The effects of antibiotic-free supplementation on the ruminal pH variability and methane emissions of beef cattle under the challenge of subacute ruminal acidosis (SARA).

Subacute ruminal acidosis (SARA) in feedlot cattle during the feed transition to grain-based diets is a significant constraint to animal health and productivity. This experiment assessed an antibiotic-free supplement (ProTect®) effects on ruminal pH variability and methane (CH4) emissions of cattle during the challenge of SARA. Ten 18-month-old Angus steers (472 ± 4.8 kg) were randomly allocated into monensin (n = 5) and ProTect® groups (n = 5) and progressively introduced to grain diets incorporating monensin or ProTect® for 36 days of the experiment [starter (7 days; 45% grain), T1 (7 days; 56% grain), T2 (7 days; 67% grain), finisher (15 days; 78% grain)]. The pH variability on the finisher period was reduced by the ProTect® supplement (6.6% vs. 5.2%; P < 0.01), with CH4 emissions being significantly higher relative to the monensin group [88.2 g/day (9.3 g CH4/kg DMI) vs. 133.7 g/day (14.1 g CH4/kg DMI); P < 0.01]. There was no difference between treatments in the time spent on the ruminal pH < 5.6 or < 5.8 (P > 0.05). The model evaluation for the ruminal pH variation indicated that the mean absolute error (MAE) proportion for both groups was good within the same range [4.05% (monensin) vs. 4.25% (ProTect®)] with identical root mean square prediction error (RMSPE) (0.34). It is concluded that the ProTect® supplement is an effective alternative to monensin for preventing SARA in feedlot cattle by managing ruminal pH variation during the transition to high-grain diets. Both monensin and ProTect® supplemented cattle exhibited lower CH4 yield compared to cattle fed forages and low-concentrate diets.

Potential of selected plant extracts to control severe subacute ruminal acidosis in vitro as compared with monensin.

BACKGROUND: In recent years, researchers have become increasingly interested in developing natural feed additives that can stabilize ruminal pH and thus prevent or eliminate the risk of severe subacute rumen acidosis. Herein, 3 experiments were conducted using a semi-automated in vitro gas production technique. In the experiment (Exp.) 1, the efficacy of 9 plant extracts (1.5 mg/ml), compared to monensin (MON; 12 µg/ml), to counteract ruminal acidosis stimulated by adding glucose (0.1 g/ml) as a fermentable carbohydrate without buffer was assessed for 6 h. In Exp. 2, cinnamon extract (CIN) and MON were evaluated to combat glucose-induced acidosis with buffer use for 24 h. In Exp. 3, the effect of CIN and MON on preventing acidosis when corn or barley grains were used as substrate was examined. RESULTS: In Exp. 1, cinnamon, grape seeds, orange, pomegranate peels, propolis, and guava extracts significantly increased (P < 0.05) pH compared to control (CON). Both CIN and MON significantly increased the pH (P < 0.001) but reduced cumulated gas production (P < 0.01) compared to the other treatments. In Exp. 2, the addition of CIN extract increased (P < 0.01) pH value compared to CON at the first 6 h of incubation. However, no significant differences in pH values between CIN and CON at 24 h of incubation were observed. The addition of CIN extract and MON decreased (P < 0.001) lactic acid concentration and TVFA compared to CON at 24 h. The CIN significantly (P < 0.01) increased acetate: propionate ratio while MON reduced it. In Exp. 3, both CIN and MON significantly increased (P < 0.05) ruminal pH at 6 and 24 h and reduced lactic acid concentration at 24 h compared to CON with corn as substrate. However, CIN had no effect on pH with barley substrate at all incubation times. CONCLUSIONS: It can be concluded that CIN can be used effectively as an alternative antibiotic to MON to control ruminal acidosis when corn is used as a basal diet.

Nutritional Approaches for the Management of Metabolic Acidosis in Chronic Kidney Disease.

