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Domellöf M, Sjöberg A. Iron - a background article for the Nordic Nutrition Recommendations 2023. Food Nutr Res 2024; 68:10451. [PMID: 38370116 PMCID: PMC10870973 DOI: 10.29219/fnr.v68.10451] [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: 06/15/2022] [Revised: 11/14/2023] [Accepted: 12/20/2023] [Indexed: 02/20/2024] Open
Abstract
Iron absorption from foods is generally lower than that of most other nutrients and is highly variable depending on individual iron status and iron bioavailability in the meal. Several large population groups in the Nordic and Baltic countries are at risk of iron deficiency, including infants, young children, menstruating females, pregnant women as well as vegetarians. Iron deficiency leads to anemia, fatigue, and limited capacity for physical activity. Of particular concern is that iron deficiency anemia in young children is associated with impaired neurodevelopment. A comprehensive literature search has been performed and summarized. New factorial calculations have been performed considering iron losses, iron absorption and iron requirements in various population groups. Recent data on iron intakes and the prevalence of iron deficiency in the Nordic countries are presented. Average requirements and tentative recommended intakes are presented for 12 different population groups. Pregnant women and those with high menstrual blood losses should consume iron-rich food and undergo screening for iron deficiency. Infants should consume iron-rich complementary foods and cow's milk should be avoided as a drink before 12 months of age and limited to < 500 mL/day in toddlers. Vegetarians should consume a diet including wholegrains, legumes, seeds, and green vegetables together with iron absorption enhancers. There is no evidence that iron intake per se increases the risk of cancer or diabetes. Iron absorption from foods is generally lower than that of most other nutrients and can vary between <2 and 50% depending on individual iron status and iron bioavailability in the meal.
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Affiliation(s)
- Magnus Domellöf
- Department of Clinical Sciences, Umeå University, Umeå, Sweden
| | - Agneta Sjöberg
- Department of Food and Nutrition and Sport Science, University of Gothenburg, Gothenburg, Sweden
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Pujol A, Sanchis P, Grases F, Masmiquel L. Phytate Intake, Health and Disease: "Let Thy Food Be Thy Medicine and Medicine Be Thy Food". Antioxidants (Basel) 2023; 12:antiox12010146. [PMID: 36671007 PMCID: PMC9855079 DOI: 10.3390/antiox12010146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023] Open
Abstract
Phytate (myo-inositol hexakisphosphate or InsP6) is the main phosphorus reservoir that is present in almost all wholegrains, legumes, and oilseeds. It is a major component of the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets. Phytate is recognized as a nutraceutical and is classified by the Food and Drug Administration (FDA) as Generally Recognized As Safe (GRAS). Phytate has been shown to be effective in treating or preventing certain diseases. Phytate has been shown to inhibit calcium salt crystallization and, therefore, to reduce vascular calcifications, calcium renal calculi and soft tissue calcifications. Moreover, the adsorption of phytate to the crystal faces can inhibit hydroxyapatite dissolution and bone resorption, thereby playing a role in the treatment/prevention of bone mass loss. Phytate has a potent antioxidation and anti-inflammatory action. It is capable of inhibiting lipid peroxidation through iron chelation, reducing iron-related free radical generation. As this has the effect of mitigating neuronal damage and loss, phytate shows promise in the treatment/prevention of neurodegenerative disease. It is reported that phytate improves lipid and carbohydrate metabolism, increases adiponectin, decreases leptin and reduces protein glycation, which is linked with macrovascular and microvascular diabetes complications. In this review, we summarize the benefits of phytate intake as seen in in vitro, animal model, epidemiological and clinical trials, and we also identify questions to answer in the future.
