Casein Protein Processing Strongly Modulates Post-Prandial Plasma Amino Acid Responses In Vivo in Humans.

Micellar casein is characterized as a slowly digestible protein source, and its structure can be modulated by various food processing techniques to modify its functional properties. However, little is known about the impact of such modifications on casein protein digestion and amino acid absorption kinetics and the subsequent post-prandial plasma amino acid responses. In the present study, we determined post-prandial aminoacidemia following ingestion of isonitrogenous amounts of casein protein (40 g) provided as micellar casein (Mi-CAS), calcium caseinate (Ca-CAS), or cross-linked sodium caseinate (XL-CAS). Fifteen healthy, young men (age: 26 ± 4 years, BMI: 23 ± 1 kg·m-2) participated in this randomized cross-over study and ingested 40 g Mi-Cas, Ca-CAS, and XL-CAS protein, with a ~1 week washout between treatments. On each trial day, arterialized blood samples were collected at regular intervals during a 6 h post-prandial period to assess plasma amino acid concentrations using ultra-performance liquid chromatography. Plasma amino acid concentrations were higher following the ingestion of XL-CAS when compared to Mi-CAS and Ca-CAS from t = 15 to 90 min (all p < 0.05). Plasma amino acid concentrations were higher following ingestion of Mi-CAS compared to Ca-CAS from t = 30 to 45 min (both p < 0.05). Plasma total amino acids iAUC were higher following the ingestion of XL-CAS when compared to Ca-CAS (294 ± 63 vs. 260 ± 75 mmol·L-1, p = 0.006), with intermediate values following Mi-CAS ingestion (270 ± 63 mmol·L-1, p > 0.05). In conclusion, cross-linked sodium caseinate is more rapidly digested when compared to micellar casein and calcium caseinate. Protein processing can strongly modulate the post-prandial rise in plasma amino acid bioavailability in vivo in humans.

[Dietary control of metabolic acidosis in chronic kidney disease]. / Contrôle diététique de l'acidose métabolique chez le patient insuffisant rénal chronique.

Metabolic acidosis is a frequent complication of chronic kidney disease. Although it is known to appear at advanced stages, many studies suggest a state of "global protonic retention" starting at early stages of the disease, responsible of tissue damage, particularly musculoskeletal, alteration of protidic metabolism and endocrine disorders, promoting malnutrition and chronic inflammation, and finally increasing mortality. The majority of international recommandations suggest of supplementation by alkali, most of the time by sodium bicarbonate, to struggle against this complication. An interesting alternative to correct acidosis would consist on the modulation of the endogenous production of acid by playing with the alimentary incomes. In fact, it has been demonstrated that some different types of food produce or consume protons during their metabolism. Low protein diet and rich fresh fruits and vegetables diet would manage to correct at least as well as the supplementation by sodium bicarbonate the metabolic acidosis, and to struggle against its complications, noteworthy by slowing the decline of glomerular filtration rate by limiting the toxic adaptative fibrotic mechanisms, demonstrated by the decrease of urinary tubulo-interstitial suffering markers. Of the condition of being well led, those diets do not seem to expose patients to an over-risk of malnutrition or hyperkaliemia. They therefore appear to be an attractive alternative, efficiency and safe, to fight against chronic kidney disease metabolic acidosis and its complications.

Bioavailability and Safety of Nutrients from the Microalgae Chlorella vulgaris, Nannochloropsis oceanica and Phaeodactylum tricornutum in C57BL/6 Mice.

Microalgae are rich in macronutrients and therefore, they have been proposed as a potential future food source preserving natural resources. Here, we studied safety and bioavailability of algae nutrients in mice. Three microalgae species, Chlorella vulgaris, Nannochloropsis oceanica and Phaeodactylum tricornutum, were studied after ball mill disruption at different doses (5%, 15% and 25% dry weight) for 14 days. In response to all three algae diets, we observed a weight gain similar or superior to that in response to the control diet. No substantial differences in organ weights nor gut length occurred. Protein bioavailability from the algae diets did not differ from the control diet ranging from 58% to 77% apparent biological value. Fat absorption was lower for microalgae compared to soy oil in control diets, albeit still substantial. High liver eicosapentaenoic acid levels were measured following feeding with N. oceanica, the algae richest in omega-3 fatty acids. Neither histological nor serum analyses revealed any heart, kidney or liver toxicity induced by any of the algae diets. Algae-rich diets were thus well accepted, well tolerated and suitable for the maintenance of body weight and normal organ function. No toxicological effects were observed.

