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Measurement of True Indispensable Amino Acid Digestibility by the Dual Isotope Tracer Technique: A Methodological Review. J Nutr 2023; 153:17-26. [PMID: 36913451 DOI: 10.1016/j.tjnut.2022.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/30/2022] [Accepted: 11/09/2022] [Indexed: 12/24/2022] Open
Abstract
The digestible indispensable amino acid score uses ileal digestibility of each indispensable amino acid (IAA) of a dietary protein to calculate its protein quality. However, true ileal digestibility, which is the exclusive sum of digestion and absorption of a dietary protein up to the terminal ileum, is difficult to measure in humans. It is traditionally measured using invasive oro-ileal balance methods but can be confounded by endogenous secreted protein in the intestinal lumen, although the use of intrinsically labeled protein corrects for this. A recent, minimally invasive dual isotope tracer technique is now available to measure true IAA digestibility of dietary protein sources. This method involves simultaneous ingestion of 2 intrinsically but differently (stable) isotopically labeled proteins, a (2H or 15N-labeled) test protein and (13C-labeled) reference protein whose true IAA digestibility is known. Using a plateau-feeding protocol, the true IAA digestibility is determined by comparing the steady state ratio of blood to meal test protein IAA enrichment to the similar reference protein IAA ratio. The use of intrinsically labeled protein also distinguishes between IAA of endogenous and dietary origin. The collection of blood samples makes this method minimally invasive. As the α-15N and α-2H atoms of AAs of the intrinsically labeled protein are prone to label loss because of transamination, underestimation of digestibility, appropriate correction factors need to be employed when using 15N or 2H labeled test protein. The true IAA digestibility values of highly digestible animal protein by the dual isotope tracer technique are comparable to that measured by direct oro-ileal balance measurements, but no data are yet available for proteins with lower digestibility. A major advantage is that the minimally invasive method allows for true IAA digestibility measurement in humans across different age groups and physiological conditions.
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Sneak-peek into iron deficiency anemia in India: The need for food-based interventions and enhancing iron bioavailability. Food Res Int 2022; 162:111927. [DOI: 10.1016/j.foodres.2022.111927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 09/02/2022] [Accepted: 09/08/2022] [Indexed: 11/22/2022]
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Shumoy H, Raes K. Dissecting the facts about the impact of contaminant iron in human nutrition: A review. Trends Food Sci Technol 2021. [DOI: 10.1016/j.tifs.2021.08.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Glahn RP, Noh H. Redefining Bean Iron Biofortification: A Review of the Evidence for Moving to a High Fe Bioavailability Approach. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021. [DOI: 10.3389/fsufs.2021.682130] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Iron biofortification of the common bean (Phaseolus vulgaris) commenced in earnest ~18 years ago. Based on knowledge at the time, the biofortification approach for beans was simply to breed for increased Fe concentration based on 3 major assumptions: (1) The average bean Fe concentration is ~50 μg/g; (2) Higher Fe concentration results in more bioavailable Fe delivered for absorption; (3) Breeding for high Fe concentration is a trait that can be achieved through traditional breeding and is sustainable once a high Fe bean sample is released to farmers. Current research indicates that the assumptions of the high Fe breeding approach are not met in countries of East Africa, a major focus area of bean Fe biofortification. Thus, there is a need to redefine bean Fe biofortification. For assumption 1, recent research indicates that the average bean Fe concentration in East Africa is 71 μg/g, thus about 20 μg/g higher than the assumed value. For assumption 2, recent studies demonstrate that for beans higher Fe concentration does not always equate to more Fe absorption. Finally, for assumption 3, studies show a strong environment and genotype by environment effect on Fe concentration, thus making it difficult to develop and sustain high Fe concentrations. This paper provides an examination of the available evidence related to the above assumptions, and offers an alternative approach utilizing tools that focus on Fe bioavailability to redefine Fe biofortification of the common bean.
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Zhang YY, Stockmann R, Ng K, Ajlouni S. Opportunities for plant-derived enhancers for iron, zinc, and calcium bioavailability: A review. Compr Rev Food Sci Food Saf 2020; 20:652-685. [PMID: 33443794 DOI: 10.1111/1541-4337.12669] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/31/2022]
Abstract
Understanding of the mechanism of interactions between dietary elements, their salts, and complexing/binding ligands is vital to manage both deficiency and toxicity associated with essential element bioavailability. Numerous mineral ligands are found in both animal and plant foods and are known to exert bioactivity via element chelation resulting in modulation of antioxidant capacity or micobiome metabolism among other physiological outcomes. However, little is explored in the context of dietary mineral ligands and element bioavailability enhancement, particularly with respect to ligands from plant-derived food sources. This review highlights a novel perspective to consider various plant macro/micronutrients as prospective bioavailability enhancing ligands of three essential elements (Fe, Zn, and Ca). We also delineate the molecular mechanisms of the ligand-binding interactions underlying mineral bioaccessibility at the luminal level. We conclude that despite current understandings of some of the structure-activity relationships associated with strong mineral-ligand binding, the physiological links between ligands as element carriers and uptake at targeted sites throughout the gastrointestinal (GI) tract still require more research. The binding behavior of potential ligands in the human diet should be further elucidated and validated using pharmacokinetic approaches and GI models.