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Affiliation(s)
- Antelm Pujol
- Vascular and Metabolic Diseases Research Group, Endocrinology Department, Son Llàtzer University Hospital, Health Research Institute of the Balearic Islands (IdISBa), 07198 Palma de Mallorca, Spain
- Correspondence: (A.P.); (L.M.)
| | - Pilar Sanchis
- Laboratory of Renal Lithiasis Research, Deptartment of Chemistry, University of Balearic Islands, Health Research Institute of Balearic Islands, (IdISBa), 07122 Palma de Mallorca, Spain
| | - Felix Grases
- Laboratory of Renal Lithiasis Research, Deptartment of Chemistry, University of Balearic Islands, Health Research Institute of Balearic Islands, (IdISBa), 07122 Palma de Mallorca, Spain
| | - Luis Masmiquel
- Vascular and Metabolic Diseases Research Group, Endocrinology Department, Son Llàtzer University Hospital, Health Research Institute of the Balearic Islands (IdISBa), 07198 Palma de Mallorca, Spain
- Correspondence: (A.P.); (L.M.)
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Piskin E, Cianciosi D, Gulec S, Tomas M, Capanoglu E. Iron Absorption: Factors, Limitations, and Improvement Methods. ACS OMEGA 2022; 7:20441-20456. [PMID: 35755397 PMCID: PMC9219084 DOI: 10.1021/acsomega.2c01833] [Citation(s) in RCA: 74] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 05/20/2022] [Indexed: 05/04/2023]
Abstract
Iron is an essential element for human life since it participates in many functions in the human body, including oxygen transport, immunity, cell division and differentiation, and energy metabolism. Iron homeostasis is mainly controlled by intestinal absorption because iron does not have active excretory mechanisms for humans. Thus, efficient intestinal iron bioavailability is essential to reduce the risk of iron deficiency anemia. There are two forms of iron, heme and nonheme, found in foods. The average daily dietary iron intake is 10 to 15 mg in humans since only 1 to 2 mg is absorbed through the intestinal system. Nutrient-nutrient interactions may play a role in dietary intestinal iron absorption. Dietary inhibitors such as calcium, phytates, polyphenols and enhancers such as ascorbic acid and proteins mainly influence iron bioavailability. Numerous studies have been carried out for years to enhance iron bioavailability and combat iron deficiency. In addition to traditional methods, innovative techniques are being developed day by day to enhance iron bioavailability. This review will provide information about iron bioavailability, factors affecting absorption, iron deficiency, and recent studies on improving iron bioavailability.
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Affiliation(s)
- Elif Piskin
- Faculty of Engineering and Natural Sciences, Food Engineering Department, Istanbul Sabahattin Zaim University, Halkali, 34303 Istanbul, Turkey
| | - Danila Cianciosi
- Faculty of Medicine, Department of Clinical Sciences, Polytechnic University of Marche, via Pietro Ranieri, 60131 Ancona, Italy
| | - Sukru Gulec
- Molecular Nutrition and Human Physiology Laboratory, Department of Food Engineering, İzmir Institute of Technology, 35430 Urla, İzmir
| | - Merve Tomas
- Faculty of Engineering and Natural Sciences, Food Engineering Department, Istanbul Sabahattin Zaim University, Halkali, 34303 Istanbul, Turkey
| | - Esra Capanoglu
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey
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Phytic Acid and Whole Grains for Health Controversy. Nutrients 2021; 14:nu14010025. [PMID: 35010899 PMCID: PMC8746346 DOI: 10.3390/nu14010025] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 12/20/2022] Open
Abstract
Phytate (PA) serves as a phosphate storage molecule in cereals and other plant foods. In food and in the human body, PA has a high affinity to chelate Zn2+ and Fe2+, Mg2+, Ca2+, K+, Mn2+ and Cu2+. As a consequence, minerals chelated in PA are not bio-available, which is a concern for public health in conditions of poor food availability and low mineral intakes, ultimately leading to an impaired micronutrient status, growth, development and increased mortality. For low-income countries this has resulted in communications on how to reduce the content of PA in food, by appropriate at home food processing. However, claims that a reduction in PA in food by processing per definition leads to a measurable improvement in mineral status and that the consumption of grains rich in PA impairs mineral status requires nuance. Frequently observed decreases of PA and increases in soluble minerals in in vitro food digestion (increased bio-accessibility) are used to promote food benefits. However, these do not necessarily translate into an increased bioavailability and mineral status in vivo. In vitro essays have limitations, such as the absence of blood flow, hormonal responses, neural regulation, gut epithelium associated factors and the presence of microbiota, which mutually influence the in vivo effects and should be considered. In Western countries, increased consumption of whole grain foods is associated with improved health outcomes, which does not justify advice to refrain from grain-based foods because they contain PA. The present commentary aims to clarify these seemingly controversial aspects.