Pea Ferritin Stability under Gastric pH Conditions Determines the Mechanism of Iron Uptake in Caco-2 Cells.

Background: Iron deficiency is an enduring global health problem that requires new remedial approaches. Iron absorption from soybean-derived ferritin, an ∼550-kDa iron storage protein, is comparable to bioavailable ferrous sulfate (FeSO4). However, the absorption of ferritin is reported to involve an endocytic mechanism, independent of divalent metal ion transporter 1 (DMT-1), the transporter for nonheme iron. Objective: Our overall aim was to examine the potential of purified ferritin from peas (Pisum sativum) as a food supplement by measuring its stability under gastric pH treatment and the mechanisms of iron uptake into Caco-2 cells. Methods: Caco-2 cells were treated with native or gastric pH-treated pea ferritin in combination with dietary modulators of nonheme iron uptake, small interfering RNA targeting DMT-1, or chemical inhibitors of endocytosis. Cellular ferritin formation, a surrogate measure of iron uptake, and internalization of pea ferritin with the use of specific antibodies were measured. The production of reactive oxygen species (ROS) in response to equimolar concentrations of native pea ferritin and FeSO4 was also compared. Results: Pea ferritin exposed to gastric pH treatment was degraded, and the released iron was transported into Caco-2 cells by DMT-1. Inhibitors of DMT-1 and nonheme iron absorption reduced iron uptake by 26-40%. Conversely, in the absence of gastric pH treatment, the iron uptake of native pea ferritin was unaffected by inhibitors of nonheme iron absorption, and the protein was observed to be internalized in Caco-2 cells. Chlorpromazine (clathrin-mediated endocytosis inhibitor) reduced the native pea ferritin content within cells by ∼30%, which confirmed that the native pea ferritin was transported into cells via a clathrin-mediated endocytic pathway. In addition, 60% less ROS production resulted from native pea ferritin in comparison to FeSO4. Conclusion: With consideration that nonheme dietary inhibitors display no effect on iron uptake and the low oxidative potential relative to FeSO4, intact pea ferritin appears to be a promising iron supplement.

Polyphenols and Their Interactions With Other Dietary Compounds: Implications for Human Health.

Regular and optimal intake of polyphenols associates with numerous health-promoting effects. Bioavailability and activity of polyphenols depend on foods' structure and interactions with other food constituents, especially proteins, lipids, and carbohydrates. Polyphenols-proteins interactions can result in various biological effects, such as sense of astringency. So far, polyphenols interactions with food lipids have not been of special importance, except in case of plant oils. Polyphenols-carbohydrates interactions can influence the organoleptic properties, while interactions with dietary fibers are particularly significant. Polyphenols can decrease the synthesis of fats and fatty acids in the liver, or delay their absorption in intestines. Also, polyphenols can slow down digestion of carbohydrates, through the inhibition of digestive enzymes or modulation of glucose uptake. Both animal and plant proteins have low impact on the bioavailability of polyphenols, but some in vitro studies reported that milk proteins could enhance intestinal absorption of polyphenols from tea. Dietary fats may alter the passage of polyphenols through gastrointestinal tract and impact absorption of more hydrophobic polyphenols in particular. While some studies reported that associations with carbohydrates could decrease bioavailability of polyphenols, the others showed the opposite effects. Macronutrients can be used for encapsulation of polyphenols, which can increase their bioavailability and ensure controlled and targeted release. Polyphenols' interactions in the body include their incorporation in cell membranes which causes changes in fatty acid profile and impacts membrane-bound transporters and enzymes. Finally, gut microbiota plays essential role in metabolism of both polyphenols and macronutrients and thus can have great impact on their interactions.

