Arginine Intake Research Articles

Expression of proliferation markers in colonic mucosa in normal volunteers with a high arginine-containing diet and effect of dietary grape ingestion.

431 Background: Resveratrol, which inhibits ODC and Wnt signaling, has colon cancer prevention activity in animal models. To assess the effects of a resveratrol-rich diet on the colon, 30 normal volunteers enrolled on a cancer prevention clinical trial (NCT00578396) involving the ingestion of 1/3, 2/3, or 1 pound of grapes per day for 14 days. Data analysis was stratified based on arginine intake because meat and dietary arginine have been linked to colon carcinogenesis. Methods: Patients were placed on a low-resveratrol diet 14 days prior to and during the grape ingestion period. Detailed dietary information and colonic biopsies were obtained before and after the grape intervention in a single-subject design. Tissue was processed for RNA for qRT- PCR analysis of genes implicated in colonic proliferation, Wnt signaling and colon carcinogenesis. The % of cells expressing Ki67 in the lower 1/3 of colonic crypts was determined by IHC. Results: Mean arginine consumption for the study population was 4.5 ± 2.27 gm/day. Participants with higher initial dietary arginine consumption (> 4.5gm) had higher levels of cyclinD1 (p = 0.022), c-myc (p = 0.0002), axin2 (p = 0.0065) and CD133 (p = 0.041) mRNA in the colonic mucosa than participants with lower initial arginine consumption. No differences in the % of base of the colonic crypt cells staining for Ki67 were seen. Grape ingestion led to a significant reduction in cyclinD1 expression in participants with higher initial arginine consumption (p = 0.0039), with levels falling to those seen in low arginine consumption participants. Conclusions: Normal volunteers with a high amount of daily arginine ingestion had elevated levels of markers indicative of cell proliferation (cyclinD1, c-myc), Wnt signaling (axin2), and colonic stem cells (CD133). Expression of each of these markers was reduced following grape ingestion, though only the reduction in cyclinD1 reached statistical significance. Significance: Dietary arginine adversely affects colonic mucosa and may predispose individuals to the development of colon cancer. The effects are reversed in part by a resveratrol-rich grape-containing diet. Clinical trial information: NCT00578396.

Enteral Arginine Partially Ameliorates Parenteral Nutrition–Induced Small Intestinal Atrophy and Stimulates Hepatic Protein Synthesis in Neonatal Piglets

Arginine is an indispensable amino acid in neonates; de novo synthesis of arginine occurs in the small intestine (SI) but is reduced during parenteral nutrition (PN), limiting the arginine available to the mucosa. We assessed the effects of route of intake and dietary concentration of arginine on protein synthesis, superior mesenteric artery (SMA) blood flow, and SI morphology. Piglets (n = 18, 14-17 days old) were given complete PN for 3 days to induce SI atrophy, then switched to 1 of 3 treatments: arginine-free PN plus an intragastric (IG) infusion of high arginine (1.6 g · kg(-1)· d(-1), IG-H Arg) or low arginine (0.6 g · kg(-1)· d(-1), IG-L Arg) or complete high-arginine PN (1.6 g · kg(-1)· d(-1), IV-H Arg). Enteral arginine, irrespective of amount provided, stimulated hepatic protein synthesis compared with intravenous delivery of arginine (P = .01). SMA blood flow declined for all groups following the initiation of PN. After 48 hours on the test diets, all groups reached low constant levels, but the IV-H group was significantly higher than both IG groups (P < .05). Despite greater blood flow, the SI morphological characteristics in IV-H Arg pigs were not significantly improved over the other groups. IV-H Arg pigs had higher plasma concentrations of indispensable amino acids (tyrosine, isoleucine, and valine) compared with IG-H Arg, despite identical amino acid intakes. Intravenous delivery of arginine sustained the best SMA blood flow, whereas even a moderate amount of enteral arginine stimulated liver protein synthesis and maintained SI growth, independent of blood flow.

