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Paoletti A, Courtney-Martin G, Elango R. Determining amino acid requirements in humans. Front Nutr 2024; 11:1400719. [PMID: 39091679 PMCID: PMC11291443 DOI: 10.3389/fnut.2024.1400719] [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: 03/14/2024] [Accepted: 07/05/2024] [Indexed: 08/04/2024] Open
Abstract
Amino acids form the building blocks of body protein. Dietary protein sources provide the amino acids needed, but protein sources vary widely in amio acid composition. To ensure humans can meet body demands for amino acids, amino acid intake recommendations are provided by the Dietary Reference Intakes (DRI) and by Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU). Current amino acid intake recommendations, however, are based on data collected predominantly from young adult males. The development of the minimally invasive indicator amino acid oxidation (IAAO) method has permitted the evaluation of amino acid requirements in various vulnerable populations. The purpose of this review is to discuss recent amino acid requirement studies in school-age children, pregnant females and the elderly determined using the IAAO technique. These requirements will help to inform evidence-based recommendations that will help to guide dietary guidelines.
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Affiliation(s)
- Alyssa Paoletti
- Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Glenda Courtney-Martin
- Research Institute, Hospital for Sick Children, Toronto, ON, Canada
- Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada
- Department of Kinesiology, University of Toronto, Toronto, ON, Canada
| | - Rajavel Elango
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
- School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada
- BC Children’s Hospital Research Institute, BC Children’s Hospital, Vancouver, BC, Canada
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2
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Millward DJ. Post-prandial tracer studies of protein and amino acid utilisation: what can they tell us about human amino acid and protein requirements? Br J Nutr 2024; 131:2005-2030. [PMID: 38606599 PMCID: PMC11361918 DOI: 10.1017/s0007114524000734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/26/2024] [Accepted: 03/13/2024] [Indexed: 04/13/2024]
Abstract
Nitrogen balance (NB), the principal methodology used to derive recommendations for human protein and amino acid requirements, has been widely criticised, and calls for increased protein and amino acid requirement recommendations have been made, often on the basis of post-prandial amino acid tracer kinetic studies of muscle protein synthesis, or of amino acid oxidation. This narrative review considers our knowledge of the homeostatic regulation of the FFM throughout the diurnal cycle of feeding and fasting and what can and has been learnt from post-prandial amino acid tracer studies, about amino acid and protein requirements. Within the FFM, muscle mass in well fed weight-stable adults with healthy lifestyles appears fixed at a phenotypic level within a wide range of habitual protein intakes. However homoeostatic regulation occurs in response to variation in habitual protein intake, with adaptive changes in amino acid oxidation which influence the magnitude of diurnal losses and gains of body protein. Post-prandial indicator amino acid oxidation (IAAO) studies have been introduced as an alternative to NB and to the logistically complex 24 h [13C-1] amino acid balance studies, for assessment of protein and amino acid requirements. However, a detailed examination of IAAO studies shows both a lack of concern for homeostatic regulation of amino acid oxidation and major flaws in their design and analytical interpretation, which seriously constrain their ability to provide reliable values. New ideas and a much more critical approach to existing work is needed if real progress is to be made in the area.
