Poster Topical Area: Methods and Protocols
Location: Hall D
Poster Board Number: 689
First, to intrinsically label hen's egg and meat protein, using a low oral dose of uniformly 2H-labeled amino acid mix, and second, to measure the ileal digestibility of individual Indispensible Amino Acids (IAA) from hen's egg and muscle protein using the dual stable isotope tracer approach in humans.
Two layer hens (BV-300, 29 weeks, weight: 1.5 kg) were administered 12 mg of uniformly 2H-labeled amino acid mix orally, for 35 days. The collected eggs were processed in two ways, 1) boiled for 20 minutes with yolk and white fractions separated and then lyophilized and 2) boiled only. The hens were sacrificed; muscle was pooled and pressure-cooked for 40 minutes. Six healthy adults were studied with each test protein (2H-labeled lyophilized egg white protein, whole boiled egg and cooked meat). Subjects were administered a culturally accepted test meal in a plateau feeding protocol, for 8 hours. As a characterized standard protein, 12 mg/kg of U-13C spirulina was added to the meal. Breath and blood samples were collected at baseline and at specified time points during the protocol. Intestinal health was measured using baseline plasma kynurenine-tryptophan (KT) ratio. Meal and plasma 2H- and 13C-isotopic enrichment analyses were performed by liquid chromatography–mass spectrometry. Breath samples were analyzed for 13CO2 enrichments by isotope ratio mass spectrometry. Digestibility for each IAA was calculated as the postprandial ratio of the appearance of 2H and 13C labeled amino acids in the blood in comparison to their ratio in the test meal.
A total of 85 labeled eggs were collected, from which 156 g of dry lyophilized egg white protein was obtained. Preliminary data showed IAA ileal digestibility (mean ± SD) of 86.3 ± 4.6%, 89.4 ± 4.5% and 92.0 ± 2.8% for 2H-labeled egg white protein, whole boiled egg and cooked meat respectively. Leucine digestibility correlated with the KT ratio (r=-0.772; p=0.009).
The study demonstrates the use of uniformly 2H-labeled hen's egg and meat protein in measuring ileal IAA digestibility by the dual isotope tracer approach, in humans. The IAA digestibility values from this study could inform protein quality assessment by DIAAS approach. Leucine digestibility in these meal matrixes correlated with the KT ratio, but this needs further evaluation
St. John's National Academy of Health Sciences
Bangalore, Karnataka, India