Efectos en el rendimiento físico de la ingesta de suplementos con carbohidratos y proteína durante el ejercicio: revisión sistemática / Effects of ingesting carbohydrate-protein supplements during exercise on endurance performance: a systematic review

Introducción: las bebidas deportivas ayudan a mejorar el rendimiento físico de forma significativa debido a su aporte de carbohidratos, electrolitos y agua. Sin embargo, en las últimas décadas se ha encontrado que ingerir una bebida deportiva con proteína durante el ejercicio mejora el rendimiento físico, produce menores pérdidas de peso corporal inducidas por la deshidratación y ayuda a disminuir el daño muscular post ejercicio en comparación con una bebida únicamente con carbohidratos y electrolitos. Objetivo: analizar los principales estudios sobre la efectividad de la ingesta de un suplemento con carbohidratos, proteína y electrolitos durante el ejercicio. Método: se realizó una búsqueda automatizada en Google académico, EBSCO, PubMEd y Scopus, utilizando las palabras clave: Carbohydrate-protein and performance y Added protein and sports drink. Se evaluó la calidad metodológica de los ensayos y se tomó en cuenta que la ingesta del suplemento fuera durante el ejercicio. Resultados: de los veinte artículos que se incluyeron, trece obtuvieron resultados en los que la ingesta de una bebida deportiva con proteína generó mejoras significativas en el rendimiento físico en comparación con una bebida únicamente con carbohidratos y electrolitos, o un placebo. Discusión: aumentar el contenido calórico de las bebidas deportivas al agregar proteína es probablemente una estrategia más efectiva en comparación con disminuir el contenido de carbohidratos para igualar la cantidad de energía. Conclusiones: el consumo de proteína durante el ejercicio posiblemente sirva como una ayuda ergogénica, retardando el tiempo hasta llegar al agotamiento. Sin embargo, hace falta más evidencia que así lo demuestre (AU)

Introduction: sports drinks aid to improve physical performance significantly because of its content of carbohydrate, electrolytes and water. However, in recent decades it has been found that drinking a sports drink with protein during exercise improves endurance performance, produces lower losses of body weight induced by dehydration and helps to reduce post-exercise muscle damage compared to a drink only with carbohydrate and electrolytes. Purpose: the aim of this study was to analyze the main studies about the effectiveness of a supplement intake with carbohydrate, protein and electrolytes during exercise. Methods: studies were identified by searching Google Scholar, EBSCO, PubMed and Scopus using the following search terms: Carbohydrate-protein and performance and Added protein and sports drink. The methodological quality of the trials was evaluated, and It was considered that the intake of the supplement has been during exercise. Results: twenty articles were included in this study. Thirteen obtained results were the intake of sports drinks with protein produced significant improvements on endurance performance compared to beverages with carbohydrates and electrolytes alone, or a placebo. Discussion: increase the caloric content of sports drinks to add protein was probably a better strategy than reduce the carbohydrate content to match the amount of calories. Conclusions: protein intake during exercise demonstrated an ergogenic effect on endurance performance when assessed by time to exhaustion. However, we need more evidence to prove this possible ergogenic effect of protein (AU)

Novel insights on intake of meat and prevention of sarcopenia: all reasons for an adequate consumption / Nuevos conocimientos sobre el consumo de carne en la prevención de la sarcopenia: todos los motivos de un consumo adecuado