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Affiliation(s)
- D. Joe Millward
- Department of Nutritional Sciences, School of Biosciences & Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
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Pezzali JG, Lambie JG, Verbrugghe A, Shoveller AK. Minimum methionine requirement in adult cats as determined by indicator amino acid oxidation. J Anim Sci 2024; 102:skad411. [PMID: 38092464 PMCID: PMC10768993 DOI: 10.1093/jas/skad411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 12/12/2023] [Indexed: 01/07/2024] Open
Abstract
There is a lack of empirical data on the dietary Met requirement, in the presence of Cys or cystine, in adult cats. Thus, the aim of this study was to determine the Met requirement, in the presence of excess Cys, in adult cats at maintenance using the indicator amino acid oxidation (IAAO) technique. Six adult neutered male cats were initially selected and started the study. Cats were adapted to the basal diet sufficient in Met (0.24% dry matter, DM) for 14 d prior to being randomly allocated to one of eight dietary levels of Met (0.10%, 0.13%, 0.17%, 0.22%, 0.27%, 0.33%, 0.38%, and 0.43% DM). Different dietary Met concentrations were achieved by supplementing the basal diet with Met solutions. Alanine was additionally included in the solutions to produce isonitrogenous and isoenergetic diets. Cats underwent a 2-d adaptation period to each experimental diet prior to each IAAO study day. On IAAO study days, 13 meals were offered corresponding to 75% of each cat's daily food allowance. The remaining 25% of their daily food intake was offered after each IAAO study. A bolus dose of NaH13CO3 (0.44 mg kg-1) and l-[1-13C]-phenylalanine (13C-Phe; 4.8 mg kg-1) were provided in fifth and sixth meals, respectively, followed by a constant dose of 13C-Phe (1.04 mg kg-1) in the next meals. Breath samples were collected and total production of 13CO2 was measured every 25 min through respiration calorimetry chambers. Steady state of 13CO2 achieved over at least three breath collections was used to calculate oxidation of 13C-Phe (F13CO2). Competing models were applied using the NLMIXED procedure in SAS to determine the effects of dietary Met on 13CO2. Two cats were removed from the study as they did not eat all meals, which is required to achieve isotopic steady. A breakpoint for the mean Met requirement, with excess of Cys, was identified at 0.24% DM (22.63 mg kg-1) with an upper 95% confidence limit of 0.40% DM (37.71 mg·kg-1), on an energy density of 4,164 kcal of metabolizable energy/kg DM calculated using the modified Atwater factors. The estimated Met requirement, in the presence of excess of Cys, is higher than the current recommendations proposed by the National Research Council's Nutrient Requirement of Dogs and Cats, the Association of American Feed Control Officials, and the European Pet Food Industry Federation.
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Affiliation(s)
- Júlia Guazzelli Pezzali
- Center for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Guelph, ON, CanadaN1G 2W1
- Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506, USA
| | - Jocelyn G Lambie
- Center for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Guelph, ON, CanadaN1G 2W1
| | - Adronie Verbrugghe
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, CanadaN1G 2W1
| | - Anna K Shoveller
- Center for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Guelph, ON, CanadaN1G 2W1
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Manipulation of Amino Acid Levels with Artificial Diets Induces a Marked Anticancer Activity in Mice with Renal Cell Carcinoma. Int J Mol Sci 2022; 23:ijms232416132. [PMID: 36555771 PMCID: PMC9783696 DOI: 10.3390/ijms232416132] [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: 09/16/2022] [Revised: 11/29/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Targeted therapies with antiangiogenic drugs (e.g., sunitinib) and immune checkpoint inhibitors (e.g., anti-PD-1 antibodies) are the standard of care for patients with metastatic renal cell carcinoma. Although these treatments improve patient survival, they are rarely curative. We previously hypothesized that advanced cancers might be treated without drugs by using artificial diets in which the levels of specific amino acids (AAs) are manipulated. In this work, after showing that AA manipulation induces selective anticancer activity in renal cell carcinoma cells in vitro, we screened 18 artificial diets for anticancer activity in a challenging animal model of renal cell carcinoma. The model was established by injecting murine renal cell carcinoma (Renca) cells into the peritoneum of immunocompetent BALB/cAnNRj mice. Mice survival was markedly improved when their normal diet was replaced with our artificial diets. Mice fed a diet lacking six AAs (diet T2) lived longer than mice treated with sunitinib or anti-PD-1 immunotherapy; several animals lived very long or were cured. Controlling the levels of several AAs (e.g., cysteine, methionine, and leucine) and lipids was important for the anticancer activity of the diets. Additional studies are needed to further evaluate the therapeutic potential and mechanism of action of this simple and inexpensive anticancer strategy.