Metabolic acidosis is a severe complication of chronic kidney disease (CKD) which is associated with nefarious impairments such as bone demineralization, muscle wasting, and hormonal alterations, for example, insulin resistance. Whilst it is possible to control this condition with alkali treatment, consisting in the oral administration of sodium citrate or sodium bicarbonate, this type of intervention is not free from side effects. On the contrary, opting for the implementation of a targeted dietetic-nutritional treatment for the control of CKD metabolic acidosis also comes with a range of additional benefits such as lipid profile control, increased vitamins, and antioxidants intake. In our review, we evaluated the main dietary-nutritional regimens useful to counteract metabolic acidosis, such as the Mediterranean diet, the alkaline diet, the low-protein diet, and the vegan low-protein diet, analyzing the potentialities and limits of every dietary-nutritional treatment. Literature data suggest that the Mediterranean and alkaline diets represent a valid nutritional approach in the prevention and correction of metabolic acidosis in CKD early stages, while the low-protein diet and the vegan low-protein diet are more effective in CKD advanced stages. In conclusion, we propose that tailored nutritional approaches should represent a valid therapeutic alternative to counteract metabolic acidosis.

Potential protective effects of thiamine supplementation on the ruminal epithelium damage during subacute ruminal acidosis.

In ruminants, the ruminal epithelium not only has the function of absorbing nutrients but also is an important tissue to prevent harmful substances in the rumen from entering the blood circulation. Thus, the normal function of ruminal epithelium is critical for ruminants. However, subacute ruminal acidosis induced by high-concentrate diets often damages the barrier function of ruminal epithelium in ruminants. Recently, many studies have shown that dietary supplementation with thiamine is an effective method to alleviate subacute ruminal acidosis. In order to provide theoretical reference for the in-depth study of subacute ruminal acidosis and the application of thiamine in the future, this review introduces the effects of subacute ruminal acidosis on morphological structure, inflammatory response, and tight junction of ruminal epithelium. In addition, this paper summarizes the role of thiamine in maintaining ruminal epithelial function of ruminants during subacute ruminal acidosis challenge.

Inhaled H2 or CO2 Do Not Augment the Neuroprotective Effect of Therapeutic Hypothermia in a Severe Neonatal Hypoxic-Ischemic Encephalopathy Piglet Model.

Hypoxic-ischemic encephalopathy (HIE) is still a major cause of neonatal death and disability as therapeutic hypothermia (TH) alone cannot afford sufficient neuroprotection. The present study investigated whether ventilation with molecular hydrogen (2.1% H2) or graded restoration of normocapnia with CO2 for 4 h after asphyxia would augment the neuroprotective effect of TH in a subacute (48 h) HIE piglet model. Piglets were randomized to untreated naïve, control-normothermia, asphyxia-normothermia (20-min 4%O2-20%CO2 ventilation; Tcore = 38.5 °C), asphyxia-hypothermia (A-HT, Tcore = 33.5 °C, 2-36 h post-asphyxia), A-HT + H2, or A-HT + CO2 treatment groups. Asphyxia elicited severe hypoxia (pO2 = 19 ± 5 mmHg) and mixed acidosis (pH = 6.79 ± 0.10). HIE development was confirmed by altered cerebral electrical activity and neuropathology. TH was significantly neuroprotective in the caudate nucleus but demonstrated virtually no such effect in the hippocampus. The mRNA levels of apoptosis-inducing factor and caspase-3 showed a ~10-fold increase in the A-HT group compared to naïve animals in the hippocampus but not in the caudate nucleus coinciding with the region-specific neuroprotective effect of TH. H2 or CO2 did not augment TH-induced neuroprotection in any brain areas; rather, CO2 even abolished the neuroprotective effect of TH in the caudate nucleus. In conclusion, the present findings do not support the use of these medical gases to supplement TH in HIE management.

Potassium citrate and metabolic acidosis in children with epilepsy on the ketogenic diet: a prospective controlled study.

AIM: To investigate if potassium citrate, a mild alkaline compound, can prevent metabolic acidosis in children with epilepsy treated with the ketogenic diet without reducing antiepileptic efficacy. METHOD: In this prospective controlled study, we investigated the frequency of initial uncompensated metabolic acidosis in 51 participants. There were 22 participants with and 29 without potassium citrate supplementation. The ketogenic diet was used as add-on treatment to children with drug resistant epilepsy. We also estimated the proportion of participants with a greater than 50% seizure reduction after 7 months. RESULTS: None of the 22 participants (15 males, seven females; median age 1y 7mo, interquartile range [IQR] 3y 3mo) with, and 10 of 29 (12 males, 17 females; median age 6y 1mo, IQR 4y 8mo) without potassium citrate developed metabolic acidosis (odds ratio=0.04, 95% CI 0.00-0.75 [p<0.01]); median pH 7.32 vs 7.24; [p<0.001]), and median bicarbonate 19.7mmol/L vs 14.0mmol/L (p<0.001). The number of seizures was reduced by more than 50% in 9 of 22 with potassium citrate and 8 of 29 participants without potassium citrate, 7 months after introducing a ketogenic diet (p=0.4). INTERPRETATION: In the ketogenic diet, potassium citrate supplementation can prevent metabolic acidosis, without reducing antiepileptic efficacy. WHAT THIS PAPER ADDS: Citrate supplementation prevents metabolic acidosis in children treated with a ketogenic diet. Efficacy of the ketogenic diet is not affected by supplementation with citrate. Citrate supplementation does not affect beta-hydroxybuturate concentration. Potassium citrate reduces the time needed to reach an optimal ketogenic ratio. This article is commented on by Schoeler on page 8 of this issue.

