Nonessential amino acid usage for protein replenishment in humans: a method of estimation

Targeted metabolomic analysis of serum amino acids in heart failure patients

Heart failure (HF) has been recognized as a global epidemic with high rates of morbidity, hospitalization, and mortality. The role of amino acids, which provide the body with energy, in the development of HF is still unclear. The aim of this study was to explore changes in serum amino acids in patients with HF and identify potential biomarkers. First, the serum amino acid metabolism profiles of 44 patients with HF and 30 healthy controls (Con) were quantitatively measured. Then, candidate markers were identified through the utilization of T test, multivariate statistical analysis, and receiver operating characteristic (ROC) curve analysis. The results found that there were 11 amino acid levels that were significantly different between patients with HF and Con. Based on ROC curve analysis, the biomarkers of eight amino acids (Glutamic acid, Taurine, L-aspartic acid, L-ornithine, Ethanolamine, L-Serine, L-Sarcosine, and Cysteine) showed high sensitivity and specificity (AUC > 0.90), and binary logistic regression analysis was used in MetaboAnalyst 5.0. Among the amino acids examined, six exhibited notable alterations in accordance with the severity of HF. In conclusion, this study cannot only provide clinicians with an objective diagnostic approach for the early identification of HF, but also enhances comprehension of the underlying mechanisms involved in the pathogenesis of HF.

Personalized Nutritional Strategies to Reduce Knee Osteoarthritis Severity and Ameliorate Sarcopenic Obesity Indices: A Practical Guide in an Orthopedic Setting

Knee osteoarthritis (KOA) is one of the most common joint diseases, especially in individuals with obesity. Another condition within this population, and which presents frequently, is sarcopenic obesity (SO), defined as an increase in body fat and a decrease in muscle mass and strength. The current paper aims to describe recent nutritional strategies which can generally improve KOA clinical severity and, at the same time, ameliorate SO indices. Searches were carried out in the PubMed and Science Direct databases and data were summarized using a narrative approach. Certain key findings have been revealed. Firstly, the screening and identification of SO in patients with KOA is important, and to this end, simple physical performance tests and anthropometric measures are available in the literature. Secondly, adherence to a Mediterranean diet and the achievement of significant body weight loss by means of low-calorie diets (LCDs) remain the cornerstone nutritional treatment in this population. Thirdly, supplementation with certain micronutrients such as vitamin D, essential and non-essential amino acids, as well as whey protein, also appear to be beneficial. In conclusion, in the current review, we presented a detailed flowchart of three different nutritional tracks that can be adopted to improve both KOA and SO based on joint disease clinical severity.

Is It Time to Reconsider the U.S. Recommendations for Dietary Protein and Amino Acid Intake?

Since the U.S. Institute of Medicine's recommendations on protein and amino acid intake in 2005, new information supports the need to re-evaluate these recommendations. New lines of evidence include: (1) re-analysis/re-interpretation of nitrogen balance data; (2) results from indicator amino acid oxidation studies; (3) studies of positive functional outcomes associated with protein intakes higher than recommended; (4) dietary guidance and protein recommendations from some professional nutrition societies; and (5) recognition that the synthesis of certain dispensable amino acids may be insufficient to meet physiological requirements more often than previously understood. The empirical estimates, theoretical calculations and clinical functional outcomes converge on a similar theme, that recommendations for intake of protein and some amino acids may be too low in several populations, including for older adults (≥65 years), pregnant and lactating women, and healthy children older than 3 years. Additional influential factors that should be considered are protein quality that meets operational sufficiency (adequate intake to support healthy functional outcomes), interactions between protein and energy intake, and functional roles of amino acids which could impact the pool of available amino acids for use in protein synthesis. Going forward, the definition of "adequacy" as it pertains to protein and amino acid intake recommendations must take into consideration these critical factors.

Role of gut microbe-derived metabolites in cardiometabolic diseases: Systems based approach

BACKGROUND

The gut microbiome influences host physiology and cardiometabolic diseases by interacting directly with intestinal cells or by producing molecules that enter the host circulation. Given the large number of microbial species present in the gut and the numerous factors that influence gut bacterial composition, it has been challenging to understand the underlying biological mechanisms that modulate risk of cardiometabolic disease.

SCOPE OF THE REVIEW

Here we discuss a systems-based approach that involves simultaneously examining individuals in populations for gut microbiome composition, molecular traits using "omics" technologies, such as circulating metabolites quantified by mass spectrometry, and clinical traits. We summarize findings from landmark studies using this approach and discuss future applications.

MAJOR CONCLUSIONS

Population-based integrative approaches have identified a large number of microbe-derived or microbe-modified metabolites that are associated with cardiometabolic traits. The knowledge gained from these studies provide new opportunities for understanding the mechanisms involved in gut microbiome-host interactions and may have potentially important implications for developing novel therapeutic approaches.