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Shoveller AK, Pezzali JG, House JD, Bertolo RF, Pencharz PB, Ball RO. Methionine and cysteine oxidation are regulated in a dose dependent manner by dietary Cys intake in neonatal piglets receiving enteral nutrition. PLoS One 2022; 17:e0275760. [PMID: 36301815 PMCID: PMC9612549 DOI: 10.1371/journal.pone.0275760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 09/22/2022] [Indexed: 11/18/2022] Open
Abstract
Methionine (Met) is an indispensable amino acid (AA) in piglets. Met can synthesize cysteine (Cys), and Cys has the ability to reduce the Met requirement by 40% in piglets. However, whether this sparing effect on Met is facilitated by downregulation of Cys synthesis has not been shown. This study investigated the effects of graded levels of Cys on Met and Cys oxidation, and on plasma AA concentrations. Piglets (n = 32) received a complete elemental diet via gastric catheters prior to being randomly assigned to one of the eight dietary Cys levels (0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.40, 0.50 g kg-1d-1) with an adequate Met concentration (0.25g kg-1d-1). Constant infusion of L-[1-14C]-Met and L-[1-14C]-Cys were performed for 6 h on d 6 and d 8 to determine Met and Cys oxidation, respectively. Met oxidation decreased as Cys intake increased (P<0.05). At higher Cys intakes (0.15 to 0.5g kg-1d-1), Met oxidation decreased (P<0.05) at a slower rate. Cys oxidation was similar (P>0.05) among dietary Cys intakes; however, a significant polynomial relationship was observed between Cys oxidation and intake (P<0.05, R2 = 0.12). Plasma Met concentrations increased (P<0.05) linearly with increasing levels of dietary Cys, while plasma Cys concentrations changed (P<0.05) in a cubic manner and the highest concentrations occurred at the highest intake levels. Increasing dietary levels of Cys resulted in a reduction in Met oxidation until the requirement for the total sulfur AA was met, indicating the sparing capacity by Cys of Met occurs through inhibition of the transsulfuration pathway in neonatal piglets.
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Affiliation(s)
- Anna K. Shoveller
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
| | - Julia G. Pezzali
- Department of Animal Biosciences, University of Guelph, Guelph, Ontario, Canada
| | - James D. House
- Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Robert F. Bertolo
- Department of Biochemistry, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada
| | - Paul B. Pencharz
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- The Research Institute, The Hospital for Sick Children, Toronto, Canada
- Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Ronald O. Ball
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- The Research Institute, The Hospital for Sick Children, Toronto, Canada
- Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
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Glycomacropeptide in PKU-Does It Live Up to Its Potential? Nutrients 2022; 14:nu14040807. [PMID: 35215457 PMCID: PMC8875363 DOI: 10.3390/nu14040807] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/30/2022] [Accepted: 02/07/2022] [Indexed: 02/01/2023] Open
Abstract
The use of casein glycomacropeptide (CGMP) as a protein substitute in phenylketonuria (PKU) has grown in popularity. CGMP is derived from κ casein and is a sialic-rich glycophosphopeptide, formed by the action of chymosin during the production of cheese. It comprises 20–25% of total protein in whey products and has key biomodulatory properties. In PKU, the amino acid sequence of CGMP has been adapted by adding the amino acids histidine, leucine, methionine, tyrosine and tryptophan naturally low in CGMP. The use of CGMP compared to mono amino acids (L-AAs) as a protein substitute in the treatment of PKU promises several potential clinical benefits, although any advantage is supported only by evidence from non-PKU conditions or PKU animal models. This review examines if there is sufficient evidence to support the bioactive properties of CGMP leading to physiological benefits when compared to L-AAs in PKU, with a focus on blood phenylalanine control and stability, body composition, growth, bone density, breath odour and palatability.