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Affiliation(s)
- Yianna Y Zhang
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia.,CSIRO Agriculture & Food, Werribee, VIC, Australia
| | | | - Ken Ng
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Said Ajlouni
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
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Glahn R, Tako E, Hart J, Haas J, Lung'aho M, Beebe S. Iron Bioavailability Studies of the First Generation of Iron-Biofortified Beans Released in Rwanda. Nutrients 2017; 9:nu9070787. [PMID: 28754026 PMCID: PMC5537901 DOI: 10.3390/nu9070787] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 07/12/2017] [Accepted: 07/17/2017] [Indexed: 12/21/2022] Open
Abstract
This paper represents a series of in vitro iron (Fe) bioavailability experiments, Fe content analysis and polyphenolic profile of the first generation of Fe biofortified beans (Phaseolus vulgaris) selected for human trials in Rwanda and released to farmers of that region. The objective of the present study was to demonstrate how the Caco-2 cell bioassay for Fe bioavailability can be utilized to assess the nutritional quality of Fe in such varieties and how they may interact with diets and meal plans of experimental studies. Furthermore, experiments were also conducted to directly compare this in vitro approach with specific human absorption studies of these Fe biofortified beans. The results show that other foods consumed with beans, such as rice, can negatively affect Fe bioavailability whereas potato may enhance the Fe absorption when consumed with beans. The results also suggest that the extrinsic labelling approach to measuring human Fe absorption can be flawed and thus provide misleading information. Overall, the results provide evidence that the Caco-2 cell bioassay represents an effective approach to evaluate the nutritional quality of Fe-biofortified beans, both separate from and within a targeted diet or meal plan.
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Affiliation(s)
- Raymond Glahn
- USDA-ARS Robert Holley Center for Agriculture and Health, Ithaca, NY 14853, USA.
| | - Elad Tako
- USDA-ARS Robert Holley Center for Agriculture and Health, Ithaca, NY 14853, USA.
| | - Jonathan Hart
- USDA-ARS Robert Holley Center for Agriculture and Health, Ithaca, NY 14853, USA.
| | - Jere Haas
- Division of Nutritional Sciences, 220 Savage Hall, Cornell University, Ithaca, NY 14853, USA.
| | - Mercy Lung'aho
- International Center for Tropical Agriculture (CIAT), Regional Office for Africa, P.O. Box 823-00621, Nairobi 00100, Kenya.
| | - Steve Beebe
- International Center for Tropical Agriculture (CIAT), Km 17, Recta Cali-Palmira CP 763537, Apartado Aéreo 6713, Cali, Colombia.
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Glahn RP, Cheng Z, Giri S. Extrinsic Labeling of Staple Food Crops with Isotopic Iron Does Not Consistently Result in Full Equilibration: Revisiting the Methodology. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:9621-9628. [PMID: 26456842 DOI: 10.1021/acs.jafc.5b03926] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Extrinsic isotopic labeling of food Fe has been used for over 50 years to measure Fe absorption. This method assumes that complete equilibration occurs between the extrinsic and the intrinsic Fe prior to intestinal absorption. The present study tested this assumption via in vitro digestion of varieties of maize, white beans, black beans, red beans, and lentils. Prior to digestion, foods were extrinsically labeled with (58)Fe at concentrations of 1, 10, 50, and 100% of the intrinsic (56)Fe. Following an established in vitro digestion protocol, the digest was centrifuged and the Fe solubilities of the extrinsic (58)Fe and the intrinsic (56)Fe were compared as a measure of extrinsic/intrinsic equilibration. In the beans, significantly more of the extrinsic Fe (up to 2-3 times, p < 0.001) partitioned into the supernatant. The effect varied depending upon the seed coat color, the harvest, and the concentration of the extrinsic Fe. For lentils and maize the extrinsic Fe tended to partition into the insoluble fraction and also varied depending on variety and harvest. There was no crop that consistently demonstrated full equilibration of the extrinsic Fe with the intrinsic Fe. These observations challenge the accuracy of Fe absorption studies in which isotopic extrinsic Fe was used to evaluate Fe absorption and bioavailability.
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Affiliation(s)
- Raymond P Glahn
- Robert Holley Center for Agriculture and Health, Agricultural Research Service, U.S. Department of Agriculture , 538 Tower Road, Ithaca, New York 14853, United States
| | - Zhiqiang Cheng
- Department of Food Science, Cornell University , Stocking Hall, 411 Tower Road, Ithaca, New York 14853, United States
| | - Shree Giri
- Department of Food Science, Cornell University , Stocking Hall, 411 Tower Road, Ithaca, New York 14853, United States
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Flores SR, Dobbs J, Dunn MA. Mineral nutrient content and iron bioavailability in common and Hawaiian seaweeds assessed by an in vitro digestion/Caco-2 cell model. J Food Compost Anal 2015. [DOI: 10.1016/j.jfca.2015.06.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Glahn RP. Iron biofortification and revisiting the accuracy of extrinsic labeling in studies of iron absorption. J Nutr 2015; 145:1025-6. [PMID: 25934664 DOI: 10.3945/jn.114.204529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Raymond P Glahn
- From the USDA Agricultural Research Service and Robert Holley Center for Agriculture and Health, Ithaca, NY (RPG, e-mail: )
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