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Vorland CJ, Brown AW, Dawson JA, Dickinson SL, Golzarri-Arroyo L, Hannon BA, Heo M, Heymsfield SB, Jayawardene WP, Kahathuduwa CN, Keith SW, Oakes JM, Tekwe CD, Thabane L, Allison DB. Errors in the implementation, analysis, and reporting of randomization within obesity and nutrition research: a guide to their avoidance. Int J Obes (Lond) 2021; 45:2335-2346. [PMID: 34326476 PMCID: PMC8528702 DOI: 10.1038/s41366-021-00909-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 06/26/2021] [Accepted: 07/06/2021] [Indexed: 02/06/2023]
Abstract
Randomization is an important tool used to establish causal inferences in studies designed to further our understanding of questions related to obesity and nutrition. To take advantage of the inferences afforded by randomization, scientific standards must be upheld during the planning, execution, analysis, and reporting of such studies. We discuss ten errors in randomized experiments from real-world examples from the literature and outline best practices for their avoidance. These ten errors include: representing nonrandom allocation as random, failing to adequately conceal allocation, not accounting for changing allocation ratios, replacing subjects in nonrandom ways, failing to account for non-independence, drawing inferences by comparing statistical significance from within-group comparisons instead of between-groups, pooling data and breaking the randomized design, failing to account for missing data, failing to report sufficient information to understand study methods, and failing to frame the causal question as testing the randomized assignment per se. We hope that these examples will aid researchers, reviewers, journal editors, and other readers to endeavor to a high standard of scientific rigor in randomized experiments within obesity and nutrition research.
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Affiliation(s)
- Colby J Vorland
- Department of Applied Health Science, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA.
| | - Andrew W Brown
- Department of Applied Health Science, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA
| | - John A Dawson
- Department of Nutritional Sciences, Texas Tech University, Lubbock, TX, USA
| | - Stephanie L Dickinson
- Department of Epidemiology and Biostatistics, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA
| | - Lilian Golzarri-Arroyo
- Department of Epidemiology and Biostatistics, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA
| | - Bridget A Hannon
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Moonseong Heo
- Department of Public Health Sciences, Clemson University, Clemson, SC, USA
| | - Steven B Heymsfield
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, USA
| | - Wasantha P Jayawardene
- Department of Applied Health Science, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA
| | - Chanaka N Kahathuduwa
- Department of Psychiatry, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Scott W Keith
- Department of Pharmacology and Experimental Therapeutics, Division of Biostatistics, Thomas Jefferson University, Philadelphia, PA, USA
| | - J Michael Oakes
- Department of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, MN, USA
| | - Carmen D Tekwe
- Department of Epidemiology and Biostatistics, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA
| | - Lehana Thabane
- Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, ON, Canada
| | - David B Allison
- Department of Epidemiology and Biostatistics, Indiana University School of Public Health-Bloomington, Bloomington, IN, USA.
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Fairweather-Tait S, Sharp P. Iron. ADVANCES IN FOOD AND NUTRITION RESEARCH 2021; 96:219-250. [PMID: 34112354 DOI: 10.1016/bs.afnr.2021.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
Iron deficiency anemia affects approximately one-third of the world's population, and about half the cases are due to iron deficiency. The latest research on iron metabolism published in original articles and systematic reviews is described, and references to recent reviews provided. The topics include dietary sources and bioavailability, iron homeostasis, functions of iron in the body, and biomarkers of status. The consequences of iron deficiency and excess are discussed, with particular focus on vulnerable populations such as pregnant women, infants and the elderly. The newest dietary recommendations, including dietary reference values and food based dietary guidelines, are briefly summarized, followed by the latest developments in food fortification and iron supplementation.
