Plasma Branched-chain Amino Acids Research Articles

Altered Dairy Protein Intake Does Not Alter Circulatory Branched Chain Amino Acids in Healthy Adults: A Randomized Controlled Trial.

Dairy, as a major component of a high protein diet, is a critical dietary source of branched chain amino acids (BCAA), which are biomarkers of health and diseases. While BCAA are known to be key stimulators of protein synthesis, elevated circulatory BCAA is an independent risk factor for type 2 diabetes mellitus. This study examined the impact of altered dairy intake on plasma BCAA and their potential relationship to insulin sensitivity. Healthy adults (n = 102) were randomized to receive dietary advice to reduce, maintain, or increase habitual dairy intake for 1 month. Food intake was recorded with food frequency questionnaires. Self-reported protein intake from dairy was reported to be reduced (−14.6 ± 3.0 g/day), maintained (−4.0 ± 2.0 g/day) or increased (+13.8 ± 4.1 g/day) according to group allocation. No significant alterations in circulating free amino acids (AA), including BCAA, were measured. Insulin sensitivity, as assessed by homeostatic model assessment-insulin resistance (HOMA-IR), was also unaltered. A significant change in dairy protein intake showed no significant effect on fasting circulatory BCAA and insulin sensitivity in healthy populations.

Digestive Responses to Fortified Cow or Goat Dairy Drinks: A Randomised Controlled Trial.

Fortified milk drinks are predominantly manufactured from bovine (cow) sources. Alternative formulations include those prepared with hydrolysed bovine milk proteins or from alternate bovidae species, such as caprine (goat) milk. Currently, there is little data on protein digestive and metabolic responses following ingestion of fortified milk drinks. To examine the digestive and metabolic responses to commercially-available fortified milks, young adults (n = 15 males: 15 females), in a randomised sequence, ingested isonitrogenous quantities of whole cow-protein (WC), whole goat-protein (WG), or partially-hydrolysed whey cow-protein (HC), commercial fortified milks. Plasma amino acid (AA) and hormonal responses were measured at baseline and again at 5 h after ingestion. Paracetamol recovery, breath hydrogen, and subjective digestive responses were also measured. Postprandial plasma AA was similar between WC and WG, while AA appearance was suppressed with HC. Following HC, there was a negative incremental AUC in plasma branched-chain AAs. Further, HC had delayed gastric emptying, increased transit time, and led to exaggerated insulin and GLP-1 responses, in comparison to whole protein formulas. Overall, WC and WG had similar protein and digestive responses with no differences in digestive comfort. Contrastingly, HC led to delayed gastric emptying, attenuated AA appearance, and a heightened circulating insulin response.

GW29-e0692 Branched Chain Amino Acids Attenuates Hepatic Akt Signaling and Results in Severe Liver Metabolic Disorder in High Fat Diets Induced Obese Mice

With the prevalence of western diets (i.e. high fat plus high protein foods), the morbidity of T2DM and metabolic syndrome are increasingly high. Accumulating evidences point out that plasma branched chain amino acids (BCAA, the essential amino acids compromising 20% of the protein intake) level is

Mice deficient in the mitochondrial branched-chain aminotransferase (BCATm) respond with delayed tumour growth to a challenge with EL-4 lymphoma

BackgroundThe mitochondrial branched-chain aminotransferase (BCATm) is a recently discovered cancer marker with a poorly defined role in tumour progression.MethodsTo understand how a loss of function of BCATm affects cancer, the global knockout mouse BCATmKO was challenged with EL-4 lymphoma under different diet compositions with varying amounts of branched-chain amino acids (BCAAs). Next, the growth and metabolism of EL-4 cells were studied in the presence of different leucine concentrations in the growth medium.ResultsBCATmKO mice experienced delayed tumour growth when fed standard rodent chow or a normal BCAA diet. Tumour suppression correlated with 37.6- and 18.9-fold increases in plasma and tumour BCAAs, 37.5% and 30.4% decreases in tumour glutamine and alanine, and a 3.5-fold increase in the phosphorylation of tumour AMPK in BCATmKO mice on standard rodent chow. Similar results were obtained with a normal but not with a choice BCAA diet.ConclusionsGlobal deletion of BCATm caused a dramatic build-up of BCAAs, which could not be utilised for energy or amino acid synthesis, ultimately delaying the growth of lymphoma tumours. Furthermore, physiological, but not high, leucine concentrations promoted the growth of EL-4 cells. BCATm and BCAA metabolism were identified as attractive targets for anti-lymphoma therapy.