Dietary amino acids and the risk of hypertension in a Dutch older population: the Rotterdam Study

Inverse associations between dietary protein and hypertension have been reported, which may be attributed to specific amino acids. We examined whether the intake of glutamic acid, arginine, cysteine, lysine, or tyrosine was associated with blood pressure (BP) levels (n = 3086) and incident hypertension (n = 1810) in the Rotterdam Study. We calculated BP levels in quartiles of amino acid intake as a percentage of total protein intake (% of protein) with adjustment for age, sex, BMI, smoking, alcohol intake, education, and dietary factors. Subsequently, we used Cox proportional models that included the same confounders to evaluate the associations between specific amino acid intake and hypertension incidence. Glutamic acid contributed most to protein intake (21% of protein), whereas lysine provided 7%, arginine 5%, tyrosine 4%, and cysteine 1.5%. A higher intake of tyrosine (∼0.3% of protein) was significantly related to a 2.4-mm Hg lower systolic BP (P-trend = 0.05) but not to diastolic BP (P = 0.35). The other amino acids were not significantly associated with BP levels in a cross-sectional analysis. During 6 y of follow-up (7292 person-years), 873 cases of hypertension developed. None of the amino acids were significantly associated with incident hypertension (HR: 0.81-1.18; P-trend > 0.2). Our data do not suggest a major role for glutamic acid, arginine, lysine, tyrosine, or cysteine intake (as % of protein intake) in determining population BP or risk of hypertension.

Combined Oral Arginine and Monosodium Glutamate Exposure Induces Adverse Response on the Prostate Function and Testis Histology of Rats

Aims: This study investigated the effect of exposure to arginine (ARG) and glutamate (GLU), or its variant, monosodium glutamate (MSG) on the prostate function and testis histology of rats. Study Design: Exposure to either ARG, GLU, monosodium glutamate (MSG), ARG plus GLU or ARG plus MSG was per oral for 4 consecutive weeks. On the last day of the experiment, rats were food-deprived for 15 h before collecting their blood and testis samples. Place and Duration of Study: Department of Biochemistry and Department of Veterinary Pathology, University of Nigeria Nsukka, Nigeria, between June 2005 and June 2006. Methodology: Total and prostatic acid phosphatase activities in serum were determined by the method of Walter and Schutt. Testis sections were stained and mounted using haematoxylin and eosin (H&amp;E), for histology. Results: On comparison with control, the results showed that ARG, GLU, or arginine together with monosodium glutamate (ARG+MSG) induced a significant (p&lt;0.05 and p&lt;0.01) elevation whereas, ARG+GLU caused a reduction (p&lt;0.05 and p&lt;0.01), in serum total acid phosphatase (TAP) and prostatic acid phosphatase (PAP) activities. MSG-induced reduction in TAP activity (20.76 ± 0.18 I.U/L), however, was not statistically significant (p&gt;0.05 and p&gt;0.01). Histological examination of the testis sections revealed varying degree of degeneration characterized by necrosis in ARG+GLU and ARG+MSG groups relative to control and ARG, GLU or MSG groups. Conclusion: Results may indicate variable treatment related adverse effect on the prostate function and the testis histology of the rats. The possible effect, however, appeared higher following concomitant exposure to ARG and MSG. Thus, caution should be exercised in the simultaneous ingestion of arginine and monosodium glutamate in animals. Further work however, is required to address some shortcomings (including small sample size) of this study to validate reliability.

Dietary arginine and linear growth: the Copenhagen School Child Intervention Study