Introducion: sarcopenia is defined as a syndrome characterized by progressive and generalized loss of muscle mass and strength. The main cause of sarcopenia is the alteration of protein metabolism, in which the proteolytic processes are not accompanied by an appropriate protein synthesis and muscle cells lose progressively the sensitivity to the anabolic stimulus. The most rational approach to delay the progression of sarcopenia and counteract the anabolic resistance is proper nutrition. Meat contains biologically active compounds, such as creatine, carnitine, Conjugated Linoleic Acid (CLA) which have significant impacts upon human protein metabolism. Methods: we performed a narrative literature review to evaluate the till-now evidence regarding: 1. adequate intake of meat in elderly as a topic for prevention of sarcopenia; 2. the correct intake of biologically active compounds contain in meat, which have significant impacts upon human protein metabolism and so have beneficial effects on prevention of sarcopenia. This review included 62 eligible studies. Results: the results demonstrated that in elderly the optimum diet therapy for the sarcopenia prevention and treatment, which must aim at achieving specific metabolic goals, must recommend the consumption of 113 g of meat (220 kcal; 30 g protein) five time a week. Conclusion: in a varied and balanced diet, for preventing sarcopenia, it is recommended to assume meat 4-5 times a week (white meat 2 times per week, lean red meat less than 2 times per week, processed meat less than 1 time per week), as suggested in the diet pyramid for elderly (AU)

Introducción: la sarcopenia se define como un síndrome caracterizado por la pérdida progresiva y generalizada de la masa muscular y de la fuerza. La principal causa de la sarcopenia es la alteración del metabolismo de las proteínas, en la que los procesos proteolíticos no van acompañados de una síntesis de proteínas y células musculares adecuadas, con lo que se pierde progresivamente la sensibilidad al estímulo anabólico. El enfoque más racional para retrasar la progresión de la sarcopenia y contrarrestar la resistencia anabólica es una nutrición adecuada. La carne contiene compuestos biológicamente activos, tales como creatina, carnitina y ácido linoleico conjugado (CLA) que tienen impactos significativos sobre el metabolismo de la proteína humana. Métodos: se realizó una revisión de la literatura narrativa para evaluar la evidencia hasta ahora, en relación con: 1. ingesta adecuada de carne en ancianos como prevención de la sarcopenia; 2. la ingesta correcta de compuestos biológicamente activos que contiene la carne, que tienen impactos significativos sobre el metabolismo de la proteína humana y para así obtener efectos beneficiosos en la prevención de la sarcopenia. Esta revisión incluyó 62 estudios elegibles. Resultados: los resultados demostraron que en personas de edad avanzada la terapia óptima con dieta para la prevención y tratamiento de la sarcopenia, que debe apuntar al logro de los objetivos metabólicos específicos, debe recomendar el consumo de 113 g de carne (220 kcal; 30 g de proteínas) cinco veces a la semana. Conclusión: en una dieta variada y equilibrada, para prevenir la sarcopenia, se recomienda consumir la carne 4-5 veces a la semana (carne blanca 2 veces por semana, carne roja magra menos de 2 veces por semana, carne procesada menos de 1 vez por semana), como se sugiere en la pirámide de la dieta para personas mayores (AU)

The incremental treatment of ESRD: a low-protein diet combined with weekly hemodialysis may be beneficial for selected patients.

BACKGROUND: Infrequent dialysis, namely once-a-week session combined with very low-protein, low-phosphorus diet supplemented with ketoacids was reported as a useful treatment schedule for ESRD patients with markedly reduced residual renal function but preserved urine output. This study reports our findings from the application of a weekly dialysis schedule plus less severe protein restriction (standard low-protein low-phosphorus diet) in stage 5 CKD patients with consistent dietary discipline. METHODS: This is a multicenter, prospective controlled study, including 68 incident CKD patients followed in a pre-dialysis clinic with Glomerular Filtration Rate 5 to 10 ml/min/1.73/ m2 who became unstable on the only medical treatment. They were offered to begin a Combined Diet Dialysis Program (CDDP) or a standard thrice-a-week hemodialysis (THD): 38 patients joined the CDDP, whereas 30 patients chose THD. Patients were studied at baseline, 6 and 12 months; hospitalization and survival rate were followed-up for 24 months. RESULTS: Volume output and residual renal function were maintained in the CDDP Group while those features dropped quickly in THD Group. Throughout the study, CDDP patients had a lower erythropoietin resistance index, lower ß2 microglobulin levels and lower need for cinacalcet of phosphate binders than THD, and stable parameters of nutritional status. At 24 month follow-up, 39.4% of patients were still on CDDP; survival rates were 94.7% and 86.8% for CDDP and THD patients, respectively, but hospitalization rate was much higher in THD than in CDDP patients. The cost per patient per year resulted significantly lower in CDDP than in THD Group. CONCLUSIONS: This study shows that a CDDP served to protect the residual renal function, to maintain urine volume output and to preserve a good nutritional status. CDDP also blunted the rapid ß2 microglobulin increase and resulted in better control of anemia and calcium-phosphate abnormalities. CDDP was also associated with a lower hospitalization rate and reduced need of erythropoietin, as well as of drugs used for treatment of calcium-phosphate abnormalities, thus leading to a significant cost-saving. We concluded that in selected ESRD patients with preserved urine output attitude to protein restriction, CDDP may be a beneficial choice for an incremental hemodialysis program.