Treatment-Interval Changes in Serum Levels of Albumin and Histidine Correlated with Treatment Interruption in Patients with Locally Advanced Head and Neck Squamous Cell Carcinoma Completing Chemoradiotherapy under Recommended Calorie and Protein Provision

We investigated risk factors for treatment interruption (TI) in patients with locally advanced head and neck squamous-cell carcinoma (LAHNSCC) following concurrent chemoradiotherapy (CCRT), under the provision of recommended calorie and protein intake; we also evaluated the associations between clinicopathological variables, calorie and protein supply, nutrition–inflammation biomarkers (NIBs), total body composition change (TBC), and a four-serum-amino-acid metabolite panel (histidine, leucine, ornithine, and phenylalanine) among these patients. Patients with LAHNSCC who completed the entire planned CCRT course and received at least 25 kcal/kg/day and 1 g of protein/kg/day during CCRT were prospectively recruited. Clinicopathological variables, anthropometric data, blood NIBs, CCRT-related factors, TBC data, and metabolite panels before and after treatment were collected; 44 patients with LAHNSCC were enrolled. Nine patients (20.4%) experienced TIs. Patients with TIs experienced greater reductions in hemoglobin, serum levels of albumin, uric acid, histidine, and appendicular skeletal mass, and suffered from more grade 3/4 toxicities than those with no TI. Neither increased daily calorie supply (≥30 kcal/kg/day) nor feeding tube placement was correlated with TI. Multivariate analysis showed that treatment-interval changes in serum albumin and histidine levels, but not treatment toxicity, were independently associated with TI. Thus, changes in serum levels of albumin and histidine over the treatment course could cause TI in patients with LAHNSCC following CCRT.

A way forward for the South African quail sector as a potential contributor to food and nutrition security following the aftermath of COVID-19: a review

Commercial quail (Coturnix coturnix) farming has recently gained recognition from the South African poultry industry as a potential source of protein, which can be used to alleviate protein-energy malnutrition as well as food and nutrition insecurity in rural South Africa. Over six large-scale and hundred small-scale farmers are currently producing various quail breeds for commercial purposes in South Africa. However, these farmers face challenges of high feed costs, diseases, poor health care, low demand (for quail meat and eggs) and limited access to the markets. In addition, the lack of a pre-existing local market for quail meat and eggs has seen most farmers exporting these products to other countries, but with low profit margins owing to the slow growth experienced by world economies. Furthermore, the socio-economic crisis brought by the global Coronavirus Disease 2019 (COVID-19) pandemic has exacerbated these challenges as most of the countries enforced nationwide lockdown to mitigate the spread of the virus. Although this initiative was taken to save lives, it left quail farmers not knowing where to trade their stock due to large uncertainties in the social and economic domain, compounded by the fact that many South African citizens are traditionally accustomed to chicken products. Moreover, the size of the quail in relation to its market price when compared to that of chickens continues to lower its demand causing a lot of quail businesses to collapse. Thus, it is imperative to explore strategies that can reduce the cost of producing quail, while increasing their demand and popularity. Non-conventional feed ingredients and phytogenic feed additives that are inexpensive, locally available, and readily accessible should be identified and evaluated in quail diets to deliver sustainable production systems that will ensure that these birds continue to play a significant role in food and nutrition security of humans. In addition, extension service workers and quail farmers need to form a collaborative team to increase awareness about the benefits of quail products and build a long-lasting and profitable quail business. In this work, we present potential rearing methods for commercial quail production, nutritional benefits of quail products, as well as nutritional solutions for a sustainable and profitable quail business. Lastly, we review prospective awareness programs and marketing strategies that are aimed at successful commercialisation of quail using various networks.

A discussion on the 'dispensable' amino acids

PURPOSE OF REVIEW

Recently, the concept of dietary dispensable amino acids has been increasingly challenged, as more indirect and direct (experimental) evidence has pointed to the need for them in the diet during specific life stages or disease states. Here, we discuss the classification of amino acids, methods to assess the needs for dispensable amino acids with experimental evidence from our recent studies, and highlight the role of specific dispensable amino acids in metabolism and health.

RECENT FINDINGS

There exist differences among the dispensable amino acids to act as effective nitrogen sources in humans. Glycine, a dispensable amino acid is conditionally indispensable in later stages of human pregnancy.

SUMMARY

The so-called 'dispensable' amino acids are quantitatively nearly 75% of the daily protein needs in humans. In certain life-stages and diseases, there is a dietary demand for the dispensable amino acids. Future well-designed studies are required to identify the dietary demand for these amino acids, which will certainly be useful for dietary management in specific diseases and to maintain health across all life-stages.

