Jejunal Casein Feeding Is Followed by More Rapid Protein Digestion and Amino Acid Absorption When Compared with Gastric Feeding in Healthy Young Men

Nasogastric bolus administration of a protein-rich drink augments insulinaemia and aminoacidaemia but not whole-body protein turnover or muscle protein synthesis versus oral administration

Nasogastric feeding of protein-rich liquids is a nutritional support therapy that attenuates muscle mass loss. However, whether administration via a nasogastric tube per se augments whole-body or muscle protein anabolism compared with oral administration is unknown. Healthy participants were administered a protein-rich drink (225 ml containing 21 g protein) orally (ORAL; n=13; age 21 ± 1 year; BMI 22.2 ± 0.6 kg·m-2) or via a nasogastric tube (NG; n=13; age 21 ± 1 yr; BMI 23.9 ± 0.9 kg·m-2) in a parallel group design, balanced for sex. L-[ring-2H5]-phenylalanine and L-[3,3-2H2]-tyrosine were infused to measure postabsorptive and postprandial whole-body protein turnover. Skeletal muscle biopsies were collected at -120, 0, 120 and 300 min relative to drink administration to quantify temporal myofibrillar fractional synthetic rates (myoFSR). Drink administration increased serum insulin and plasma amino acid concentrations, and to a greater extent and duration in NG versus ORAL (all interactions P<0.05). Drink administration increased whole-body protein synthesis (P<0.01), suppressed protein breakdown (P<0.001), and created positive net protein balance (P<0.001), but to a similar degree in ORAL and NG (interactions P>0.05). Drink administration increased myoFSR from the postabsorptive state (P<0.01), regardless of route of administration in ORAL and in NG (interaction P>0.05). Nasogastric bolus administration of a protein-rich drink induces insulinaemia and aminoacidaemia to a greater extent than oral administration, but the postprandial increase in whole-body protein turnover and muscle protein synthesis was equivalent between administration routes. Nasogastric administration is a potent intervention to increase postprandial amino acid availability. Future work should assess its utility in overcoming impaired sensitivity to protein feeding, such as that seen in ageing, disuse, and critical care.

The impact of advanced age on gastrointestinal characteristics that are relevant to oral drug absorption: An AGePOP review

The purpose of this review is to summarize the current knowledge on three physiological determinants of oral drug absorption, i.e., gastric emptying, volumes and composition of luminal fluids, and intestinal permeability, in the advanced age population, so that potential knowledge gaps and directions for further research efforts are identified. Published data on gastric emptying rates in older people are conflicting. Also, there are significant knowledge gaps, especially on gastric motility and emptying rates of drugs and of non-caloric fluids. Compared with younger adults, volumes of luminal contents seem to be slightly smaller in older people. Our understanding on the impact of advanced age on luminal physicochemical characteristics is, at best, very limited, whereas the impact of (co)morbidities and geriatric syndromes in the advanced age population has not been addressed to date. The available literature on the effect of advanced age on intestinal permeability is limited, and should be approached with caution, primarily due to the limitations of the experimental methodologies used.

Time Courses of Gastric Volume and Content after Different Types of Casein Ingestion in Healthy Men: A Randomized Crossover Study

BACKGROUND

Few studies have evaluated differences in the curd-forming ability of casein on gastric volume and content directly after ingestion in humans.

OBJECTIVES

This study evaluated the time course of gastric volume and curd conditions in the stomach after protein ingestion.

METHODS

This was an open-labeled, randomized crossover trial. Ten healthy men [age: 33.4 ± 7.3 y; BMI (kg/m²): 21.9 ± 0.9] received 350 g of 3 isonitrogenous and isocaloric protein drinks containing 30 g micellar casein (MCN), sodium caseinate (SCN), or whey protein concentrate (WPC). The gastric antrum cross-sectional area (CSA) and curd in the stomach were measured using ultrasonography within 5 h after ingestion. The differences between test foods were tested using the MIXED model and post hoc tests using Fisher's protected least significant difference.

RESULTS

The incremental AUC of the gastric antrum CSA after MCN ingestion was 1.3-fold and 1.5-fold higher than that after the ingestion of SCN and WPC, respectively (both P < 0.05), but not different between SCN and WPC. The number of participants with curds ≥20 mm with a high echogenicity clot observed in the stomach within 5 h after MCN ingestion was significantly greater than that after the ingestion of other proteins (n = 9 for MCN, n = 2 for SCN, and n = 0 for WPC; bothP < 0.01). The regression line slopes on total plasma amino acid concentration and gastric antrum CSA were significantly different between the participants with and without curds.

CONCLUSIONS

In contrast to SCN and WPC, MCN ingestion resulted in slow kinetics of gastric antrum CSA. Differences in curd formation of casein in the stomach affect gastric emptying and plasma amino acid absorption kinetics after ingestion in healthy men. This trial was registered at University Hospital Medical Information Network Clinical Trials Registry as UMIN000038388 (https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000043746).

Measuring the oral bioavailability of protein hydrolysates derived from food sources: A critical review of current bioassays

BACKGROUND

Food proteins are a source of hydrolysates with potentially useful biological attributes. Bioactive peptides from food-derived proteins are released from hydrolysates using exogenous industrial processes or endogenous intestinal enzymes. Current in vitro permeability assays have limitations in predicting the oral bioavailability (BA) of bioactive peptides in humans. There are also difficulties in relating the low blood levels of food-derived bioactive peptides detected in preclinical in vivo models to pharmacodynamic read-outs relevant for humans.

SCOPE AND APPROACH

In this review, we describe in vitro assays of digestion, permeation, and metabolism as indirect predictors of the potential oral BA of hydrolysates and their constituent bioactive peptides. We discuss the relationship between industrial hydrolysis processes and the oral BA of hydrolysates and their peptide by-products.

