Agnès Marsset-Baglieri

Sequential release of milk protein–derived bioactive peptides in the jejunum in healthy humans

BACKGROUND The digestive hydrolysis of dietary proteins leads to the release of peptides in the intestinal tract, where they may exert a variety of functions, but their characterization and quantification are difficult. OBJECTIVES We aimed to characterize and determine kinetics of the formation of peptides present in the jejunum of humans who ingested casein or whey proteins by using mass spectrometry and to look for and quantify bioactive peptides. DESIGN Subjects were equipped with a double-lumen nasogastric tube that migrated to the proximal jejunum. A sample collection was performed for 6 h after the ingestion of 30 g (15)N-labeled casein (n = 7) or whey proteins (WPs; n = 6). Nitrogen flow rates were measured, and peptides were identified by using mass spectrometry. RESULTS After casein ingestion, medium-size peptides (750-1050 kDa) were released during 6 h, whereas larger peptides (1050-1800 kDa) were released from WPs in the first 3 h. A total of 356 and 146 peptides were detected and sequenced in the jejunum after casein and WP ingestion, respectively. β-casein was the most important precursor of peptides, including bioactive peptides with various activities. The amounts of β-casomorphins (β-casein 57-, 58-, 59-, and 60-66) and β-casein 108-113 released on the postprandial window were sufficient to elicit the biological action of these peptides (ie, opioid and antihypertensive, respectively). CONCLUSIONS Clear evidence is shown of the presence of bioactive peptides in the jejunum of healthy humans who ingested casein. Our findings raise the question about the physiologic conditions under which these peptides can express their bioactivity in humans. This trial was registered at clinicaltrials.gov as NCT00862329.

Characterization of the Three-Factor Eating Questionnaire scores of a young French cohort.

The aims of our study were to characterize the psychological dimensions of eating behaviour of young French adults as measured by the Three Factor Eating Questionnaire (TFEQ) and to analyze the association between the 3 TFEQ mean scores (main scales and subscales) and gender, Body Mass Index (BMI) and socio-demographic data in this population. An online TFEQ questionnaire was used with a nationally representative sample of 1000 young French people (aged 20-39yrs). The average scores were 6.3±0.1 (sem) for dietary restraint, 6.0±0.1 for disinhibition and 5.0±0.1 for hunger. Compared to the limit commonly used in human food studies, young French adults were characterized by low restraint and low disinhibition levels. There was a significant gender effect on both restraint and disinhibition scores, with women showing significantly higher scores than men. Concerning the link between TFEQ scores and BMI, there was a significant effect of the BMI category on cognitive restraint, disinhibition and hunger. Disinhibition was the factor most strongly associated to BMI, independently of gender. Our results highlight both the importance of taking into account not only disinhibition but also cognitive restraint and the usefulness of subscales when studying eating behaviour and its link to body weight. We characterize the eating behaviour of a French cohort with criteria often chosen for healthy volunteers in human food studies. Consequently, we suggest new TFEQ limits (6 for cognitive restraint and disinhibition, 5 for hunger) lower than those traditionally used for this category of the population in clinical food studies.

High True Ileal Digestibility but Not Postprandial Utilization of Nitrogen from Bovine Meat Protein in Humans Is Moderately Decreased by High-Temperature, Long-Duration Cooking

BACKGROUND Meat protein digestibility can be impaired because of indigestible protein aggregates that form during cooking. When the aggregates are subsequently fermented by the microbiota, they can generate potentially harmful compounds for the colonic mucosa. OBJECTIVE This study evaluated the quantity of bovine meat protein escaping digestion in the human small intestine and the metabolic fate of exogenous nitrogen, depending on cooking processes. METHODS Sixteen volunteers (5 women and 11 men; aged 28 ± 8 y) were equipped with a double lumen intestinal tube positioned at the ileal level. They received a test meal exclusively composed of 120 g of intrinsically (15)N-labeled bovine meat, cooked either at 55°C for 5 min (n = 8) or at 90°C for 30 min (n = 8). Ileal effluents and blood and urine samples were collected over an 8-h period after the meal ingestion, and (15)N enrichments were measured to assess the digestibility of meat proteins and the transfer of dietary nitrogen into the metabolic pools. RESULTS Proteins tended to be less digestible for the meat cooked at 90°C for 30 min than at 55°C for 5 min (90.1% ± 2.1% vs. 94.1% ± 0.7% of ingested N; P = 0.08). However, the particle number and size in ileal digesta did not differ between groups. The appearance of variable amounts of intact fibers was observed by microscopy. The kinetics of (15)N appearance in plasma proteins, amino acids, and urea were similar between groups. The amount of exogenous nitrogen lost through deamination did not differ between groups (21.2% ± 0.8% of ingested N). CONCLUSIONS Cooking bovine meat at a high temperature for a long time can moderately decrease protein digestibility compared with cooking at a lower temperature for a short time and does not affect postprandial exogenous protein metabolism in young adults. The study was registered at www.clinicaltrials.gov as NCT01685307.