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May T, de la Haye B, Nord G, Klatt K, Stephenson K, Adams S, Bollinger L, Hanchard N, Arning E, Bottiglieri T, Maleta K, Manary M, Jahoor F. One-carbon metabolism in children with marasmus and kwashiorkor. EBioMedicine 2022; 75:103791. [PMID: 35030356 PMCID: PMC8761690 DOI: 10.1016/j.ebiom.2021.103791] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 11/24/2021] [Accepted: 12/16/2021] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Kwashiorkor is a childhood syndrome of edematous malnutrition. Its precise nutritional precipitants remain uncertain despite nine decades of study. Remarkably, kwashiorkor's disturbances resemble the effects of experimental diets that are deficient in one-carbon nutrients. This similarity suggests that kwashiorkor may represent a nutritionally mediated syndrome of acute one-carbon metabolism dysfunction. Here we report findings from a cross-sectional exploration of serum one-carbon metabolites in Malawian children. METHODS Blood was collected from children aged 12-60 months before nutritional rehabilitation: kwashiorkor (N = 94), marasmic-kwashiorkor (N = 43) marasmus (N = 118), moderate acute malnutrition (N = 56) and controls (N = 46). Serum concentrations of 16 one-carbon metabolites were quantified using LC/MS techniques, and then compared across participant groups. FINDINGS Twelve of 16 measured one-carbon metabolites differed significantly between participant groups. Measured outputs of one-carbon metabolism, asymmetric dimethylarginine (ADMA) and cysteine, were lower in marasmic-kwashiorkor (median µmol/L (± SD): 0·549 (± 0·217) P = 0·00045 & 90 (± 40) P < 0·0001, respectively) and kwashiorkor (0·557 (± 0·195) P < 0·0001 & 115 (± 50) P < 0·0001), relative to marasmus (0·698 (± 0·212) & 153 (± 42)). ADMA and cysteine were well correlated with methionine in both kwashiorkor and marasmic-kwashiorkor. INTERPRETATION Kwashiorkor and marasmic-kwashiorkor were distinguished by evidence of one-carbon metabolism dysfunction. Correlative observations suggest that methionine deficiency drives this dysfunction, which is implicated in the syndrome's pathogenesis. The hypothesis that kwashiorkor can be prevented by fortifying low quality diets with methionine, along with nutrients that support efficient methionine use, such as choline, requires further investigation. FUNDING The Hickey Family Foundation, the American College of Gastroenterology, the NICHD, and the USDA/ARS.
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Affiliation(s)
- Thaddaeus May
- Children's Nutrition Research Center, Baylor College of Medicine, One Baylor Plaza, Houston TX, USA.
| | | | | | - Kevin Klatt
- Children's Nutrition Research Center, Baylor College of Medicine, One Baylor Plaza, Houston TX, USA,Center for Precision Environmental Health, Baylor College of Medicine
| | | | | | - Lucy Bollinger
- Washington University in St. Louis School of Medicine, USA
| | - Neil Hanchard
- National Institutes of Health, USA,National Human Genome Research Institute, Nationl Institutes of Health
| | - Erland Arning
- Center of Metabolomics, Institute of Metabolic Disease, Baylor Scott and White Research Institute
| | - Teodoro Bottiglieri
- Center of Metabolomics, Institute of Metabolic Disease, Baylor Scott and White Research Institute
| | | | - Mark Manary
- Children's Nutrition Research Center, Baylor College of Medicine, One Baylor Plaza, Houston TX, USA,The University of Malawi College of Medicine, Malawi,Washington University in St. Louis School of Medicine, USA
| | - Farook Jahoor
- Children's Nutrition Research Center, Baylor College of Medicine, One Baylor Plaza, Houston TX, USA
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Neubauer C, Landecker H. A planetary health perspective on synthetic methionine. Lancet Planet Health 2021; 5:e560-e569. [PMID: 34390674 DOI: 10.1016/s2542-5196(21)00138-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 04/21/2021] [Accepted: 05/07/2021] [Indexed: 06/13/2023]
Abstract
Methionine is an amino acid that humans and farm animals must derive from food. This metabolite, a tightly regulated resource in ecosystems, has become a mass commodity in the global economy, with well over 1 million tons being produced annually from petroleum to fortify livestock feed. Viewed from the standpoint of planetary health, anthropogenic methionine synthesis is an important enabler of low-cost animal protein production, with interdependent but unexamined effects on human health and ecosystems. At a time when agrochemical engineering is shifting the way sulphur is assimilated and moves up our food chain, research suggests that dietary methionine restriction alone captures many healthspan benefits noted with calorie restriction. As such, methionine synthesis is an excellent exemplar of planetary scale anthropogenic activity that manifests at the molecular scale of cellular metabolism, with potential systemic effects on human health. In this Personal View we establish the scale and historical trajectory of the methionine industry and provide a preliminary model for tracing this amino acid through the food supply into the human body. We draw together insights across disparate publications of applied animal agriculture, human nutrition, and biomedical research to call for cross-disciplinary dialogue on responsible use of methionine-augmentation technologies.