The amino acid arginine is a well-known growth hormone (GH) stimulator and GH is an important modulator of linear growth. The aim of the present study was to investigate the effect of dietary arginine on growth velocity in children between 7 and 13 years of age. Data from the Copenhagen School Child Intervention Study during 2001-2 (baseline), and at 3-year and 7-year follow-up, were used. Arginine intake was estimated via a 7 d precoded food diary at baseline and 3-year follow-up. Data were analysed in a multilevel structure in which children were embedded within schools. Random intercept and slopes were defined to estimate the association between arginine intake and growth velocity, including the following covariates: sex; age; baseline height; energy intake; puberty stage at 7-year follow-up and intervention/control group. The association between arginine intake and growth velocity was significant for the third and fourth quintile of arginine intake (2.5-2.8 and 2.8-3.2 g/d, respectively) compared with the first quintile ( < 2.2 g/d) (P for trend = 0.04). Protein intake (excluding arginine) was significantly associated with growth velocity; however, the association was weaker than the association between arginine intake and growth velocity (P for trend = 0.14). The results of the present study suggest a dose-dependent physiological role of habitual protein intake, and specifically arginine intake, on linear growth in normally growing children. However, since the study was designed in healthy children, we cannot firmly conclude whether arginine supplementation represents a relevant clinical strategy. Further research is needed to investigate whether dietary arginine may represent a nutritional strategy potentially advantageous for the prevention and treatment of short stature.

Effects of a diabetes-specific enteral nutrition on nutritional and immune status of diabetic, obese, and endotoxemic rats

Obese and type 2 diabetic patients present metabolic disturbance-related alterations in nonspecific immunity, to which the decrease in their plasma arginine contributes. Although diabetes-specific formulas have been developed, they have never been tested in the context of an acute infectious situation as can be seen in intensive care unit patients. Our aim was to investigate the effects of a diabetes-specific diet enriched or not with arginine in a model of infectious stress in a diabetes and obesity situation. As a large intake of arginine may be deleterious, this amino acid was given in graded fashion. Randomized, controlled experimental study. University research laboratory. Zucker diabetic fatty rats. Gastrostomized Zucker diabetic fatty rats were submitted to intraperitoneal lipopolysaccharide administration and fed for 7 days with either a diabetes-specific enteral nutrition without (G group, n=7) or with graded arginine supply (1-5 g/kg/day) (GA group, n=7) or a standard enteral nutrition (HP group, n=10). Survival rate was better in G and GA groups than in the HP group. On day 7, plasma insulin to glucose ratio tended to be lower in the same G and GA groups. Macrophage tumor necrosis factor-α (G: 5.0±1.1 ng/2×10⁶ cells·hr⁻¹; GA: 3.7±0.8 ng/2×10⁶ cells·hr⁻¹; and HP: 1.7±0.6 ng/2×10⁶ cells·hr⁻¹; p<.05 G vs. HP) and nitric oxide (G: 4.5±1.1 ng/2×10⁶ cells·hr⁻¹; GA: 5.1±1.0 ng/2×10⁶ cells·hr⁻¹; and HP: 1.0±0.5 nmol/2×10⁶ cells·hr⁻¹; p<.05 G and GA vs. HP) productions were higher in the G and GA groups compared to the HP group. Macrophages from the G and GA groups exhibited increased arginine consumption. In diabetic obese and endotoxemic rats, a diabetes-specific formula leads to a lower mortality, a decreased insulin resistance, and an improvement in peritoneal macrophage function. Arginine supplementation has no additional effect. These data support the use of such disease-specific diets in critically ill diabetic and obese patients.

Complementary dietary treatment using lysine-free, arginine-fortified amino acid supplements in glutaric aciduria type I — A decade of experience

