scholarly journals Methodological considerations in measuring human calcium absorption: relevance to study the effects of inulin-type fructans

2005 ◽  
Vol 93 (S1) ◽  
pp. S105-S110 ◽  
Author(s):  
Ian J. Griffin ◽  
Steven A. Abrams
Keyword(s):  
Calcium Absorption ◽  
Plasma Samples ◽  
Mass Balances ◽  
Tracer Method ◽  
Dual Isotope ◽  
Isotope Tracer ◽  
Advantages And Disadvantages ◽  
Isotopic Methods ◽  
Methodological Considerations ◽  
Isotope Tracer Method

During the last 50 years, a variety of methods have been developed to estimate Ca absorption in man. Mass balances were initially used, but these were unable to accurately measure fractional Ca absorption because they cannot distinguish unabsorbed dietary Ca from endogenous faecal Ca excretion (excretion of previously absorbed Ca back into the gut). A number of isotopic methods have been developed that can measure true fractional Ca absorption, employing radioisotopes, stable isotopes, or both. Different methods involve collection of urine, faecal or plasma samples. Of the currently available methods, the dual isotope tracer method with a timed urine collection is probably the most precise and reliable. It is also relatively straightforward to carry out and avoids the need for a faecal collection. The purpose of the present paper is to discuss the general advantages and disadvantages of the different methods of Ca absorption. In addition, the limitations the different methods have in examining the possible effects of non-digestible oligosaccharides on Ca absorption will be discussed.

A coupled isotope tracer method to characterize input water to lakes

2008 ◽  
Vol 350 (1-2) ◽  
pp. 1-13 ◽  
Author(s):  
Yi Yi ◽  
Bronwyn E. Brock ◽  
Matthew D. Falcone ◽  
Brent B. Wolfe ◽  
Thomas W.D. Edwards
Keyword(s):  
Tracer Method ◽  
Isotope Tracer ◽  
Isotope Tracer Method

scholarly journals Ileal digestibility of intrinsically labeled hen's egg and meat protein determined with the dual stable isotope tracer method in Indian adults

2018 ◽  
Vol 108 (5) ◽  
pp. 980-987 ◽  
Author(s):  
Sindhu Kashyap ◽  
Nirupama Shivakumar ◽  
Aneesia Varkey ◽  
Rajendran Duraisamy ◽  
Tinku Thomas ◽  
...  
Keyword(s):  
Amino Acid ◽  
Tracer Method ◽  
Dual Isotope ◽  
Ileal Digestibility ◽  
Egg White Protein ◽  
Meat Protein ◽  
Isotope Tracer ◽  
Hen’S Egg ◽  
The Mean ◽  
Cooked Meat

ABSTRACTBackgroundProtein quality assessment through the Digestible Indispensable Amino Acid Score requires accurate measurements of true ileal protein and amino acid digestibility, for which a dual isotope technique was recently developed. However, the ileal digestibility of indispensable amino acids (IAA) in humans from high-quality proteins is not well known.ObjectiveThe aim of this study was to intrinsically label hen's egg and meat protein by the use of uniformly 2H-labeled amino acids, and to measure their true ileal indispensable amino acid (IAA) digestibility via the dual isotope method in humans.Design2H-labeled lyophilized boiled egg white protein, whole boiled egg, and cooked meat were obtained from layer hens (BV-300) administered a uniformly 2H-labeled amino acid mix orally for 35 d with their daily feed. The ileal IAA digestibility of these proteins was determined with reference to digestibility of previously characterized [U-13C]spirulina in a dual tracer method in healthy Indian subjects whose intestinal health was measured by the plasma kynurenine-to-tryptophan (KT) ratio.ResultsAll subjects had normal KT ratios. The mean ± SD true ileal IAA digestibility of 2H-labeled egg white protein, whole boiled egg, and cooked meat was 86.3% ± 4.6%, 89.4% ± 4.5%, and 92.0% ± 2.8%, respectively. Leucine digestibility correlated with the KT ratio (r = −0.772; P = 0.009).ConclusionsUniformly 2H-labeled hen's egg and meat protein can be used to measure ileal IAA digestibility by the dual isotope tracer approach in humans. The mean IAA digestibility values for these high-quality proteins in the healthy Indians studied were similar to values obtained in earlier human and animal experiments. Leucine digestibility in these meal matrices correlated with the KT ratio, but this aspect needs further evaluation. This trial was registered at the Clinical Trials Registry of India (http://ctri.nic.in) as CTRI/2018/03/012265.

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