Timing of post-resistance exercise nutrient ingestion: effects on gastric emptying and glucose and amino acid responses in humans.

This study examined the effects of post-resistance exercise protein ingestion timing on the rate of gastric emptying (GE) and blood glucose (BG) and plasma branched-chain amino acid (BCAA) responses. In all, eleven healthy participants randomly ingested 400 ml of a nutrient-rich drink containing 12 g carbohydrates and 20 g protein at rest (Con), at 5 min (post-exercise (PE)-5) or at 30 min (PE-30) after a single bout of strenuous resistance exercises. The first and second sets comprised ten repetitions at 50 % of each participant's one-repetition maximum (1RM). The third, fourth and fifth sets comprised ten repetitions at 75 % of 1RM, and the sixth set involved repeated repetitions until exhaustion. Following ingestion of the nutrient-rich drink, we assessed the GE rate using 13C-sodium acetate breath test and evaluated two parameters according to the T max-calc (time when the recovery per hour is maximised), which is a standard analytical method, and T 1/2 (time when the total cumulative dose of [13CO2] reaches one-half). T max-calc and T 1/2 were slower for the PE-5 condition than for either the PE-30 or Con condition (T max-calc; Con: 53 (sd 7) min, PE-5: 83 (sd 16) min, PE-30: 62 (sd 9) min, T 1/2; Con: 91 (sd 7) min, PE-5: 113 (sd 21) min, PE-30: 91 (sd 11) min, P<0·05). BG and BCAA responses were also slower for the PE-5 condition than for either the PE-30 or Con condition. Ingesting nutrients immediately after strenuous resistance exercise acutely delayed GE, which affected BG and plasma BCAA levels in blood circulation.

Branched Chain Amino Acids in Metabolic Disease.

Elevations in circulating branched chain amino acids (BCAAs) have gained attention as potential contributors to the development of insulin resistance and diabetes. Epidemiological evidence strongly supports this conclusion. Suppression of BCAA catabolism in adipose and hepatic tissues appears to be the primary drivers of plasma BCAA elevations. BCAA catabolism may be shunted to skeletal muscle, where it indirectly leads to FA accumulation and insulin resistance, via a number of proposed mechanisms. BCAAs have an important role in the development of IR, but our understanding of how plasma BCAA elevations occur, and how these elevations lead to insulin resistance, is still limited.

Increased branched-chain amino acid levels are associated with long-term adverse cardiovascular events in patients with STEMI and acute heart failure

AimsThe long-term prognosis of ST-segment elevation myocardial infarction (STEMI) with acute heart failure (AHF) is poor. Identification of metabolic changes could provide understanding of the underlying pathological progress associated with adverse events in patients with STEMI and AHF. Therefore, the study aimed to identify new plasm metabolites associated with long-term adverse cardiovascular events in patients with STEMI and AHF. Materials and methodsMass spectrometry measurements of 26 amino acids were performed in 138 patients with STEMI and AHF. Endpoints were adverse cardiac events (composite of death and heart failure hospitalization). Survival analysis was performed to determine independent predictors of amino acids. Key findingsDuring a 3-year follow-up, there were 32 deaths and 21 hospitalizations for heart failure (HF). Multivariable Cox regression analysis showed that branched-chain amino acid (BCAA) levels were independent predictors for adverse cardiovascular events in patients with STEMI and AHF (adjusted HR: 2.67, p < 0.001). The prognostic value of BCAA was better than that of N-terminal pro-B-type natriuretic peptide (area under the curve: 0.77 vs. 0.72) and Kaplan–Meier curves for adverse cardiac events (log-rank: 14.91 vs. 10.05). The combination of BCAAs and NT-proBNP yielded a stronger predictive value (area under the curve: 0.81, log-rank: 27.14). Importantly, addition of BCAAs and NT-pro BNP to the Global Registry of Acute Coronary Events score increased the C-statistic from 0.707 to 0.813, with a net reclassification improvement of 0.714. SignificanceOur study shows that increased plasma BCAA levels are associated with long-term adverse cardiovascular events in patients with STEMI and AHF. These findings suggest that dysregulated BCAA metabolism pathways affect clinical outcome after STEMI with AHF.