The cerebral formation and entrapment of neurotoxic dicarboxylic metabolites (glutaryl-CoA, glutaric and 3-hydroxyglutaric acid) are considered to be important pathomechanisms of striatal injury in glutaric aciduria type I (GA-I). The quantitatively most important precursor of these metabolites is lysine. Recommended therapeutic interventions aim to reduce lysine oxidation (low lysine diet, emergency treatment to minimize catabolism) and to enhance physiologic detoxification of glutaryl-CoA via formation of glutarylcarnitine (carnitine supplementation). It has been recently shown in Gcdh−/− mice that cerebral lysine influx and oxidation can be modulated by arginine which competes with lysine for transport at the blood–brain barrier and the inner mitochondrial membrane [Sauer et al., Brain 134 (2011) 157–170]. Furthermore, short-term outcome of 12 children receiving arginine-fortified diet showed very promising results [Strauss et al., Mol. Genet. Metab. 104 (2011) 93–106]. Since lysine-free, arginine-fortified amino acid supplements (AAS) are commercially available and used in Germany for more than a decade, we evaluated the effect of arginine supplementation in a cohort of 34 neonatally diagnosed GA-I patients (median age, 7.43years; cumulative follow-up period, 221.6patientyears) who received metabolic treatment according to a published guideline [Kölker et al., J. Inherit. Metab. Dis. 30 (2007) 5–22]. Patients used one of two AAS product lines during the first year of life, resulting in differences in arginine consumption [group 1 (Milupa Metabolics): mean=111mg arginine/kg; group 2 (Nutricia): mean=145mg arginine/kg; p<0.001]. However, in both groups the daily arginine intake was increased (mean, 137mg/kg body weight) and the dietary lysine-to-arginine ratio was decreased (mean, 0.7) compared to infants receiving human milk and other natural foods only. All other dietary parameters were in the same range. Despite significantly different arginine intake, the plasma lysine-to-arginine ratio did not differ in both groups. Frequency of dystonia was low (group 1: 12.5%; group 2: 8%) compared with patients not being treated according to the guideline, and gross motor development was similar in both groups. In conclusion, the development of complementary dietary strategies exploiting transport competition between lysine and arginine for treatment of GA-I seems promising. More work is required to understand neuroprotective mechanisms of arginine, to develop dietary recommendations for arginine and to evaluate the usefulness of plasma monitoring for lysine and arginine levels as predictors of cerebral lysine influx.

Effect of pre-exercise single dose arginine ingestion on plasma amino acid profile during exhaustive exercise in elite male wrestlers

Aim: The aim of this study was to investigate the possible effects of pre-exercise single dose arginine ingestion on plasma amino acid profile during incremental exercise to exhaustion. Methods: Ten volunteer elite male wrestlers (age: 24.7±3.8) participated in this study. Testretest protocol was done on the same subjects. Exercise protocol started at 90 watts on bicycle ergometry and the load was increased 30 watts in every 3 min till the exhaustion. Arginine (1.5gr/10 kg body weight) or placebo were given to the subjects after 12 h fasting (during the night) and venous blood samples were collected 1 h after the supplementation (right before exercise protocol) and right after the exercise protocol for both test and retest. Plasma amino acid profiles were determined by HPLC. Results: Preand post-exercise arginine, ornithine and citrulline concentrations were significantly higher in arginine vs. placebo trial (p<0.05). Glutamine, tyrosine, methionine, phenylalanine, isoleucine and leucine concentrations increased following exercise only in arginine trial (p<0.05). Citrulline and tryptophan levels decreased while alanine levels increased after exercise in both trials (p<0.05). There was an increase following exhaustive exercise in total branched chain amino acid concentrations in arginine trial (p<0.05) whereas there is no significant change in placebo trial. Total amino acid concentrations were increased with exercise in both trials but post-exercise concentrations was higher in arginine trial compared to placebo trial (p<0.05). Conclusion: Results suggest that pre-exercise arginine supplementation can promote an amino acid profile that could be favorable for performance; however, further investigation is necessary to determine the effect of arginine supplementation on athletic performance.

Arginine requirement and effect of arginine intake on immunity in largemouth bass, Micropterus salmoides

An 8‐week feeding test was conducted to quantify the dietary arginine requirement of juvenile largemouth bass (LMB) (25 ± 0.4 g). Six isonitrogenous and isolipidic (459 g crude protein and 122 g crude lipid kg−1 dry diet) diets were formulated to contain graded levels of arginine (17.0–30.1 g kg−1 dry diet). Zein‐coated crystalline amino acid mixtures were supplemented to simulate, except for arginine, the amino acid profile of the muscle protein of LMB. Each diet was randomly assigned to quadruplicate tanks of 35 fish reared in a flow‐through system. Fish were fed to apparent satiation twice daily. Weight gain (WG) was significantly affected by dietary arginine level. Nitrogen retention was significantly lower in fish fed D17.0. Arginine retention significantly decreased with dietary arginine increased. Threonine, leucine and lysine concentrations in whole body were significantly affected by dietary arginine level. Serum lysozyme activity, serum protein and respiratory burst of head kidney leucocytes were significantly affected, while complement activity (CH50) showed no difference among treatments. Based on broken‐line analysis for WG against dietary digestible arginine level, the arginine requirement of LMB was 19.1 g kg−1 of dry diet (41.6 g kg−1 of crude protein).