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Affiliation(s)
| | - Paul Sharp
- Department of Nutritional Sciences, King's College London, London, United Kingdom
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Delimont NM, Nickel S. Salivary cystatin SN is a factor predicting iron bioavailability after phytic acid rich meals in female participants. Int J Food Sci Nutr 2020; 72:559-568. [PMID: 33179561 DOI: 10.1080/09637486.2020.1846164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Phytic acid is an inhibitor of iron bioavailability, but it has been suggested that individuals may adapt to phytic acid over time, and that the salivary protein, cystatin SN, may be involved. This study evaluated the relationship between human cystatin SN levels and iron bioavailability after a phytic acid rich meal. Three groups of ten women consumed meals with: (1) 500 mg phytate sprinkles, (2) 500 mg phytate capsules, or (3) no phytic acid. Iron bioavailability was measured by the mealtime percentage of maximum iron recovery; cystatin SN was measured pre-and post-meal by enzyme-linked immunosorbent assay. Pre-to-post meal cystatin SN was positively correlated with improved iron bioavailability in group 1. Pre-to-post meal cystatin SN was correlated with improved iron absorption in groups 1 and 2. Cystatin SN recovery after phytic acid rich meals may be a physiological factor predicting iron bioavailability.
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Affiliation(s)
| | - Sarah Nickel
- Department of Medical Laboratory Sciences, Wichita State University, Wichita, KS, USA
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Vorland CJ, Mestre LM, Mendis SS, Brown AW. Within-group comparisons led to unsubstantiated conclusions in “Low-phytate wholegrain bread instead of high-phytate wholegrain bread in a total diet context did not improve iron status of healthy Swedish females: a 12-week, randomized, parallel-design intervention Study”. Eur J Nutr 2020; 59:2813-2814. [DOI: 10.1007/s00394-020-02287-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Reply to the comments by Vorland et al. on our paper: "low-phytate wholegrain bread instead of high-phytate wholegrain bread in a total diet context did not improve iron status of healthy Swedish females: a 12-week, randomized, parallel-design intervention study". Eur J Nutr 2020; 59:2815-2817. [PMID: 32648021 DOI: 10.1007/s00394-020-02288-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Delimont N, Nickel S. Food Pattern Modeling as an Alternative Assessment Method to Multiday Dietary Recalls for Iron-Related Nutrients: A Proof-of-Concept Study. Nutrients 2020; 12:E1911. [PMID: 32605218 PMCID: PMC7401284 DOI: 10.3390/nu12071911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/16/2020] [Accepted: 06/18/2020] [Indexed: 12/03/2022] Open
Abstract
There are barriers to in-depth memory-based dietary assessment techniques in community-based research. Food pattern modeling may be an alternative method to traditional assessment techniques. The objective of this study was to pilot a comparison of food pattern modeling to 24 h diet recalls for predicting hematological outcomes of iron status. Data from 3-24 h dietary recalls in 27 women were analyzed by two methods: mean dietary intake estimates or food pattern modeling. Food pattern modeling was used to determine the total inventory of foods consumed with iron, phytate, or ascorbic acid or iron-phytate ratios. Each variable was analyzed for its relationship to hemoglobin, ferritin, and acute iron absorption from a meal challenge study by creating receiver operating characteristic (ROC) curves. There were no differences in ROC curves or diagnostic accuracies between food pattern modeling or mean dietary intake estimates for iron, vitamin C, phytate, or phytate-iron ratios for estimating hemoglobin or ferritin values (p > 0.05). Food pattern modeling was inferior to mean dietary estimates for acute iron absorption, suggesting that more detailed methods may be necessary for studies with sensitive or acute dietary measurement outcomes. Food pattern modeling for total iron, vitamin C, phytate, and phytate-iron ratios may be comparable to detailed memory-based recalls for larger studies assessing the impact of foods on iron status.
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Affiliation(s)
- Nicole Delimont
- School of Nursing, Wichita State University, Wichita KS 67260, USA
| | - Sarah Nickel
- Department of Medical Laboratory Sciences, Wichita State University, Wichita, KS 67260, USA;
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