Excipient foods: designing food matrices that improve the oral bioavailability of pharmaceuticals and nutraceuticals.

The oral bioavailability of many lipophilic bioactive agents (pharmaceuticals and nutraceuticals) is limited due to various physicochemical and physiological processes: poor release from food or drug matrices; low solubility in gastrointestinal fluids; metabolism or chemical transformation within the gastrointestinal tract; low epithelium cell permeability. The bioavailability of these agents can be improved by specifically designing food matrices that control their release, solubilization, transport, metabolism, and absorption within the gastrointestinal tract. This article discusses the impact of food composition and structure on oral bioavailability, and how this knowledge can be used to design excipient foods for improving the oral bioavailability of lipophilic bioactives. Excipient foods contain ingredients or structures that may have no bioactivity themselves, but that are able to promote the bioactivity of co-ingested bioactives. These bioactives may be lipophilic drugs in pharmaceutical preparations (such as capsules, pills, or syrups) or nutraceuticals present within food matrices (such as natural or processed foods and beverages).

Relative bioavailability of iron proteinate for broilers fed a casein-dextrose diet.

An experiment was carried out to determine the bioavailability of organic Fe as Fe proteinate (Alltech, Nicholasville, KY) relative to inorganic Fe source (FeSO4•7H2O) for broiler chicks fed a casein-dextrose diet. A total of 448 1-d-old Arbor Acres commercial male broiler chicks were randomly allotted to 1 of 8 replicate cages (8 chicks per cage) for each of 7 treatments in a completely randomized design involving a 2 × 3 factorial arrangement of treatments with 2 Fe sources (Fe proteinate and Fe sulfate) and 3 levels of added Fe (10, 20, or 40 mg of Fe/kg) plus a Fe-unsupplemented control diet containing 4.56 mg of Fe/kg by analysis. Feed and distilled-deionized water were available ad libitum for an experimental phase of 14 d. At 14 d of age, blood samples were collected for testing hemoglobin (Hb) and hematocrit, and calculating total body Hb Fe, whereas liver and kidney samples were excised for Fe analyses. The results showed that ADG, ADFI, blood Hb, hematocrit, and total body Hb Fe and Fe concentrations in liver and kidney increased linearly (P < 0.0001), whereas mortality decreased linearly (P < 0.0001) as dietary Fe level increased. However, only blood Hb concentration and total body Hb Fe differed (P < 0.004) between the 2 Fe sources. Based on slope ratios from the multiple linear regression of Hb concentration and total body Hb Fe on daily intake of analyzed dietary Fe, the bioavailability of Fe proteinate relative to FeSO4•7H2O (100%) was 117 and 114%, respectively (P < 0.009). The results indicated that blood Hb concentration and total body Hb Fe were sensitive indices in reflecting differences in bioavailability among different Fe sources, and Fe proteinate was significantly more available to broilers than inorganic Fe sulfate in enhancing Hb concentration and total body Hb Fe.

Early enteral fat supplementation improves protein absorption in premature infants with an enterostomy.