Safety, efficacy and physiological actions of a lysine-free, arginine-rich formula to treat glutaryl-CoA dehydrogenase deficiency: Focus on cerebral amino acid influx

Striatal degeneration from glutaryl-CoA dehydrogenase deficiency (glutaric aciduria type 1, GA1) is associated with cerebral formation and entrapment of glutaryl-CoA and its derivatives that depend on cerebral lysine influx. In 2006 we designed a lysine-free study formula enriched with arginine to selectively block lysine transport across cerebral endothelia and thereby limit glutaryl-CoA production by brain. Between 2006 and present, we treated twelve consecutive children with study formula (LYSx group) while holding all other treatment practices constant. Clinical and biochemical outcomes were compared to 25 GA1 patients (PROx group) treated between 1995 and 2005 with natural protein restriction (dietary lysine/arginine ratio of 1.7±0.3mg:mg). We used published kinetic parameters of the y+and LAT1 blood–brain barrier transporters to model the influx of amino acids into the brain. Arginine fortification to achieve a mean dietary lysine/arginine ratio of 0.7±0.2mg:mg was neuroprotective. All 12 LYSx patients are physically and neurologically healthy after 28 aggregate patient-years of follow up (current ages 28±21months) and there were no adverse events related to formula use. This represents a 36% reduction of neurological risk (95% confidence interval 14–52%, p=0.018) that we can directly attribute to altered amino acid intake. During the first year of life, 20% lower lysine intake and two-fold higher arginine intake by LYSx patients were associated with 50% lower plasma lysine, 3-fold lower plasma lysine/arginine concentration ratio, 42% lower mean calculated cerebral lysine influx, 54% higher calculated cerebral arginine influx, 15–26% higher calculated cerebral influx of several anaplerotic precursors (isoleucine, threonine, methionine, and leucine), 50% less 3-hydroxyglutarate excretion, and a 3-fold lower hospitalization rate (0.8 versus 2.3 hospitalizations per patient per year). The relationship between arginine fortification and plasma lysine indicates that transport competition exists at both cerebrovascular and gastrointestinal barriers, suggesting their co-administration is key to efficacy. Monitoring the ratio between lysine and arginine in diet and plasma may prove a useful strategy for treating children with GA1.

Nutritional status of subjects with dominant plant food consumption

In three groups of apparently healthy subjects – vegetarians (plant food, dairy products, eggs), semi-vegetarians (as vegetarians with addition of white meat consumption) and non-vegetarians (control group on traditional mixed diet) were analyzed the dietary questionnaires of consumption frequency and measured the values of lipid profile, insulin resistance, homocysteine with determinants (vitamins B6, B9, B12) and plasma antioxidative vitamins (C,E, beta-carotene). Vegetarians and semi-vegetarians consumed the significantly reduced amount of cholesterol, saturated fatty acids, methionine, lysine, vitamin B12 and on the other hand, they have the significantly higher daily intake of polyunsaturated fatty acids, linoleic acid, alpha-linolenic acid, fiber, plant proteins, arginine, glycine, serine, alanine, folic acid (vitamin B9), vitamin B6, vitamins C,E and beta-carotene. Alternative nutrition groups vs. non-vegetarians have the significantly reduced concentrations of total and LDL-cholesterol, triacylglycerols, insulin as well as values of atherogenic index and insulin resistance. The vegetarian (but not semi-vegetarian) value of homocysteine is significantly increased as a consequence of the significantly reduced and low concentration of vitamin B12. Other two determinants of homocysteine degradation were significantly increased in serum of alternative nutrition groups. The both vegetarian groups have the significantly higher plasma concentrations of antioxidative vitamins and these values are in range of effective free radical disease reduction. The results of favourable values of cardiovascular risk markers and antioxidants document a beneficial effect of vegetarian nutrition in prevention of degenerative age-related diseases.