Increased Levels of Branched-Chain Amino Acid Associated With Increased Risk of Pancreatic Cancer in a Prospective Case–Control Study of a Large Cohort

A marker is needed to identify individuals at risk for pancreatic cancer. Increases in branched-chain amino acids (BCAAs) have been associated with pancreatic cancer. We performed a prospective case-control study to study the association between plasma BCAA levels and risk of pancreatic cancer in a large cohort. We conducted a nested case-control study selected from 30,239 eligible participants 40-69 years old within the Japan Public Health Center-based prospective study. Over 16.4 years, 170 newly diagnosed pancreatic cancer cases were identified. Each case was matched to 2 controls by age, gender, geographic area, and fasting time at blood collection. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for pancreatic cancer were calculated using conditional logistic regression models with adjustment for potential confounding factors. Increased plasma BCAA levels at baseline were associated with an increased risk of pancreatic cancer. Compared with the lowest quartile of BCAA levels, the OR in the highest quartile was 2.43 (95% CI 1.21-4.90), and theOR per 1 SD increase in BCAA levels was 1.32 (95% CI 1.05-1.67). The association was especially strong for cases with blood samples collected at least 10 years before cancer diagnosis (OR per SD 1.60, 95% CI 1.10-2.32) compared with those detected less than 10 years before diagnosis (OR per SD 1.16, 95% CI 0.86-1.57). In an analysis of data fromthe Japan Public Health Center-based prospective study, we found an association between increased plasma BCAA level andincreased risk of pancreatic cancer-particularly when the increase in BCAAs was observed at least 10 years before diagnosis. These findings add to the growing body of evidence for the association between BCAA levels and pancreatic cancer risk.

Imbalanced dietary levels of branched-chain amino acids affect growth performance and amino acid utilization of juvenile red drum Sciaenops ocellatus

Imbalanced dietary levels of branched-chain amino acids (BCAAs) are known to produce antagonistic effects in pigs, rats and humans, affecting the concentration of BCAAs in plasma and ultimately depressing growth. In fish, antagonism involving BCAAs has not been fully characterized or understood. The objective of this study was to determine the effects of imbalanced dietary levels of BCAAs on growth performance and amino acid utilization of juvenile red drum. A control diet was prepared by combining lyophilized red drum muscle and crystalline amino acids, while keeping leucine (Leu), isoleucine (Ile) and valine (Val) at the previously quantified minimum dietary requirement levels for red drum. Six experimental diets were prepared by supplementing the control diet with (1) an excess of Leu, (2) an excess of Ile, (3) an excess of Val, (4) an excess of Leu and Ile, (5) an excess of Ile and Val, and (6) an excess of Leu and Val. Red drum juveniles were stocked in 38-L glass aquaria, and diets were fed to fish in triplicate aquaria, twice daily, for 45 d. At the end of the feeding trial, growth performance was evaluated and postprandial levels of BCAAs in plasma were analyzed. Growth performance of red drum was significantly depressed by an excess of dietary Leu, but not by an excess of Ile nor Val. The postprandial concentration of plasma Leu, Ile or Val was significantly higher in fish fed an excess of Leu, Ile or Val, respectively. Postprandial levels of BCAAs in plasma did not indicate that an excess of Leu blocked the intestinal absorption or promoted the catabolism of Ile and/or Val in red drum, as has been reported in other species. However, excess Leu did significantly reduce the postprandial concentration of α-ketoglutarate in plasma, possibly indicating a higher ratio of transamination due to the imbalanced postprandial concentration of BCAAs in plasma. In conclusion, an antagonistic effect due to excess dietary Leu was confirmed in juvenile red drum. This study represents a step forward in understanding the nature of the antagonistic effects among BCAAs in fish.