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Affiliation(s)
- Cajetan Neubauer
- Institute of Arctic and Alpine Research, Colorado University, Boulder, CO, USA
| | - Hannah Landecker
- Department of Sociology and Institute for Society and Genetics, University of California, Los Angeles, CA, USA.
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Kožich V, Stabler S. Lessons Learned from Inherited Metabolic Disorders of Sulfur-Containing Amino Acids Metabolism. J Nutr 2020; 150:2506S-2517S. [PMID: 33000152 DOI: 10.1093/jn/nxaa134] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/12/2020] [Accepted: 04/17/2020] [Indexed: 12/16/2022] Open
Abstract
The metabolism of sulfur-containing amino acids (SAAs) requires an orchestrated interplay among several dozen enzymes and transporters, and an adequate dietary intake of methionine (Met), cysteine (Cys), and B vitamins. Known human genetic disorders are due to defects in Met demethylation, homocysteine (Hcy) remethylation, or cobalamin and folate metabolism, in Hcy transsulfuration, and Cys and hydrogen sulfide (H2S) catabolism. These disorders may manifest between the newborn period and late adulthood by a combination of neuropsychiatric abnormalities, thromboembolism, megaloblastic anemia, hepatopathy, myopathy, and bone and connective tissue abnormalities. Biochemical features include metabolite deficiencies (e.g. Met, S-adenosylmethionine (AdoMet), intermediates in 1-carbon metabolism, Cys, or glutathione) and/or their accumulation (e.g. S-adenosylhomocysteine, Hcy, H2S, or sulfite). Treatment should be started as early as possible and may include a low-protein/low-Met diet with Cys-enriched amino acid supplements, pharmacological doses of B vitamins, betaine to stimulate Hcy remethylation, the provision of N-acetylcysteine or AdoMet, or experimental approaches such as liver transplantation or enzyme replacement therapy. In several disorders, patients are exposed to long-term markedly elevated Met concentrations. Although these conditions may inform on Met toxicity, interpretation is difficult due to the presence of additional metabolic changes. Two disorders seem to exhibit Met-associated toxicity in the brain. An increased risk of demyelination in patients with Met adenosyltransferase I/III (MATI/III) deficiency due to biallelic mutations in the MATIA gene has been attributed to very high blood Met concentrations (typically >800 μmol/L) and possibly also to decreased liver AdoMet synthesis. An excessively high Met concentration in some patients with cystathionine β-synthase deficiency has been associated with encephalopathy and brain edema, and direct toxicity of Met has been postulated. In summary, studies in patients with various disorders of SAA metabolism showed complex metabolic changes with distant cellular consequences, most of which are not attributable to direct Met toxicity.