KEY FINDINGS

Hydrolysates are challenging for analytical detection methods due to capacity for enzymatic generation of peptides with novel sequences and also new modifications of these peptides during digestion. Mass spectrometry and peptidomics can improve the capacity to detect individual peptides released from complex hydrolysates in biological milieu.

Using naso- and oro-intestinal catheters in physiological research for intestinal delivery and sampling in vivo: practical and technical aspects to be considered

Intestinal catheters have been used for decades in human nutrition, physiology, pharmacokinetics, and gut microbiome research, facilitating the delivery of compounds directly into the intestinal lumen or the aspiration of intestinal fluids in human subjects. Such research provides insights about (local) dynamic metabolic and other intestinal luminal processes, but working with catheters might pose challenges to biomedical researchers and clinicians. Here, we provide an overview of practical and technical aspects of applying naso- and oro-intestinal catheters for delivery of compounds and sampling luminal fluids from the jejunum, ileum, and colon in vivo. The recent literature was extensively reviewed, and combined with experiences and insights we gained through our own clinical trials. We included 60 studies that involved a total of 720 healthy subjects and 42 patients. Most of the studies investigated multiple intestinal regions (24 studies), followed by studies investigating only the jejunum (21 studies), ileum (13 studies), or colon (2 studies). The ileum and colon used to be relatively inaccessible regions in vivo. Custom-made state-of-the-art catheters are available with numerous options for the design, such as multiple lumina, side holes, and inflatable balloons for catheter progression or isolation of intestinal segments. These allow for multiple controlled sampling and compound delivery options in different intestinal regions. Intestinal catheters were often used for delivery (23 studies), sampling (10 studies), or both (27 studies). Sampling speed decreased with increasing distance from the sampling syringe to the specific intestinal segment (i.e., speed highest in duodenum, lowest in ileum/colon). No serious adverse events were reported in the literature, and a dropout rate of around 10% was found for these types of studies. This review is highly relevant for researchers who are active in various research areas and want to expand their research with the use of intestinal catheters in humans in vivo.

Enteral nutrition for severe malnutrition Crohn's disease patient: Case report

INTRODUCTION

Crohn's disease (CD) is a chronic systemic inflammatory disease with indefinite remission and relapse cycles, which can result in a high incidence rate of malnutrition. There has been increasing clinical interest in enteral nutrition (EN) as an adjunct treatment for CD. This report aims to present a case of a severely malnourished CD patient given EN support in combination with conventional infliximab (IFX) treatment.

PATIENT CONCERNS

A 42-year-old CD patient with severe malnutrition. She once weighted 27.5 kg (BMI 11.4 kg/m) with hyponatremia, which may cause sudden death at any time.

DIAGNOSIS

In this study, the diagnosis of CD made by our gastroenterologist was based on integrating patient symptoms, radiologic findings, and biopsy results. The patient had no differential diagnosis.

INTERVENTIONS

The patient received EN support and actively followed up for more than 2 years. The patient also received IFX treatment and four surgeries on an as-needed basis to manage her symptoms.

OUTCOMES

The patient's inflammation and symptoms were finally improved by a combination of enteral nutrition and IFX, and her body weight increased to 44 kg.

CONCLUSION

The jejunal feeding tube was the starting point of her weight gain and inflammation reduction, which allowed her adequate energy. EN may be a potential complementary therapeutic strategy to manage clinical symptoms of CD and improve severe malnutrition.

Jejunal feeding is followed by a greater rise in plasma cholecystokinin, peptide YY, glucagon-like peptide 1, and glucagon-like peptide 2 concentrations compared with gastric feeding in vivo in humans: a randomized trial

BACKGROUND

Jejunal feeding is preferred instead of gastric feeding in patients who are intolerant to gastric feeding or at risk of aspiration. However, the impact of gastric feeding compared with that of jejunal feeding on postprandial circulating plasma glucose and amino acid concentrations and the associated endocrine response in vivo in humans remains largely unexplored.

OBJECTIVE

We compared the impact of administering enteral nutrition as either gastric feeding or jejunal feeding on endocrine responses in vivo in humans.

DESIGN

In a randomized, crossover study design, 12 healthy young men (mean ± SD age: 21 ± 2 y) received continuous enteral nutrition that contained noncoagulating proteins for 12 h via a nasogastric tube or a nasojejunal tube placed 30-40 cm distal to the ligament of Treitz. Blood samples were collected during the 12-h postprandial period to assess the rise in plasma glucose, amino acid, and gastrointestinal hormone concentrations.

RESULTS

No differences were observed in the postprandial rise in circulating plasma amino acid and glucose concentrations between regimens. Jejunal feeding resulted in higher peak plasma insulin concentrations than did gastric feeding (392 ± 53 compared with 326 ± 54 pmol/L, respectively; P < 0.05). The postprandial rise in plasma cholecystokinin, peptide YY (PYY), glucagon-like peptide 1 (GLP-1), and glucagon-like peptide 2 (GLP-2) concentrations was greater after jejunal feeding than after gastric feeding, with higher peak concentrations and a greater postprandial incremental AUC for GLP-1 and cholecystokinin (all P < 0.05). Plasma ghrelin concentrations did not differ between regimens.

CONCLUSIONS

Enteral nutrition with gastric or jejunal feeding in healthy young men results in similar postprandial plasma amino acid and glucose concentrations. However, the endocrine response differs substantially, with higher peak plasma cholecystokinin, PYY, GLP-1, and GLP-2 concentrations being attained after jejunal feeding. This effect may result in an improved anabolic response, greater insulin sensitivity, and an improved intestinotropic effect. Nevertheless, it may also lead to delayed gastric emptying. This trial was registered at trialregister.nl as NTR2801.