[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.

Evaluation of active dried yeast in the diets of feedlot steers. II. Effects on rumen pH and liver health of feedlot steers1.

The objective of this trial was to determine the benefits of supplementing active dried yeast (ADY; 3 × 1010 CFU/d of Saccharomyces cerevisiae) in diets of growing and finishing steers on ruminal pH and liver health, and evaluate the relationship of these variables with performance traits. Growing beef steers (n = 120) were blocked by weight (i.e., heavy and light) and allocated to 1 of 4 pens in an automated feed intake monitoring system. Steers were fed either control (CON; no ADY) or ADY supplemented in 4 sequential diets: grower diet from days 0 to 70, 2 step up diets (STEP1 and STEP2) for 7 d each, and finishing diet from days 85 to 164. Indwelling rumen boli were administered to monitor rumen pH during days 56 to 106 during the dietary transition. An exchange of pen assignment, within block, occurred on day 70 resulting in 4 final treatment (TRT) assignments: steers fed CON before and after the exchange (CC; n = 30), steers fed CON before and ADY after the exchange (CY; n = 30), steers fed ADY before and CON after the exchange (YC; n = 30), and steers fed ADY (YY; n = 30). Ruminal parameters were analyzed as a randomized complete block design with repeated measures of day, diet and TRT as fixed effects, and block as random effects, using 2 approaches: preliminary analysis of the means or drift analysis (DA; units change from basal values over time). Ruminal pH duration (DUR) below 6.0 (P = 0.05) and 5.8 (P = 0.05) was greater for CY steers than CC steers. Acidosis bout prevalence (pH < 5.6 for 180 consecutive minutes; P < 0.01) and bout DUR (P = 0.05) were greater for CY than other TRT groups. The DA indicated that the ruminal pH variables range, variance, and amplitude of steers in the YC group drifted further from basal pH values than CY and YY steers during the dietary transition (P ≤ 0.02), indicating that removing ADY during the dietary transition was not favorable, but including ADY may reduce ruminal fluctuation. Steers with fewer days experiencing bouts (DEB) had numerically greater ADG (P = 0.11) and tended to have greater G:F (P = 0.06). Liver abscess severity negatively affected ADG (P = 0.04). However, liver abscess severity was not affected by DEB (P = 0.90). There is evidence to suggest that the addition of the specific ADY strain in the diets of beef cattle during the dietary transition may aid in ruminal stabilization, but our study did not find evidence that acidosis bouts were related to abscess prevalence or severity.

Control of metabolic predisposition to cardiovascular complications of chronic kidney disease by effervescent calcium magnesium citrate: a feasibility study.

AIMS: Cardiovascular (CV) complications are common in chronic kidney disease (CKD). Numerous metabolic disturbances including hyperphosphatemia, high circulating calciprotein particles (CPP), hyperparathyroidism, metabolic acidosis, and magnesium deficiency are associated with, and likely pathogenic for CV complications in CKD. The goal of this feasibility study was to determine whether effervescent calcium magnesium citrate (EffCaMgCit) ameliorates the aforementioned pathogenic intermediates. METHODS: Nine patients with Stage 3 and nine patients with Stage 5D CKD underwent a randomized crossover study, where they took EffCaMgCit three times daily for 7 days in one phase, and a conventional phosphorus binder calcium acetate (CaAc) three times daily for 7 days in the other phase. Two-hour postprandial blood samples were obtained on the day before and on the 7th day of treatment. RESULTS: In Stage 5D CKD, EffCaMgCit significantly increased T50 (half time for conversion of primary to secondary CPP) from baseline by 63% (P = 0.013), coincident with statistically non-significant declines in serum phosphorus by 25% and in saturation of octacalcium phosphate by 35%; CaAc did not change T50. In Stage 3 CKD, neither EffCaMgCit nor CaAc altered T50. With EffCaMgCit, a significant increase in plasma citrate was accompanied by statistically non-significant increase in serum Mg and phosphate. CaAc was without effect in any of these parameters in Stage 3 CKD. In both Stages 3 and 5D, both drugs significantly reduced serum parathyroid hormone. Only EffCaMgCit significantly increased serum bicarbonate by 3 mM (P = 0.015) in Stage 5D. CONCLUSIONS: In Stage 5D, EffCaMgCit inhibited formation of CPP, suppressed PTH, and conferred magnesium and alkali loads. These effects were unique, since they were not observed with CaAc. In Stage 3 CKD, neither of the regimens have any effect. These metabolic changes suggest that EffCaMgCit might be useful in protecting against cardiovascular complications of CKD by ameliorating pathobiologic intermediates.