A phase IIa clinical biomarker trial of aspirin and dietary arginine restriction in colorectal cancer patients.

TPS132 Background: Colorectal cancer (CRC) patients are at high risk for recurrence and for secondary CRC development. Our preliminary findings provide a rationale for reducing tissue polyamines as tertiary chemoprevention in local and locally-advanced CRC patients. We will attempt to demonstrate rectal tissue putrescine reduction in stage I-III, optimally-treated CRC patients after treatment with dietary arginine restriction + daily oral aspirin in a phase IIa clinical biomarker trial. Methods: 24 participants will be treated with aspirin and an individualized dietary regimen to reduce arginine intake by >30% during the 12-week intervention. Sample size calculations were based on the Binomial test for a single proportion, to yield 80% Power. Six patients will receive psychosocial telephone counseling (PTC). Endoscopy with serial biopsies, phlebotomy, and urine collection will be performed pre- and post-intervention to assess potential biomarkers. The primary endpoint is a > 50% decrease in rectal tissue putrescine levels from baseline, as a measure of polyamine reduction in the target tissue of CRC patients. Secondary aims include: to demonstrate significant alterations in secondary endpoint biomarkers relevant to polyamine metabolism in CRC patients, including rectal mucosa Odc1 and Ssat expression and urinary polyamine metabolites; to determine this intervention’s side-effect profile in a population of optimally-treated CRC patients; to determine the efficacy of accrual to this novel type of clinical trial involving dietary intervention and oral aspirin therapy among a group of potentially cured cancer patients for whom there is currently no recommended further therapy; to assess feasibility of PTC and collect pilot data regarding the influence of PTC on compliance with the dietary prescription and compliance with aspirin, and if PTC further influences healthy exercise, reduced fatigue and improved quality of life when compared to the non-counseled cohort. Hypothesis: Among optimally-treated stage I-III CRC patients, a 12-week intervention of daily aspirin and a low-meat, arginine-restricted diet will favorably alter polyamine-related tissue, serum, and urinary biomarker levels.

Effect of Oral Arginine Supplementation on Exhaled Nitric Oxide Concentration in Sickle Cell Anemia and Acute Chest Syndrome

Decreased exhaled nitric oxide levels (FE(NO)) have been described in patients with sickle cell disease (SCD) and a history of acute chest syndrome (ACS) when compared with non-ACS controls. Oral arginine supplementation has been shown to increase FE(NO) in healthy participants, but its effect in SCD patients is not known. To determine the effect of oral arginine intake on FENO in sickle cell patients with and without history of ACS, and in healthy controls. No differences in the FE(NO) increase were seen in SCD patients with a history of ACS (ACS+) compared with healthy controls (HC) and SCD patients without history of ACS (ACS-). ACS+ (n=6), ACS- (n=9), and HC (n=7) patients were studied. At baseline, and after the administration of escalating doses of oral L-arginine (0.1, 0.2, and 0.4 g/kg), serial measurements were made of the following: FE(NO), plasma concentrations of arginine, ornithine, citrulline, aspartate, glutamate, arginine/ornithine ratio, nitrite, nitrate, heart rate (HR), respiratory rate (RR), blood pressure (BP), oxygen saturation (SpO2), forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC). At baseline, FE(NO) did not differ among the groups. ACS- and ACS+ groups were deficient in arginine, and had decreased FEV1, FVC, and SaO2 when compared with HC patients. After arginine supplementation, FE(NO), arginine, ornithine, citrulline, nitrite, and the arginine/ornithine ratio increased similarly in all groups. Changes from baseline for HR, BP, SpO2, RR, FEV1, and FVC were minimal and similar in all groups. In contrast to our earlier study, ACS+ patients had similar FE(NO) values when compared with ACS- and HC patients. All SCD patients were arginine deficient at baseline and showed impairment in respiratory physiology when compared with HC patients. After arginine supplementation, FE(NO) concentration increased in all groups to a similar degree, and lung function and physiologic parameters were minimally affected. The physiologic significance of alterations in FE(NO) in SCD patients and its relationship to ACS predilection requires further delineation.