Comparison of Multiple Bioactive Constituents in the Corolla and Other Parts of Abelmoschus manihot

Abelmoschus manihot (L.) Medic (AM), called Huangshukui in Chinese, is a widely used medicinal plant. Each part of AM has medicinal value, including Abelmoschi Radix (AR), Abelmoschi Herba (AH), Abelmoschi Folium (AF), Abelmoschi Corolla (AC), and Abelmoschi Semen (AS). However, only AC is documented in the Chinese Pharmacopoeia. In order to investigate whether there is any difference between AC and the other parts of AM, an analytical method based on ultra-fast performance liquid chromatography coupled with triple quadrupole-linear ion trap mass spectrometry (UFLC-QTRAP-MS/MS) was established for the simultaneous determination of 35 constituents in different parts of AM. Moreover, principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to classify and evaluate the different parts of AM based on the content of the 35 constituents. The total contents of the 35 constituents in AC were significantly higher than in the other parts of AM and the results revealed significant differences between AC and the other parts of AM. Eight constituents were remarkably related to the sample classifications. This research does not just provide the basic information for revealing the distribution patterns in different parts of AM from the same origin, but also complements some of the scientific data for the comprehensive quality evaluation of AC.

Low Protein Diets and Plant-Based Low Protein Diets: Do They Meet Protein Requirements of Patients with Chronic Kidney Disease?

A low protein diet (LPD) has historically been used to delay uremic symptoms and decrease nitrogen (N)-derived catabolic products in patients with chronic kidney disease (CKD). In recent years it has become evident that nutritional intervention is a necessary approach to prevent wasting and reduce CKD complications and disease progression. While a 0.6 g/kg, high biological value protein-based LPD has been used for years, recent observational studies suggest that plant-derived LPDs are a better approach to nutritional treatment of CKD. However, plant proteins are less anabolic than animal proteins and amino acids contained in plant proteins may be in part oxidized; thus, they may not completely be used for protein synthesis. In this review, we evaluate the role of LPDs and plant-based LPDs on maintaining skeletal muscle mass in patients with CKD and examine different nutritional approaches for improving the anabolic properties of plant proteins when used in protein-restricted diets.

Histidine Metabolism and Function

Histidine is a dietary essential amino acid because it cannot be synthesized in humans. The WHO/FAO requirement for adults for histidine is 10 mg · kg body weight-1 · d-1. Histidine is required for synthesis of proteins. It plays particularly important roles in the active site of enzymes, such as serine proteases (e.g., trypsin) where it is a member of the catalytic triad. Excess histidine may be converted to trans-urocanate by histidine ammonia lyase (histidase) in liver and skin. UV light in skin converts the trans form to cis-urocanate which plays an important protective role in skin. Liver is capable of complete catabolism of histidine by a pathway which requires folic acid for the last step, in which glutamate formiminotransferase converts the intermediate N-formiminoglutamate to glutamate, 5,10 methenyl-tetrahydrofolate, and ammonia. Inborn errors have been recognized in all of the catabolic enzymes of histidine. Histidine is required as a precursor of carnosine in human muscle and parts of the brain where carnosine appears to play an important role as a buffer and antioxidant. It is synthesized in the tissue by carnosine synthase from histidine and β-alanine, at the expense of ATP hydrolysis. Histidine can be decarboxylated to histamine by histidine decarboxylase. This reaction occurs in the enterochromaffin-like cells of the stomach, in the mast cells of the immune system, and in various regions of the brain where histamine may serve as a neurotransmitter.

Glycine, a Dispensable Amino Acid, Is Conditionally Indispensable in Late Stages of Human Pregnancy

BACKGROUND

Recently, we showed that there are higher protein, lysine, and phenylalanine requirements in late stages of pregnancy compared with early stages. Animal studies have suggested an increased dietary need for specific dispensable amino acids in pregnancy; whether such a need exists in human pregnancies is unknown.

OBJECTIVE

The objective of the current study was to examine whether healthy pregnant women at midgestation (20-29 wk) and late gestation (30-40 wk) have a dietary demand for glycine, a dispensable amino acid, using the indicator amino acid oxidation method and measurement of plasma 5-oxoproline concentrations.

METHODS

Seventeen healthy women (aged 26-36 y) randomly received different test glycine intakes (range: 5-100 mg·kg-1·d-1) during each study day in midgestation (∼26 wk, n = 17 observations in 9 women) and late gestation (∼35 wk, n = 19 observations in 8 women). Diets were isocaloric with energy at 1.7 × resting energy expenditure. Protein was given as a crystalline amino acid mixture based on egg protein composition at current estimated average requirement (EAR; 0.88 g·kg-1·d-1). Breath samples were collected at baseline and isotopic steady state to measure oxidation of L-[1-13C]phenylalanine to 13CO2 (F13CO2). Plasma was collected at the sixth hour of the study day. Linear regression crossover analysis and simple linear regression were used to assess responses in F13CO2 and plasma 5-oxoproline concentrations to different glycine intakes.

RESULTS

No statistically significant responses were observed in midgestation. However, in late gestation, lower glycine intakes resulted in higher rates of F13CO2 (suggesting low protein synthesis) with a breakpoint for phenylalanine oxidation at >37 mg glycine·kg-1·d-1 and higher plasma 5-oxoproline (suggesting low glycine availability) with a breakpoint >27 mg glycine·kg-1·d-1.

CONCLUSIONS

The findings suggest that glycine should be considered a "conditionally" indispensable amino acid during late gestation, especially when protein intakes are at 0.88 g·kg-1·d-1, the current EAR. This trial was registered at clinicaltrials.gov as NCT02149953.