The function of geophagy in Nepal gray langurs: Sodium acquisition rather than detoxification or prevention of acidosis.

OBJECTIVES: Geophagy has several hypothesized functions, among them (1) detoxification of plant secondary compounds, for example, tannins, (2) buffering stomach pH to alleviate acidosis caused by high sugar intake, and (3) supplementing the diet with mineral nutrients. We tested these hypotheses in Nepal gray langurs (Semnopithecus schistaceus), a foregut fermenter for which fruits and leaves dominate the diet at different times of the year. MATERIALS AND METHODS: We collected data on feeding time per food item for 21 unprovisioned adult langurs at Ramnagar, Nepal, for 1 year using instantaneous sampling (773 observation hours). We combined these data with relative sugar and tannin content of food items to estimate diet content. We collected rainfall data to distinguish the wet season (May-September) from the dry season (October-April). We collected soil samples from consumption and control sites to test for pH and sodium, potassium, magnesium, and calcium concentrations. RESULTS: Langurs consumed soil from two sources: termite structures (in almost all months) and river banks and beds (mainly in the dry season). Soil feeding was not positively correlated with dietary tannin or sugar content (GLMM). Soil pH was not high enough to buffer stomach contents. Only sodium was significantly higher in consumed soil. DISCUSSION: The most likely function of geophagy was the acquisition of sodium. This conclusion is consistent with reports for other animals. Buffering stomach pH, an often-suggested function for animals with ruminant-like digestion, was not supported. Detoxification, often proposed for animals with a diet high in secondary compounds, was also not supported.

Invited review: Practical feeding management recommendations to mitigate the risk of subacute ruminal acidosis in dairy cattle.

Rumen health is of vital importance in ensuring healthy and efficient dairy cattle production. Current feeding programs for cattle recommend concentrate-rich diets to meet the high nutritional needs of cows during lactation and enhance cost-efficiency. These diets, however, can impair rumen health. The term "subacute ruminal acidosis" (SARA) is often used as a synonym for poor rumen health. In this review, we first describe the physiological demands of cattle for dietary physically effective fiber. We also provide background information on the importance of enhancing salivary secretions and short-chain fatty acid absorption across the stratified squamous epithelium of the rumen; thus, preventing the disruption of the ruminal acid-base balance, a process that paves the way for acidification of the rumen. On-farm evaluation of dietary fiber adequacy is challenging for both nutritionists and veterinarians; therefore, this review provides practical recommendations on how to evaluate the physical effectiveness of the diet based on differences in particle size distribution, fiber content, and the type of concentrate fed, both when the latter is part of total mixed ration and when it is supplemented in partial mixed rations. Besides considering the absolute amount of physically effective fiber and starch types in the diet, we highlight the role of several feeding management factors that affect rumen health and should be considered to control and mitigate SARA. Most importantly, transitional feeding to ensure gradual adaptation of the ruminal epithelium and microbiota; monitoring and careful management of particle size distribution; controlling feed sorting, meal size, and meal frequency; and paying special attention to primiparous cows are some of the feeding management tools that can help in sustaining rumen health in high-producing dairy herds. Supplementation of feed additives including yeast products, phytogenic compounds, and buffers may help attenuate SARA, especially during stress periods when the risk of a deficiency of physically effective fiber in the diet is high, such as during early lactation. However, the usage of feed additives cannot fully compensate for suboptimal feeding management.

Modulation of chewing behavior and reticular pH in nonlactating cows challenged with concentrate-rich diets supplemented with phytogenic compounds and autolyzed yeast.