Branched-Chain Amino Acid (BCAA) Metabolism, Insulin Sensitivity (IS), and Liver Fat Response to Exercise Training in Sedentary Prediabetic and Normoglycemic Men

Studies suggest a role for BCAA in decreased IS and type 2 diabetes. Exercise improves IS, but the relationship with BCAA metabolism is unclear. We studied the effects of a 12 w exercise intervention on IS, liver fat and BCAA metabolism in prediabetic (n=13) and normoglycemic men (n=13). We estimated IS by hyperinsulinemic-euglycemic clamp, transcriptomics by mRNA-seq of skeletal muscle and adipose tissue biopsies, liver fat by MRI/MRS, and plasma (p)BCAA by HPLC, before and after the intervention. At baseline, liver fat and p-BCAA were higher, whereas IS and BCAA skeletal muscle and adipose tissue catabolism were lower in prediabetic vs. control men. Sum of pBCAA were elevated by 14% in prediabetic men and correlated negatively with IS (Figure A, p&amp;lt;0.05). Liver fat and adipose tissue BCAA catabolism correlated significantly to pBCAA levels. The exercise intervention increased IS by 29%, lowered liver fat by 25% and increased BCAA catabolism, whereas no significant change were observed in mean p-BCAA levels and changes did not correlate to changes in IS (Figure B). In conclusion, exercise intervention did not alter the mean pBCAA, despite significantly improved IS. We suggest that elevated pBCAA levels may not play a direct role causing insulin resistance, but rather is a consequence of accompanying alterations in liver, skeletal muscle and adipose tissue. Disclosure S. Lee: None. H.L. Gulseth: Advisory Panel; Self; Novo Nordisk A/S. Consultant; Self; Novo Nordisk A/S, Sanofi, Merck &amp; Co., Inc., AstraZeneca. H. Refsum: None. T.M. Langleite: None. T. Holen: None. J. Jensen: None. C.A. Drevon: None. K.I. Birkeland: Research Support; Self; AstraZeneca, Novo Nordisk A/S, Eli Lilly and Company, Sanofi, Boehringer Ingelheim GmbH, Merck Sharp &amp; Dohme Corp..

Whey Protein Augments Leucinemia and Postexercise p70S6K1 Activity Compared With a Hydrolyzed Collagen Blend When in Recovery From Training With Low Carbohydrate Availability.

We examined the effects of whey versus collagen protein on skeletal muscle cell signaling responses associated with mitochondrial biogenesis and protein synthesis in recovery from an acute training session completed with low carbohydrate availability. In a repeated-measures design (after adhering to a 36-hr exercise-dietary intervention to standardize preexercise muscle glycogen), eight males completed a 75-min nonexhaustive cycling protocol and consumed 22g of a hydrolyzed collagen blend (COLLAGEN) or whey (WHEY) protein 45min prior to exercise, 22g during exercise, and 22g immediately postexercise. Exercise decreased (p < .05) muscle glycogen content by comparable levels from pre- to postexercise in both trials (≈300-150mmol/kg·dry weight). WHEY protein induced greater increases in plasma branched chain amino acids (p = .03) and leucine (p = .02) than COLLAGEN. Exercise induced (p < .05) similar increases in PGC-1α (fivefold) mRNA at 1.5hr postexercise between conditions, although no effect of exercise (p > .05) was observed for p53, Parkin, and Beclin1 mRNA. Exercise suppressed (p < .05) p70S6K1 activity in both conditions immediately postexercise (≈25fmol·min-1·mg-1). Postexercise feeding increased p70S6K1 activity at 1.5hr postexercise (p < .05), the magnitude of which was greater (p < .05) in WHEY (180 ± 105fmol·min-1·mg-1) versus COLLAGEN (73 ± 42fmol·min-1·mg-1). We conclude that protein composition does not modulate markers of mitochondrial biogenesis when in recovery from a training session deliberately completed with low carbohydrate availability. By contrast, whey protein augments postexercise p70S6K activity compared with hydrolyzed collagen, as likely mediated via increased leucine availability.

Dietary Pattern and Plasma BCAA-Variations in Healthy Men and Women-Results from the KarMeN Study.

Branched-chain amino acids (BCAA) in plasma are discussed as risk factors for the onset of several diseases. Information about the contribution of the overall diet to plasma BCAA concentrations is controversial. Our objective was to investigate which dietary pattern is associated with plasma BCAA concentrations and whether other additional nutrients besides BCAA further characterize this dietary pattern. Based on the cross-sectional KarMeN study, fasting plasma amino acid (AA) concentrations, as well as current and habitual dietary intake were assessed in 298 healthy individuals. Using reduced rank regression, we derived a habitual dietary pattern that explained 32.5% of plasma BCAA variation. This pattern was high in meat, sausages, sauces, eggs, and ice cream but low in nuts, cereals, mushrooms, and pulses. The age, sex, and energy intake adjusted dietary pattern score was associated with an increase in animal-based protein together with a decrease in plant-based protein, dietary fiber, and an unfavorable fatty acid composition. Besides BCAA, alanine, lysine and the aromatic AA were positively associated with the dietary pattern score as well. All of these factors were reported to be associated with risk of type 2 diabetes and cardiovascular diseases before. Our data suggest that rather than the dietary intake of BCAA, the overall dietary pattern that contributes to high BCAA plasma concentrations may modulate chronic diseases risk.

