Amino Acid Bioavilability of Fava Beans

The objective is to determine the nutritional quality of protein from favabean in healthy humans, especially in terms of amino acid digestibility. Ileal digestibility is determined in ileal digesta collected postprandially with a naso-ileal tube. The favabeans are intrinsically labelled in 15N in order to track dietary nitrogen and amino acids in the samples.

Ethical and regulatory aspects:

The protocole was submitted to the Ethical Committee for approval and to the French Agency of Drugs and Health for administrative authorization. The personal data management will be in accordance with the regulation on personal data protection ( " regulation n° 2018-493 du 20 juin 2018").

Meal:

The meal will consist in 250 g of cooked and peeled favabean, to provide 20 g protein. Sensory tests will be realized to optimize the organoleptic properties of the meal. 15N labelled bean will be boiled in water with salt. On the morning of the experiment, the portion of fava bean will be warmed up.

Volunteers:

Eight subjects will be included in the study. The investigators plan to recruit around 16 volunteers to accommodate for the usual 50% dropouts.

One week before the experiment, the volunteers will follow a standard diet adapted to their body weight to control their protein intake (1.3 g protein/kg body weight). They will be ask to consume one to 3 portions of favabean in the week.

The volunteers will arrive at the Human Nutrition Research Centre of Avicenne Hospital on the morning before the day of the experiment. They will be equipped with a double lumen intestinal tube that will be allowed to progress through the intestinal tract for 24h. One of the lumen is radio opaque and serves to perfuse a non-absorbable maker in the intestine (slow marker method). The other lumen is dedicated to the continuous aspiration of the effluents, 15 cm below the perfusion site. The measurement of the non-absorbable marker in the effluents allows the determination of the effluent flow rate.

On the day of the experiment, the position of the tube will be checked by radiography to verify its location at the terminal ileum. A catheter will be inserted in the forearm vein for blood sampling. The perfusion of the non-absorbable marker, PEG-4000 (20g/l), will start at a flow rate of 1ml/min. The intestinal flow and the basal ileal sample will be collected during 30 min. Basal plasma sample will be sampled.

Then, at t=0, the volunteers will drink the test-meal. Until t=8h, intestinal content will be continuously collected by aspiration and pooled every 30 minutes. Blood will be sampled every 30 minutes during 4h and hourly thereafter. The urine will be collected every 2 h for 8 h.

Subjects will collect stools samples at home during the 48 h after the meal. Stools will be sent to Finland.

Measurements:

In the digesta:

PEG-4000 by turbidimetric method, total N and 15N enrichment by EA-IRMS, amino acid concentrations by UPLC (after acid hydrolysis HCl 6N at 110°C for 24h), 15N amino acid enrichment by GC-c-IRMS (after purification on cation exchange resin and derivatization).

In the plasma:

Glucose, urea (colorimetric methods), insulin (ELISA), amino acid concentrations (UPLC), 15N enrichment in plasma protein, urea and free amino acids (EA-IRMS, after purification on cation exchange resin and derivatization).

In the urine:

Urea (colorimetric method) and 15N urea (EA-IRMS, after purification on cation exchange resin and derivatization).

In the stools:

Micriobial DNA.

Outcomes:

Real ileal digestibility of protein and amino acids (digestive losses), Postprandial deamination (metabolic losses), Net Postprandial Protein Utilization, Microbiota composition.