Feeding of concentrate-rich diets impairs chewing behavior and leads to rumen acidosis in cattle. Because of their modulatory effects on ruminal fermentation, phytogenic compounds (PHY) and autolyzed yeast derivatives (AY) may alleviate the negative consequences of high-concentrate diets. Therefore, this research investigated if chewing behavior and the reticular pH dynamics are modulated by AY and PHY supplementation during repeated concentrate-rich challenges used to simulate intermittent rumen acidotic insults. Eight rumen-cannulated, dry, and nonpregnant Holstein cows were assigned to an incomplete double 4 × 3 Latin square design with 3 treatments and 4 experimental runs (n = 8/treatment). Cows were fed concentrates either not supplemented (CON) or supplemented with PHY or AY. Initially, cows were fed a pure forage diet (FD) and switched to a 65% concentrate diet on DM basis for 1 (CONC 1) and 2 (CONC 2) wk. Between CONC 1 and CONC 2, the cows were fed the FD for 1 wk. Chewing activity was measured using noseband sensors and reticular pH by wireless pH sensors. Data showed that cows spent less time ruminating in CONC 1 than in CONC 2. In agreement, reticular pH drop was more pronounced during CONC 1 than during CONC 2. Cows fed with PHY spent 4 h less with reticular pH <6.0 during CONC 1 and 3 h less with pH <6.0 h in CONC 2 as compared with CON cows. Similarly, PHY supplementation extended rumination time with 88 min/d compared with CON cows during CONC 1. The AY supplementation increased DMI by 20% resulting in a longer eating time compared with CON diet during CONC 1. Enhancement of ruminating by PHY and eating time by AY supplementation resulted in longer total chewing time for PHY (474 min/d) and AY (466 min/d) as compared with CON (356 min/d) in CONC 1. In conclusion, cows experiencing 2 intermittent concentrate-rich challenges increased their ruminating behavior during the second challenge, and this effect was associated with higher reticular pH readings. The PHY supplementation enhanced rumination as well as reticular pH during CONC 1. However, the enhanced pH of cows fed with PHY during CONC 2 was not related to greater rumination, suggesting that influencing factors beyond rumination seemed to play a role in modulating reticular pH in PHY cows during CONC 2. The AY supplementation increased DMI without depressing rumination or reticular pH. Effects of both feed additives were more pronounced during CONC 1 challenge when reticular pH was lower.

Comparison of a commercially available oral nutritional supplement and intravenous fluid therapy for dehydration in dairy calves.

Calf scours is a primary cause of morbidity and mortality in the dairy industry. Effective treatments are needed to minimize death, maximize welfare, and maintain growth and productivity. The objective of this trial was to compare the efficacy of a commercially available nutritional supplement (Diaque, Boehringer-Ingelheim Vetmedica Inc., St. Joseph, MO) and i.v. lactated Ringer's solution (LRS) in rehydrating, preventing acidemia, and correcting electrolyte imbalances in an experimental model for calf scours. Twenty-four colostrum-fed suckling dairy calves were used in a modified crossover design. An osmotic diarrhea was induced by orally feeding commercial milk replacer modified with high level of sucrose to create a hypertonic milk solution, and administering oral hydrochlorothiazide and spironolactone for 48 h. The intention was to create a challenge sufficient to result in moderately dehydrated, standing calves without producing severe depression or loss of suckle. The efficacy of i.v. fluid therapy and a commercial nutritional supplement were subsequently compared for reversing the effects of the diarrheal disease. Treatment A consisted of administering the nutritional supplement according to label directions (100 g in 1.9 L of warm water, 3 times a day), and treatment B consisted of i.v. LRS (2 L, once a day). Clinical signs and laboratory results were obtained once daily by a blinded observer. The induction method was effective in creating the desired effect, as demonstrated by weight loss and subjective health and hydration scores. Both treatment groups experienced increases in body weight, base excess, and bicarbonate, and decreases in total protein and packed cell volume following treatment. Both i.v. LRS and Diaque are effective methods to correct hypovolemia and control derangements in acid-base status in calves with diarrhea and dehydration.

Rumen microbial and fermentation characteristics are affected differently by acarbose addition during two nutritional types of simulated severe subacute ruminal acidosis in vitro.