Improvement in insulin-mediated suppression of branched-chain amino acid flux is responsible for the post-bariatric surgery decrease in plasma branched-chain amino acid levels

Improvement in insulin-mediated suppression of branched-chain amino acid flux is responsible for the post-bariatric surgery decrease in plasma branched-chain amino acid levels

Short- and long-term effects of leucine and branched-chain amino acid supplementation of a protein- and energy-reduced diet on muscle protein metabolism in neonatal pigs

The objective of this study was to determine if enteral leucine or branched-chain amino acid (BCAA) supplementation increases muscle protein synthesis in neonates who consume less than their protein and energy requirements, and whether this increase is mediated via the upregulation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway or the decrease in muscle protein degradation signaling. Neonatal pigs were fed milk replacement diets containing reduced energy and protein (R), R supplemented with BCAA (RBCAA), R supplemented with leucine (RL), or complete protein and energy (CON) at 4-h intervals for 9 (n = 24) or 21 days (n = 22). On days 9 and 21, post-prandial plasma amino acids and insulin were measured at intervals for 4h; muscle protein synthesis rate and activation of mTOR-related proteins were determined at 120min post-feeding in muscle. For all parameters measured, the effects of diet were not different between day 9 or day 21. Compared to CON and R, plasma leucine and BCAA were higher (P ≤ 0.01) in RL- and RBCAA-fed pigs, respectively. Body weight gain, protein synthesis, and activation of S6 kinase (S6K1), 4E-binding protein (4EBP1), and eukaryotic initiation factor 4 complex (eIF4E·eIF4G) were decreased in RBCAA, RL, and R relative to CON (P < 0.01). RBCAA and RL upregulated (P ≤ 0.01) S6K1, 4EBP1, and eIF4E·eIF4G compared to R. In conclusion, when protein and energy are restricted, both leucine and BCAA supplementation increase mTOR activation, but do not enhance skeletal muscle protein synthesis and muscle growth in neonatal pigs.

Resistance Exercise and Low Dose Protein Ingestion Augments Anabolic Signaling Mechanisms In Older Women

Resistance exercise enhances skeletal muscle anabolic signaling responses to the ingestion of sub-optimal amounts of protein in young men. However, the effectiveness of resistance exercise to potentiate the phosphorylation of the mechanistic target of rapamycin (mTORC1) to the ingestion of minimal amount of protein in aging women has not been well characterized. PURPOSE: We compared the phosphorylated-state ofmTORC1 before and after ingestion of ~14 g whey protein or water at rest and after resistance exercise in middle-aged and older women. METHODS: 10 women (59±2 y; BMI: 25±1 kg/m2; LBM: 46±2 kg) performed a bout of unilateral leg extension exercise (3 sets × 12 repetitions at 60% estimated 1RM) prior to ingesting whey protein (0.3g/kg LBM; WHEY, n=5) or water (WATER n=5). Blood and skeletal muscle biopsies were used to measure plasma amino acids and insulin concentrations and phosphorylation of mTORC1 at Ser2448 at 2 and 4 h of the postprandial phase in both exercise (EX) and non-exercised (CON) legs. RESULTS: Plasma branched chain amino acid concentrations were increased from basal (2.5-fold) in WHEY (P<0.05), but not in WATER condition (P>0.05). Plasma insulin concentrations increased after WHEY (2.3±0.8 fold change from basal, P=0.02), but not after WATER ingestion (1.0 ± 0.1 fold-change, P=0.45). WHEY ingestion increased mTORC1 phosphorylation at 2 h (3.4±0.6 and 1.7±0.3 fold-change in EX and CON, respectively P<0.05). There were no changes in mTORC1 phosphorylation after WATER ingestion at any time point (P>0.05). CONCLUSION: Our data demonstrated that consuming a minimal amount of protein immediately after resistance exercise resulted in a greater, but transient, phosphorylation of anabolic signaling mechanisms involved in protein translation over that induced by feeding or resistance exercise alone.