Dietary Supplementation of L-Arginine and Conjugated Linoleic Acid Reduces Retroperitoneal Fat Mass and Increases Lean Body Mass in Rats ,

We hypothesized that L-arginine and conjugated linoleic acid (CLA) would have additive effects in decreasing adiposity. Sprague Dawley rats were assigned to the following dietary groups (n = 6/group; 5 wk total): 1) control (2.55% L-alanine plus 1.5% canola oil); 2) arginine (1.25% L-arginine plus 1.5% canola oil); 3) CLA (2.55% L-alanine plus 1.5% CLA); and 4) arginine plus CLA (1.25% L-arginine plus 1.5% CLA). Supplemental amino acids were provided in drinking water and CLA was incorporated into the food pellets. Daily weight gain, food intake, arginine intake, and final body and eviscerated body weights were greater in rats fed supplemental CLA then in rats fed canola oil. The retroperitoneal adipose tissue:body weight ratio was less in rats fed supplemental CLA than in rats fed canola oil, but epididymal adipose tissue, liver, and soleus and extensor digitorum longus muscle weights were unaffected by arginine or CLA. CLA decreased epididymal adipose tissue concentrations of palmitoleic, oleic, and cis-vaccenic acid. CLA and arginine increased palmitate oxidation to CO2 in epididymal adipose tissue in vitro relative to control rats. Glucose and palmitate incorporation into total lipids in epididymal adipose tissue was lower in rats fed supplemental arginine than in alanine-fed rats. Arginine increased plasma glycerol relative to alanine-fed rats and CLA and arginine independently decreased most serum essential amino acids and alanine, glutamate, glutamine, and ornithine. We conclude that CLA and arginine modulated adipose tissue metabolism by separate, but not additive, effects. Also, CLA and arginine may have depressed muscle protein turnover.

Dietary Fiber and Other Alternative Therapies and Irritable Bowel Syndrome

Dietary fiber has demonstrated benefits in health maintenance, disease prevention, and in medical nutrition therapy. Dietary fiber is consumed in foods, dietary supplements, and in over-the-counter drugs as an aid to laxation. In developed countries, usual intake of dietary fiber is only about half of recommended levels. Irritable bowel syndrome (IBS) is the world's most common gastrointestinal functional disorder and greatly limits patients' quality of life. The pathological mechanisms of IBS are unknown, but consumption of dietary fiber may have therapeutic benefits for patients with the syndrome. Some studies find that soluble fibers are more successful than insoluble fibers in the management of IBS. Other fibers shown to have a positive effect on irritable bowel symptoms include wheat dextrin, partially hydrolyzed guar gum, and psyllium. Little data are available on probiotics and prebiotics and IBS. Other alternative therapies including peppermint oil, zinc, arginine, and restricted fructose intakes have been promoted for IBS. Dietary management of IBS must be individualized as symptoms of IBS vary widely.

Association between dietary protein and change in body composition among children (EYHS)

Growth hormone (GH) affects body composition by a relatively reduced fat mass and increased fat free mass. The intake of protein as well as the specific amino acids arginine and lysine potently stimulate GH secretion. This study investigated associations between intakes of protein, arginine, lysine and subsequent 6-year change in body composition among 8-10-year-old children. Data of 364 children were collected from Odense, Denmark, during 1997-1998 and 6-year later as part of the European Youth Heart Study. Body mass index among children was subdivided by fat free mass index (FFMI) and fat mass index (FMI), based on skinfold measurements. Dietary intake was estimated via 24h recall. Associations between intakes of protein as well as arginine, lysine and change in FFMI and FMI were analysed by multiple linear regressions, adjusted for social economic status, puberty stage and physical activity level. Among lean girls inverse associations were found between protein as well as arginine and lysine intake and change in fat mass index (beta=-1.12+/-0.56, p=0.03, beta=-1.10+/-0.53, p=0.04, beta=-1.13+/-0.51, p=0.03 respectively). Furthermore among girls with a body mass index in the 5th quintile, protein intake was associated with DeltaFFMI (p=0.04), and more specific when LYS intake was high, ARG intake was associated with DeltaFFMI (p=0.04). Among girls high protein intakes may decrease body fat gain and increase fat free mass gain, depending on the available amounts and combinations of arginine and lysine.

