Amino acid intake and plasma concentrations and their interplay with gut microbiota in vegans and omnivores in Germany

Purpose It has been estimated that most vegans meet the total protein requirements, but whether this is also true for individual essential amino acids (AAs) is unclear. Furthermore, a shift in protein intake is suggested to alter microbiota composition, but this association is unknown in terms of veganism or individual AAs. This cross-sectional study compared vegans and omnivores regarding dietary intake and plasma concentration of AAs. The prevalence of insufficient intake of essential AAs among vegans was determined using estimated average requirements (EAR) of WHO. Moreover, correlations between AAs intake and gut microbiota were investigated. Methods Data of 36 vegans and 36 omnivores (30–60 years) were analysed. AA intake, AA plasma concentrations and gut microbiota were ascertained by three-day weighed food protocols, gas/liquid chromatography-tandem mass spectrometry and 16S rRNA sequencing, respectively. Results At almost the same energy intake, the intake of 9 AAs in vegans was significantly lower than in omnivores, with median differences of − 27.0% to − 51.9%. However, only one female vegan showed total protein and lysine intake below the EAR. Vegans showed lower lysine (− 25.0%), but higher glycine (+ 25.4%) and glutamate (+ 13.1%) plasma concentrations than omnivores. Correlation patterns between AA intake and bacterial microbiota differed between vegans and omnivores. In vegans 19 species and in omnivores 5 species showed correlations with AA intake. Conclusion Vegans consumed apparently sufficient but lower AAs than omnivores. In addition, the different AAs intake seems to influence the microbiota composition. The use of short-term dietary data without considering usual intake limits these findings.

Estimating Amino Acid Requirements in Real-Time for Precision-Fed Pigs: The Challenge of Variability among Individuals

This study aimed to measure protein deposition (PD) in pigs fed with daily tailored diets where either dietary lysine (Lys) or threonine (Thr) were provided at independent levels (ignoring an ideal ratio). A total of 95 growing pigs (35 kg body weight (BW)) with electronic ear tags granting them access to automatic feeders were randomly assigned to treatments. The setup was an unbalanced 2 × 5 factorial arrangement with Lys and Thr provided at five levels (i.e., 60%, 80%, 100%, 120%, and 140% of the estimated individual requirements of Lys and Thr), resulting in 25 treatments for 21 days. The observed PD variation to Lys and Thr provisions was large, with Lys and Thr intake explaining only 11% of the variation. Cluster analysis discriminated pigs with low (167 g/d, n = 16), medium (191 g/d, n = 38), and high (213 g/d, n = 37) PD, but with a similar amino acid intake. Differences in PD were associated with differences in nutrient efficiency of utilization. Providing Lys and Thr in a factorial mode, ignoring an ideal ratio, did not decrease the variability in PD. Future research efforts should focus on identifying and investigating the sources of interindividual variability—a necessary step before final recommendations can be made for AA in precision-fed pigs.

Refeeding Syndrome in the Neonatal Intensive Care Unit

Refeeding syndrome (RS) has not been well defined in the neonatal population, although hypophosphatemia is identified as the most common manifestation. The American Society for Parenteral and Enteral Nutrition recently provided recommendations for the prevention and management of RS in children and adults; however, specific neonatal recommendations were not provided. In an effort to provide an overview of the incidence of RS or hypophosphatemia in the neonatal population and the impact of patient-specific and nutrition factors, a review of the literature was conducted. The literature search included articles published in the English language in Medline, PubMed, and EPub between 1946 and December 2020. Relevant citations within identified articles were also reviewed. Sixteen studies representing 3688 neonates were included. There was variation in the incidence of hypophosphatemia (20%–90%), hypokalemia (8.8%–66.7%), and hypomagnesemia (1%–8.3%) between studies. There was significant variability in definitions of hypophosphatemia, patient populations (e.g., gestational age, small for gestational age status, intrauterine growth restriction), and initial nutrition between studies (i.e., initial amino acid intake, calcium and phosphate ratio), proving it difficult to identify the overall incidence of neonatal RS. Clinical outcomes associated with hypophosphatemia identified in the studies included increased duration of mechanical ventilation, development of bronchopulmonary dysplasia, and increased mortality. Vigilant monitoring of serum phosphate, potassium, and magnesium is required in the first week of life. In addition, early addition of phosphate in a 1:1 molar ratio with calcium is recommended in the first week of life for patients who are at greatest risk for RS.

Modelling Broiler Requirements for Lysine and Arginine

Six assays were conducted to investigate male and female broiler responses to standardized ileal digestible (SID) lysine (Lys) and arginine (Arg). Response data were modeled to estimate the efficiency of utilization (k) of both amino acids and adjust factorial models to predict bird intake for SID Lys and SID Arg. In each assay, 1280 Cobb 500® broilers (640 male and 640 female) were randomly assigned to one of sixteen dietary treatments with four replicates of 20 birds. Dietary treatments consisted of crescent levels of SID Lys or SID Arg based on the dilution technique. The values of k determined for each phase (1- to 14-, 15- to 28-, and 29- to 42-d-old) and sex were contrasted using linear regression with groups (sex and phase). The estimated efficiencies were 0.79 for Lys and 0.62 for Arg, which were unaffected by phase or sex. Factorial models based on body weight and weight gain (M1) and on body and feather protein weight and deposition (M2) were applied to estimate the SID Lys and Arg intake for growth. The amino acid intake based on M2 had a lower error of prediction. Broiler chickens require 94.9 and 92.9 mg/d of SID Lys and SID Arg to deposit 1 g of body protein.

Tolerable amounts of amino acids for human supplementation: summary and lessons from published peer-reviewed studies

Amino acid supplementation may be indicated to correct for insufficient amino acid intake in healthy individuals, and in specific physiological or pathophysiological situations. However, there is a concern to not supplement beyond the tolerable upper intake level (UL) by determining parameters of no-observed-adverse-effect level (NOAEL) or lowest-observed-adverse-effect level (LOAEL) for each amino acid. Since the NOAEL and LOAEL values are at least one order of magnitude different when comparing the values obtained in rats and humans, the aim of this review is to evaluate to what extent the amino acid UL measured in the rat model, when referenced to the dietary usual consumption (UC) and dietary requirement (RQ) for indispensable amino acids, may be used as an approximation of the UL in humans. This review then compares the ratios of the NOAEL or LOAEL over UC and RQ in the rat model with the same ratios calculated in humans for the nine amino acids (arginine, serine, glycine, histidine, leucine, lysine, methionine, phenylalanine, and tryptophan) for which this comparison can be done. From the calculations made, it appears that for these 9 amino acids, the calculated ratios for rats and humans, although rather different for several amino acids, remains for all of them in the same order of magnitude. For tryptophan, tyrosine, and valine, the ratios calculated in rats are markedly different according to the sex of animals, raising the view that it may be also the case in humans.