Little information is available on whether or not the effect of an alpha-glucosidase inhibitor on the prevention of ruminal acidosis is influenced by the type of diet during ruminant feeding. This study was conducted to explore the effect of acarbose addition on the prevention of severe subacute ruminal acidosis induced by either cracked wheat or beet pulp in vitro. Cracked wheat and beet pulp were fermented in vitro by rumen microorganisms obtained from three dairy cows. When cracked wheat was used as the substrate and fermented for 24 h, compared with the control, acarbose addition decreased the concentrations of acetate, propionate, butyrate, total volatile fatty acids, and lactate (P < 0.05), while linearly increased the ratio of acetate to propionate, pH value, and the ammonia-nitrogen level (P < 0.05). Applying Illumina MiSeq sequencing of a fragment of the 16S rRNA gene revealed that the relative abundance of Firmicutes and Bacteroidetes as well as the ACE (abundance-based coverage estimator) value, Chao 1 value, and Shannon index increased significantly (P < 0.05), while there was a significant reduction (P < 0.05) in the relative abundance of Tenericutes as well as Proteobacteria after adding acarbose compared to the control. On the other hand, when beet pulp was used as the substrate, acarbose addition had no significant effects (P > 0.05) on the fermentation parameters and the Chao 1 value, the Shannon index, and the proportion of Firmicutes and Bacteroidetes. In general, these findings indicate that acarbose had more effects on ruminal fermentation when wheat was used as the substrate, whereas it exhibited little effect on ruminal fermentation when beet pulp was used as the substrate.

Nutritional Strategies to Modulate Intracellular and Extracellular Buffering Capacity During High-Intensity Exercise.

Intramuscular acidosis is a contributing factor to fatigue during high-intensity exercise. Many nutritional strategies aiming to increase intra- and extracellular buffering capacity have been investigated. Among these, supplementation of beta-alanine (~3-6.4 g/day for 4 weeks or longer), the rate-limiting factor to the intramuscular synthesis of carnosine (i.e. an intracellular buffer), has been shown to result in positive effects on exercise performance in which acidosis is a contributing factor to fatigue. Furthermore, sodium bicarbonate, sodium citrate and sodium/calcium lactate supplementation have been employed in an attempt to increase the extracellular buffering capacity. Although all attempts have increased blood bicarbonate concentrations, evidence indicates that sodium bicarbonate (0.3 g/kg body mass) is the most effective in improving high-intensity exercise performance. The evidence supporting the ergogenic effects of sodium citrate and lactate remain weak. These nutritional strategies are not without side effects, as gastrointestinal distress is often associated with the effective doses of sodium bicarbonate, sodium citrate and calcium lactate. Similarly, paresthesia (i.e. tingling sensation of the skin) is currently the only known side effect associated with beta-alanine supplementation, and it is caused by the acute elevation in plasma beta-alanine concentration after a single dose of beta-alanine. Finally, the co-supplementation of beta-alanine and sodium bicarbonate may result in additive ergogenic gains during high-intensity exercise, although studies are required to investigate this combination in a wide range of sports.

Biological Impact of Recent Guidelines on Parenteral Nutrition in Preterm Infants.

OBJECTIVES: Recent guidelines for preterm neonates recommend early initiation of parenteral nutrition (PN) with high protein and relatively high caloric intake. This review considers whether these changes could influence homeostasis in very preterm infants during the first few postnatal weeks. METHODS: This systematic review of relevant literature from searches of PubMed and recent guidelines was reviewed by investigators from several perinatal centers in France. RESULTS: New recommendations for PN could be associated with metabolic acidosis via the increase in the amino acid ion gap, hyperchloremic acidosis, and ammonia acidosis. The introduction of high-intake amino acids soon after birth could induce hypophosphatemia and hypercalcemia, simulating a "repeat feeding-like syndrome" and could be prevented by the early intake of phosphorus, especially in preterm infants born after fetal growth restriction. Early high-dose amino acid infusions are relatively well tolerated in the preterm infant with regard to renal function. Additional studies, however, are warranted to determine markers of protein intolerance and to specify the optimal composition and amount of amino acid solutions. CONCLUSIONS: Optimal PN following new guidelines in very preterm infants, despite their demonstrated benefits on growth, may induce adverse effects on ionic homeostasis. Clinicians should implement appropriate monitoring to prevent and/or correct them.

Electrolyte and Mineral Homeostasis After Optimizing Early Macronutrient Intakes in VLBW Infants on Parenteral Nutrition.