Pioglitazone improves hepatic mitochondrial function in a mouse model of nonalcoholic steatohepatitis

Pioglitazone is effective in improving insulin resistance and liver histology in patients with nonalcoholic steatohepatitis (NASH). Because dysfunctional mitochondrial metabolism is a central feature of NASH, we hypothesized that an important target of pioglitazone would be alleviating mitochondrial oxidative dysfunction. To this end, we studied hepatic mitochondrial metabolism in mice fed high-fructose high-transfat diet (TFD) supplemented with pioglitazone for 20 wk, using nuclear magnetic resonance-based 13C isotopomer analysis. Pioglitazone improved whole body and adipose insulin sensitivity in TFD-fed mice. Furthermore, pioglitazone reduced intrahepatic triglyceride content and fed plasma ketones and hepatic TCA cycle flux, anaplerosis, and pyruvate cycling in mice with NASH. This was associated with a marked reduction in most intrahepatic diacylglycerol classes and, to a lesser extent, some ceramide species (C22:1, C23:0). Considering the cross-talk between mitochondrial function and branched-chain amino acid (BCAA) metabolism, pioglitazone's impact on plasma BCAA profile was determined in a cohort of human subjects. Pioglitazone improved the plasma BCAA concentration profile in patients with NASH. This appeared to be related to an improvement in BCAA degradation in multiple tissues. These results provide evidence that pioglitazone-induced changes in NASH are related to improvements in hepatic mitochondrial oxidative dysfunction and changes in whole body BCAA metabolism.

Plasma Amino Acid Concentrations Are Associated with Muscle Function in Older Japanese Women.

Although several previous studies have found benefits for amino acid supplementation in terms of muscle function, the role of plasma amino acid concentrations on sarcopenia are not well addressed yet. The aim of this study was to compare the amino acid concentrations at each stage of sarcopenia (normal, pre-sarcopenia, dynapenia, and sarcopenia) in community-dwelling older Japanese adults. Community-dwelling older Japanese women (n=232, 79.4±7.0 years) participated in this study. We measured plasma amino acid concentrations, 5-m walking speed, grip strength, and skeletal muscle mass using a bioelectrical impedance data acquisition system and compared them among participants at each stage of sarcopenia. The proportions of normal, pre-sarcopenia, dynapenia, and sarcopenia patients were 40.5% (n=94), 12.1% (n=28), 26.3% (n=61), and 21.1% (n=49), respectively. Significant differences were observed for concentrations of leucine, branched-chain amino acid (BCAAs), and essential amino acid (EAAs) among the four groups (p<0.05), and the dynapenia and sarcopenia groups showed significantly lower concentrations of leucine than the normal group (p<0.05). This study indicated a positive relationship between plasma leucine, BCAA and EAA concentrations and muscle function. A longitudinal study is needed to determine the causal relationship between leucine/BCAA concentrations and muscle function.

Maintenance of plasma branched-chain amino acid concentrations during glucose infusion directs essential amino acids to extra-mammary tissues in lactating dairy cows

The objectives of this study were to investigate the effects of branched-chain AA (BCAA) supplementation when glucose is infused postruminally into lactating dairy cows consuming a diet low in crude protein (CP) and to test the hypothesis that low BCAA concentrations are responsible for the poor stimulation of milk protein yield by glucose. Twelve early-lactation Holstein cows were randomly assigned to 15% and 12% CP diets in a switchback design of 6-wk periods. Cows consuming the 12% CP diet received 96-h continuous jugular infusions of saline and 1 kg/d of glucose with 0, 75, or 150 g/d of BCAA in a Latin square sequence of treatments. Compared with saline, glucose infusion did not affect dry matter intake but increased milk yield by 2.2 kg/d and milk protein and lactose yields by 63 and 151 g/d, respectively. Mammary plasma flow increased 36% during glucose infusion compared with saline infusion, possibly because of a 31% decrease in total acetate plus β-hydroxybutyrate concentrations. Circulating concentrations of total essential AA and BCAA decreased 19 and 31%, respectively, during infusion of glucose, yet net mammary uptakes of AA remained unchanged compared with saline infusion. The addition of 75 and 150 g/d of BCAA to glucose infusions increased arterial concentrations of BCAA to 106 and 149%, respectively, of the concentrations in saline-infused cows, but caused a decrease in concentrations of non-branched-chain essential AA in plasma, as well as their mammary uptakes and milk protein yields. Plasma urea concentration was not affected by BCAA infusion, indicating no change in catabolism of AA. The lack of mammary and catabolic effects leads us to suggest that BCAA exerted their effects on plasma concentrations of the other essential AA by stimulating utilization in skeletal muscle for protein accretion. Results indicate that the glucose effect on milk protein yield was not limited by low BCAA concentrations, and that a stimulation of extra-mammary use of non-branched-chain essential amino acids by BCAA led to a decrease in milk protein yield.