BACKGROUND: Early enteral fat supplementation and fish oil (FO) stimulates post-resection intestinal adaptation in rats and increases fat absorption in premature infants with bowel resection and an enterostomy. OBJECTIVE: To test the hypothesis that early fat supplement and FO increases post-resection protein absorption, intestinal RNA, protein without decreasing intestinal arachidonic acid (AA) in premature infants with an enterostomy. METHODS: 36 premature infants (<2 months old) with an enterostomy after surgical treatment for necrotizing enterocolitis or spontaneous intestinal perforation who tolerated enteral feeding at 20 ml/kg/day were randomized to usual care (control, n = 18) or early supplementing enteral Microlipid (ML) and FO (treatment, n = 18). Intralipid was decreased as the dose of enteral fat was increased. Daily weight, ostomy output and nutritional intake were recorded. Weekly 24-hour ostomy effluent was collected to measure fecal protein. Protein absorption was calculated by subtracting fecal protein from dietary protein. Tissue samples from the functional stoma and the nonfunctional distal diverted end were collected during bowel reanastomosis to measure RNA, protein, and fatty acid (FA) profile. RESULTS: Compared to controls, the treatment group had higher protein absorption (g/kg/day) and intestinal RNA and protein (µg/mg tissue) proximal to the ostomy. The two groups had similar FA profiles except that the treatment group had higher n-3 eicosapentaenoic acid (EPA, µg/mg tissue) proximal to the ostomy. CONCLUSION: Early supplementation of enteral ML and FO to premature infants with an enterostomy increased dietary protein absorption, intestinal RNA, protein and n-3 EPA content without altering other FA content.

An addition of sourdough and whey proteins affects the nutritional quality of wholemeal wheat bread.

BACKGROUND: Bread can be a good source of nutrients as well as non-nutrient compounds. This study was designed to assess the effect of adding of sourdough and whey proteins to wholemeal (WM) bread produced by bake-off technology on chemical composition and bioavailability of proteins, calcium, phosphorus, magnesium and iron content in Wistar rats. MATERIAL AND METHODS: Wholemeal breads were baked with using conventional or bake off technology. In breads chemical composition, selected minerals content, amino acid composition were measured. Five week-old Wistar rats (n = 30, male), were randomly divided into fi ve groups and fed with modified AIN-93G diets containing experimental breads. In animal study the nutritional value of breads' proteins and concentration of selected minerals in serum, liver and femoral bone, were measured. RESULTS: The body weight gain, biological value (BV) and net protein utilization (NPU) were significantly higher in rats fed with partially baked frozen wholemeal (PBF WM) bread with sourdough and whey proteins. The level of magnesium was significantly lower in serum of animals fed with the diet containing PBF WM bread with sourdough and whey proteins in comparison to rodents fed with conventional WM bread with sourdough. The content of iron was significantly higher in liver of rats fed with PBF WM with sourdough bread in comparison to the groups fed with conventional WM and conventional WM with sourdough breads. CONCLUSIONS: Sourdough addition can be recommended in a production of whole wheat partially baked frozen bread but its use is further more beneficial if it is fermented with whey proteins.

New stable isotope method to measure protein digestibility and response to pancreatic enzyme intake in cystic fibrosis.

BACKGROUND & AIMS: Adequate protein intake and digestion are necessary to prevent muscle wasting in cystic fibrosis (CF). Accurate and easy-to-use methodology to quantify protein maldigestion is lacking in CF. OBJECTIVE: To measure protein digestibility and the response to pancreatic enzyme intake in CF by using a new stable isotope methodology. DESIGN: In 19 CF and 8 healthy subjects, protein digestibility was quantified during continuous (sip) feeding for 6 h by adding (15)N-labeled spirulina protein and L-[ring-(2)H5]phenylalanine (PHE) to the nutrition and measuring plasma ratio [(15)N]PHE to [(2)H5]PHE. Pancreatic enzymes were ingested after 2 h in CF and the response in protein digestibility was assessed. To exclude difference in mucosal function, postabsorptive whole-body citrulline (CIT) production rate was measured by L-[5-(13)C-5,5-(2)H2]-CIT pulse and blood samples were taken to analyze tracer-tracee ratios. RESULTS: Protein digestibility was severely reduced in the CF group (47% of healthy subjects; P < 0.001). Intake of pancreatic enzymes induced a slow increase in protein digestibility in CF until 90% of values obtained by healthy subjects. Maximal digestibility was reached at 100 min and maintained for 80 min. Stratification into CF children (n = 10) and adults showed comparable values for protein digestibility and similar kinetic responses to pancreatic enzyme intake. Whole-body citrulline production was elevated in CF indicating preserved mucosal function. CONCLUSION: Protein digestibility is severely compromised in patients with CF as measured by this novel and easy-to-use stable isotope approach. Pancreatic enzymes are able to normalize protein digestibility in CF, albeit with a severe delay. Registration ClinicalTrials.gov = NCT01494909.