OBJECTIVES: The aim of the present study was to evaluate electrolyte and mineral homeostasis in very-low-birth-weight (VLBW) infants who received high protein and energy intakes with a unique standardized parenteral nutrition solution containing electrolytes and minerals from birth onward. METHODS: Prospective cohort study in 102 infants with birth weight <1250 g. The evolution of plasma biochemical parameters was described during the first 2 weeks of life. RESULTS: During the first 3 days of life, mean parenteral intakes were 51 ±â€Š8 kcal · kg · day with 2.7 ±â€Š0.4 g · kg · day of protein, 1.1 ±â€Š0.2 mmol · kg · day of sodium and potassium, and 1.3 ±â€Š0.2 mmol · kg · day of calcium and phosphorus. Afterwards, most nutritional intakes (parenteral and enteral) met growth requirements. No infant developed a hyperkalemia >7 mmol/L, and a hypernatremia >150 mmol/L occurred only in 15.7% of the infants. In contrast, hyponatremia <130 mmol/L and hypokalemia <3 mmol/L occurred in 30.4% and 8.8% of the infants, respectively. The initial neonatal metabolic acidosis rapidly resolved in most infants and only 2.0% developed a base deficit >10 mmol/L after day 3 of life. Early hypocalcemia <1.8 mmol/L occurred in 13.7% of the infants. In contrast, hypophosphatemia <1.6 mmol/L occurred in 37.3% and hypercalcemia >2.8 mmol/L occurred in 12.7% of the infants. CONCLUSIONS: Increasing early protein and energy intakes in VLBW infants in the first week of life improves electrolyte homeostasis. It also increases the phosphorus requirements with a calcium-to-phosphorus ratio ≤1.0 (mmol/mmol) and the potassium and sodium requirements to avoid the development of a refeeding-like syndrome. These data suggest that the parenteral nutrition guidelines for VLBW infants for the first week of life need to be revised.

Doubling of muscle carnosine concentration does not improve laboratory 1-hr cycling time-trial performance.

Muscle carnosine loading through chronic oral beta-alanine supplementation has been shown to be effective for short-duration, high-intensity exercise. This randomized, placebo-controlled study explored whether the ergogenic effect of beta-alanine supplementation is also present for longer duration exercise. Subjects (27 well-trained cyclists/triathletes) were supplemented with either beta-alanine or placebo (6.4 g/day) for 6 weeks. Time to completion and physiological variables for a 1-hr cycling time-trial were compared between preand postsupplementation. Muscle carnosine concentration was also assessed via proton magnetic resonance spectroscopy before and after supplementation. Following beta-alanine supplementation, muscle carnosine concentration was increased by 143 ± 151% (mean ± SD; p < .001) in the gastrocnemius and 161 ± 56% (p < .001) in the soleus. Postsupplementation time trial performance was significantly slower in the placebo group (60.6 ± 4.4-63.0 ± 5.4 min; p < .01) and trended toward a slower performance following beta-alanine supplementation (59.8 ± 2.8-61.7 ± 3.0 min; p = .069). We found an increase in lactate/proton concentration ratio following beta-alanine supplementation during the time-trial (209.0 ± 44.0 (beta-alanine) vs. 161.9 ± 54.4 (placebo); p < .05), indicating that a similar lactate concentration was accompanied by a lower degree of systemic acidosis, even though this acidosis was quite moderate (pH ranging from 7.30 to 7.40). In conclusion, chronic beta-alanine supplementation in well-trained cyclists had a very pronounced effect on muscle carnosine concentration and a moderate attenuating effect on the acidosis associated with lactate accumulation, yet without affecting 1-h time-trial performance under laboratory conditions.

Vegetarianism: advantages and drawbacks in patients with chronic kidney diseases.

Vegetarian diet is a very old practice that is liable to confer some health benefits. Recent studies have demonstrated that modification of the dietary pattern with a reduction of animal protein intake and increased consumption of plant-based foods could influence cardiovascular risk profile and mortality rate. Moreover, phosphate bioavailability from plant proteins is reduced. These statements could lead to some benefits for chronic kidney disease (CKD) patients. This review summarizes the characteristics and benefits of vegetarian diets in the general population and the potential beneficial effects of such a diet on phosphate balance, insulin sensitivity, and the control of metabolic acidosis in CKD patients. Potential drawbacks exist when a vegetarian diet is associated with protein intake that is too restrictive and/or insufficient energy intake, justifying an early and regular nutritional follow-up jointly assumed by a nephrologist and a renal dietitian.