A novel NMR-based assay to measure circulating concentrations of branched-chain amino acids: Elevation in subjects with type 2 diabetes mellitus and association with carotid intima media thickness

ObjectivesPlasma branched-chain amino acid (BCAA) levels, measured on nuclear magnetic resonance (NMR) metabolomics research platforms or by mass spectrometry, have been shown to be associated with type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). We developed a new test for quantification of BCAA on a clinical NMR analyzer and used this test to determine the clinical correlates of BCAA in 2 independent cohorts. Design and methodsThe performance of the NMR-based BCAA assay was evaluated. A method comparison study was performed with mass spectrometry (LC-MS/MS). Plasma BCAA were measured in the Insulin Resistance Atherosclerosis Study (IRAS, n = 1209; 376 T2DM subjects) and in a Groningen cohort (n = 123; 67 T2DM subjects). In addition, carotid intima media thickness (cIMT) was measured successfully in 119 subjects from the Groningen cohort. ResultsNMR-based BCAA assay results were linear over a range of concentrations. Coefficients of variation for inter- and intra-assay precision ranged from 1.8–6.0, 1.7–5.4, 4.4–9.1, and 8.8–21.3%, for total BCAA, valine, leucine, and isoleucine, respectively. BCAA quantified from the same samples using NMR and LC-MS/MS were highly correlated (R2 = 0.97, 0.95 and 0.90 for valine, leucine and isoleucine). In both cohorts total and individual BCAA were elevated in T2DM (P = 0.01 to ≤0.001). Moreover, cIMT was associated with BCAA independent of age, sex, T2DM and metabolic syndrome (MetS) categorization or alternatively of individual MetS components. ConclusionsBCAA levels, measured by NMR in the clinical laboratory, are elevated in T2DM and may be associated with cIMT, a proxy of subclinical atherosclerosis.

Connection Between BMI-Related Plasma Metabolite Profile and Gut Microbiota.

Emerging evidence has related the gut microbiome and circulating metabolites to human obesity. Gut microbiota is responsible for several metabolic functions, and altered plasma metabolome might reflect differences in the gut microbiome. To identify a plasma metabolite profile associated with body mass index (BMI) in a general population and investigate whether such metabolite profile is associated with distinct composition of the gut microbiota. Targeted profiling of 48 plasma metabolites was performed in a population of 920 Swedish adults (mean age, 39 years; 53% women) from the ongoing Malmö Offspring Study using targeted liquid chromatography-mass spectrometry. Gut microbiota was analyzed by sequencing the 16S ribosomal RNA gene (V1-V3 region) in fecal samples of 674 study participants. BMI was associated with 19 metabolites (P < 0.001 for all), of which glutamate provided the strongest direct association (P = 5.2e-53). By orthogonal partial least squares regression, a metabolite principal component predictive of BMI was constructed (PCBMI). In addition to glutamate, PCBMI was dominated by branched-chain amino acids (BCAAs) and related metabolites. Four gut microbiota genera (Blautia, Dorea, Ruminococcus, and SHA-98) were associated with both BMI and PCBMI (P < 8.0e-4 for all). When simultaneously regressing PCBMI and metabolite-associated gut bacteria against BMI, only PCBMI remained statistically significant. We discovered associations between four gut microbiota genera (Blautia, Dorea, Ruminococcus, and SHA-98) and BMI-predictive plasma metabolites, including glutamate and BCAAs. Thus, these metabolites could be mediators between gut microbiota and obesity, pointing to potential future opportunities for targeting the gut microbiota in prevention of obesity.