Traditional and novel dietary interventions for preventing progression of chronic kidney disease.

Treatment of chronic kidney disease (CKD) and its complications remain largely unresolved. Currently used treatments include blood pressure control and the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which can slow down the progression of CKD but are unable to halt or reverse it. Dietary protein restriction represents an additional therapeutic measure used to slow the progression of CKD. The putative mechanisms of action responsible for its therapeutic effects include beneficial hemodynamic effects and the limitation of absorbable protein breakdown products that could lead to the accumulation of uremic waste and consequent various deleterious effects. The practical implementation of protein restriction through dietary intervention has been hindered on multiple levels, including patient nonadherence, lack of health care resources, and concerns related to adverse effects associated with the development of protein-energy wasting (PEW). As a result, alternative interventions have been designed to address some or all of these shortcomings and concerns. One such intervention is the administration of medications that prevent the absorption of protein catabolic products from the gut. This article reviews the various interventions using such a strategy to prevent or slow the progression of CKD, with special focus on recent advances in this field.

Dietary protein-induced increases in urinary calcium are accompanied by similar increases in urinary nitrogen and urinary urea: a controlled clinical trial.

To determine the usefulness of urinary urea as an index of dietary protein intake, 10 postmenopausal women were enrolled in and completed a randomized, double-blind, cross-over feeding trial from September 2008 to May 2010 that compared 10 days of a 45-g whey supplement with 10 days of a 45-g maltodextrin control. Urinary nitrogen, urinary calcium, urinary urea, and bone turnover markers were measured at days 0, 7, and 10. Paired sample t tests, Pearson's correlation statistic, and simple linear regression were used to assess differences between treatments and associations among urinary metabolites. Urinary nitrogen/urinary creatinine rose from 12.3±1.7 g/g (99.6±13.8 mmol/mmol) to 16.8±2.2 g/g (135.5±17.8 mmol/mmol) with whey supplementation, but did not change with maltodextrin. Whey supplementation caused urinary calcium to rise by 4.76±1.84 mg (1.19±0.46 mmol) without a change in bone turnover markers. Because our goal was to estimate protein intake from urinary nitrogen/urinary creatinine, we used our data to develop the following equation: protein intake (g/day)=71.221+1.719×(urinary nitrogen, g)/creatinine, g) (R=0.46, R(2)=0.21). As a more rapid and less costly alternative to urinary nitrogen/urinary creatinine, we next determined whether urinary urea could predict protein intake and found that protein intake (g/day)=63.844+1.11×(urinary urea, g/creatinine, g) (R=0.58, R(2)=0.34). These data indicate that urinary urea/urinary creatinine is at least as good a marker of dietary protein intake as urinary nitrogen and is easier to quantitate in nutrition intervention trials.

Digestibility of extruded proteins and metabolic transit of N ε -carboxymethyllysine in rats.

Milk proteins are frequently used as supplements in fortified foods. However, processing produces chemical changes which likely affect the nutritional advantage. This study was intended to explore the possible difference in digestibility between extruded and non-extruded caseins and how the dietary N (ε) -carboxymethyllysine (CML) is metabolised. Normal rats were randomized into either an extruded protein diet (EP) or the same with unextruded proteins (UEP), for two periods of 2 weeks at 7 to 9 and 11 to 13 weeks of age. However, no difference in protein digestibility was detected between the two diets, either in young or in adult animals, despite a 9.4-fold higher level of CML and an 8.5-fold higher level of lysinoalanine in the EP than in the UEP. No diet-related changes were observed in plasma CML, either protein bound or free. Amounts of 38 and 48 % of the orally absorbed CML were excreted in urine and faeces, respectively, in UEP-fed rats. Lower rates of excretion were found in the EP-fed rats (23 and 37 %, respectively). A second animal study using a single oral dose of free CML (400 µg/rat) was set up to measure the systemic concentration of CML every hour from 0 to 4 h. It revealed that protein-bound CML was not affected by the oral dose of CML, and the highest free CML level found in the circulation was 600 ng/mL. Extruded proteins, therefore, appear to be well digested, and CML rapidly eliminated. Since its elimination is, however, incomplete, the question of its biodistribution and metabolism remains open.

