Google Scholar : PubMed/NCBI | |
|
Dupont WD and Plummer WD Jr: Power and sample size calculations. A review and computer program. Control Clin Trials. 11:116–128. 1990. View Article : Google Scholar : PubMed/NCBI | |
|
Suzuki K, Koizumi K, Ichimura H, Oka S, Takada H and Kuwayama H: Measurement of serum branched-chain amino acids to tyrosine ratio level is useful in a prediction of a change of serum albumin level in chronic liver disease. Hepatol Res. 38:267–272. 2008. View Article : Google Scholar | |
|
Riggio O, Merli M, Capocaccia L, Caschera M, Zullo A, Pinto G, et al: Zinc supplementation reduces blood ammonia and increases liver ornithine transcarbamylase activity in experimental cirrhosis. Hepatology. 16:785–789. 1992. View Article : Google Scholar : PubMed/NCBI | |
|
Chavez-Tapia NC, Cesar-Arce A, Barrientos-Gutierrez T, Villegas-Lopez FA, Mendez-Sanchez N and Uribe M: A systematic review and meta-analysis of the use of oral zinc in the treatment of hepatic encephalopathy. Nutr J. 12:742013. View Article : Google Scholar : PubMed/NCBI | |
|
Hagiwara A, Nishiyama M and Ishizaki S: Branched-chain amino acids prevent insulin-induced hepatic tumor cell proliferation by inducing apoptosis through mTORC1 and mTORC2-dependent mechanisms. J Cell Physiol. 227:2097–2105. 2012. View Article : Google Scholar | |
|
Nakao K and Ichikawa T: Recent topics on alpha-fetoprotein. Hepatol Res. 43:820–825. 2013. View Article : Google Scholar : PubMed/NCBI | |
|
Xie Z, Zhang H, Tsai W, Zhang Y, Du Y, Zhong J, et al: Zinc finger protein ZBTB20 is a key repressor of alpha-fetoprotein gene transcription in liver. Proc Natl Acad Sci USA. 105:10859–10864. 2008. View Article : Google Scholar : PubMed/NCBI | |
|
Nakanishi C, Doi H, Katsura K and Satomi S: Treatment with L-valine ameliorates liver fibrosis and restores thrombopoiesis in rats exposed to carbon tetrachloride. Tohoku J Exp Med. 221:151–159. 2010. View Article : Google Scholar : PubMed/NCBI | |
|
Zhang Y, Guo K, LeBlanc RE, Loh D, Schwartz GJ and Yu YH: Increasing dietary leucine intake reduces diet-induced obesity and improves glucose and cholesterol metabolism in mice via multimechanisms. Diabetes. 56:1647–1654. 2007. View Article : Google Scholar : PubMed/NCBI | |
|
Ikehara O, Kawasaki N, Maezono K, Komatsu M and Konishi A: Acute and chronic treatment of L-isoleucine ameliorates glucose metabolism in glucose-intolerant and diabetic mice. Biol Pharm Bull. 31:469–472. 2008. View Article : Google Scholar : PubMed/NCBI | |
|
Ishida H, Kato T, Takehana K, Tatsumi T, Hosui A, Nawa T, et al: Valine, the branched-chain amino acid, suppresses hepatitis C virus RNA replication but promotes infectious particle formation. Biochem Biophys Res Commun. 437:127–133. 2013. View Article : Google Scholar : PubMed/NCBI | |
|
Kugelmas M: Preliminary observation: oral zinc sulfate replacement is effective in treating muscle cramps in cirrhotic patients. J Am Coll Nutr. 19:13–15. 2000. View Article : Google Scholar : PubMed/NCBI | |
|
Sako K, Imamura Y, Nishimata H, Tahara K, Kubozono O and Tsubouchi H: Branched-chain amino acids supplements in the late evening decrease the frequency of muscle cramps with advanced hepatic cirrhosis. Hepatol Res. 26:327–329. 2003. View Article : Google Scholar : PubMed/NCBI |