Prevention of Amino Acid Conversion in SILAC Experiments with Embryonic Stem Cells

Recent studies using stable isotope labeling with amino acids in culture (SILAC) in quantitative proteomics have made mention of the problematic conversion of isotope-coded arginine to proline in cells. The resulting converted proline peptide divides the heavy peptide ion signal causing inaccuracy when compared with the light peptide ion signal. This is of particular concern as it can effect up to half of all peptides in a proteomic experiment. Strategies to both compensate for and limit the inadvertent conversion have been demonstrated, but none have been shown to prevent it. Additionally, these methods combined with SILAC labeling in general have proven problematic in their large scale application to sensitive cell types including embryonic stem cells (ESCs) from the mouse and human. Here, we show that by providing as little as 200 mg/liter L-proline in SILAC media, the conversion of arginine to proline can be rendered completely undetectable. At the same time, there was no compromise in labeling with isotope-coded arginine, indicating there is no observable back conversion from the proline supplement. As a result, when supplemented with proline, correct interpretation of "light" and "heavy" peptide ratios could be achieved even in the worst cases of conversion. By extending these principles to ESC culture protocols and reagents we were able to routinely SILAC label both mouse and human ESCs in the absence of feeder cells and without compromising the pluripotent phenotype. This study provides the simplest protocol to prevent proline artifacts in SILAC labeling experiments with arginine. Moreover, it presents a robust, feeder cell-free, protocol for performing SILAC experiments on ESCs from both the mouse and the human.

Association between dietary arginine and lysine intake and 6 years change in body composition among 9-year-old children (EYHS)

Association between dietary arginine and lysine intake and 6 years change in body composition among 9-year-old children (EYHS)

Effect of strength training session on plasma amino acid concentration following oral ingestion of arginine or taurine in men

This study examined the acute effects of a one-hour hypertrophic strength training session (STS) on plasma amino acid concentration following oral ingestion of arginine or taurine in nine physically active men participating in a double-blind and randomised experiment. The subjects took placebo, arginine or taurine capsules (50 mg/kg) in either rest (REST) or STS condition. Blood samples were taken before and at 30, 60, 90, and 120 min after the beginning of the treatment and assayed for plasma amino acids with HPLC. There was a significant interaction effect with STS and sample time for both arginine and taurine in the raw data (p < 0.05). The modelled polynomial data for the arginine treatment showed that the peak concentration of arginine occurred at 69 min at rest and at 104 min in STS, and for the taurine treatment, the peak concentration of taurine occurred at 89 min at rest and at 112 min in STS. In conclusion, one hour of hypertrophic STS slows the increase in the peak concentration of plasma arginine and taurine after oral ingestion of the respective amino acids.

Variation in L-arginine intake follow demographics and lifestyle factors that may impact cardiovascular disease risk.

Little is known regarding the patterns of dietary intake of the amino acid L-arginine in the general population and, particularly, whether intake varies according to race or the presence of cardiovascular risk factors. This study is an analysis of adults 18 years and older who participated in the Third National Health and Nutrition Examination Survey, a national public-use nutrition survey of noninstitutionalized persons. Mean arginine intake for the US adult population was 4.40 g/d, with 25% of people consuming less than 2.6 g/d. Minorities, obese individuals, and people with diabetes consumed more arginine per 4.19 kJ than people without those characteristics. Whites had consistently lower intake than African Americans and Hispanics. Smokers had lower intake than nonsmokers. After adjustment for demographic factors and energy intake, women and smokers remained more likely to be in the lowest quartile of arginine consumption. Hypertension status was not significantly related to arginine consumption. In conclusion, L-arginine intake varies according to demographic and cardiovascular risk factors in the population. These results may have implications for cardiovascular risk.