[Nutritional support in patients with liver cirrhosis]. / Soporte nutricional en el paciente con cirrosis hepática.

Given the liver's multiple synthetic, regulatory and detoxifying functions, one of the characteristics accompanying severe hepatocellular dysfunction is the presence of malnutrition. This disorder is highly frequent in liver cirrhosis, even in the relatively early stages of the disease. Independently of the cause of the cirrhosis, poor nutritional status is associated with a worse prognosis and therefore early intervention to correct nutrient deficiency can prolong life expectancy, improve quality of life, reduce complications and increase the probability of successful transplantation. The present article reviews current knowledge of the diagnosis and management of malnutrition in patients with cirrhosis. Special attention is paid to the concept of the late evening snack and its characteristics, composition and probable benefits in the course of the disease.

Effect of compositional alteration of food matrices and processing on availability of selected nutrients and bioactive components in rice products.

The aim was to determine the influence of compositional alteration and processing on the digestibility/availability of nutrients and bioactive components [protein (IVPD), starch (IVSD), iron, calcium, polyphenols, flavonoids] in rice products. The compositional changes representing fortified foods in 'wafers' and 'noodles' were addition of iron, rice bran, onion and cabbage. The moisture content of wafer and noodles ranged from 4.1 to 4.8% and from 73.3 to 82.1%, respectively. Wafer control (73.9-75.9%) and noodle with iron and control (85.4-87.0%) showed the highest IVPD and IVSD. Addition of rice bran decreased nutrient digestibility. The control and iron-added products exhibited least and highest available iron (2.50-2.69% and 5.99-7.07%). Total and available bioactive components increased in proportion to added external source. Overall availability of all components was better in noodles than in wafers, indicating high moisture supported higher availability. In conclusion, it can be said that both composition of the food matrix and processing influenced the availability of analyzed components.

Protein consumption following aerobic exercise increases whole-body protein turnover in older adults.

Research measuring whole-body protein turnover (WBPT) after both exercise and nutrition has generally focused on resistance exercise; however, there is a paucity of data regarding the effect of postaerobic exercise nutrition, especially in older adults. It is not known if postexercise protein feeding has a beneficial effect on protein turnover after low- to moderate-intensity exercise. We investigated whether consuming protein plus carbohydrate (PRO) immediately after an acute bout of aerobic exercise has an additive effect over carbohydrate alone (CHO) on WBPT in older individuals. Twelve healthy older adults (age, 59 ± 4 years) were studied on 2 separate occasions after 1 h of exercise at approximately 50% of maximal rate of oxygen uptake, followed by 4 h of recovery. Immediately following exercise, subjects ingested a CHO (60 g) or an isocaloric PRO beverage (40 g carbohydrate, 20 g whey protein). Whole-body protein metabolism was determined using [1-13C]leucine infusion (60 mg prime; 75 mgh(-1) continuous), and sampling blood and expired breath. Rates of whole-body leucine appearance and oxidation, and nonoxidative leucine disposal during the third and fourth hours of postexercise recovery were higher in the PRO group (2.51 ± 0.55, 0.78 ± 0.37, and 1.71 ± 0.44 micromol kg(-1)·min(-1), respectively) than in the CHO group (1.81 ± 0.27, 0.33 ± 0.14, and 1.47 ± 0.25 micromol kg(-1)·min-1, respectively; p = 0.001). Our results indicate that consumption of a PRO beverage after aerobic exercise increased WBPT to a greater extent than a CHO beverage.