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Affiliation(s)
- Viktor Kožich
- Department of Pediatrics and Adolescent Medicine, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic
| | - Sally Stabler
- Department of Medicine, University of Colorado School of Medicine Anschutz Medical Campus, Aurora, CO, USA
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Mao D, Chen F, Wang R, Bai P, Zhang Y, Zhao W, Chen J, Yang L, Yang X, Li M. Protein Requirements of Elderly Chinese Adults Are Higher than Current Recommendations. J Nutr 2020; 150:1208-1213. [PMID: 32140711 DOI: 10.1093/jn/nxaa031] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 11/27/2019] [Accepted: 01/30/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Due to a lack of research data on the protein requirements of the elderly in China, the estimated average requirement (EAR) and the recommended nutrient intake (RNI) of protein in the elderly remain the same as those in young and middle-aged people at 0.98 g/(kg·d). OBJECTIVE The objective of this study was to determine the protein requirements of healthy Chinese adults >65y old through use of the indicator amino acid oxidation (IAAO) method. METHODS Seven healthy adult men and 7 healthy adult women participated in the study, with protein intakes ranging from 0.3 to 1.8 g/(kg·d). The diets were isocaloric and provided energy at a 1.5 resting energy expenditure. Protein was given based on the lactalbumin. Phenylalanine and tyrosine were added to protein doses of 0.3-1.5 g/kg according to the highest dose of protein content [1.8 g/(kg·d)]. Phenylalanine and tyrosine concentrations were kept constant at each protein dose. The mean protein requirement was determined by applying a nonlinear mixed-effects model analysis to the F13CO2, which identified a breakpoint in F13CO2 in response to graded amounts of protein. This trial was registered with the Chinese clinical trial registry as ChiCTR-BOC-17010930. RESULTS Protein EAR and RNI for healthy elderly Chinese adults were determined to be 0.91 and 1.17 g/(kg·d), respectively, based on the indicator amino acid oxidation technique. CONCLUSIONS The estimates of protein requirements for Chinese adults >65 y in the present study are 3.4% and 19.4% higher than the current estimated requirements, 0.88 g/(kg·d) for EAR and 0.98 g/(kg·d) for RNI.
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Affiliation(s)
- Deqian Mao
- Key Laboratory of Trace Element Nutrition, National Health Commission; National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Fengge Chen
- Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang, Hebei, China
| | - Rui Wang
- Key Laboratory of Trace Element Nutrition, National Health Commission; National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ping Bai
- Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang, Hebei, China
| | - Yanhong Zhang
- Zhengding County Center for Disease Control and Prevention, Zhengding, Hebei, China
| | - Wei Zhao
- Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang, Hebei, China
| | - Jing Chen
- Key Laboratory of Trace Element Nutrition, National Health Commission; National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Lichen Yang
- Key Laboratory of Trace Element Nutrition, National Health Commission; National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xiaoguang Yang
- Key Laboratory of Trace Element Nutrition, National Health Commission; National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Min Li
- Key Laboratory of Trace Element Nutrition, National Health Commission; National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing, China
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11
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Elango R, Humayun MA, Turner JM, Rafii M, Langos V, Ball RO, Pencharz PB. Total Sulfur Amino Acid Requirements Are Not Altered in Children with Chronic Renal Insufficiency, but Minimum Methionine Needs Are Increased. J Nutr 2017; 147:1954-1959. [PMID: 28855417 DOI: 10.3945/jn.116.244301] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/18/2017] [Accepted: 07/31/2017] [Indexed: 11/14/2022] Open
Abstract
Background: The total sulfur amino acid (TSAA) and minimum Met requirements have been previously determined in healthy children. TSAA metabolism is altered in kidney disease. Whether TSAA requirements are altered in children with chronic renal insufficiency (CRI) is unknown.Objective: We sought to determine the TSAA (Met in the absence of Cys) requirements and minimum Met (in the presence of excess Cys) requirements in children with CRI.Methods: Five children (4 boys, 1 girl) aged 10 ± 2.6 y with CRI were randomly assigned to receive graded intakes of Met (0, 5, 10, 15, 25, and 35 mg · kg-1 · d-1) with no Cys in the diet. Four of the children (3 boys, 1 girl) were then randomly assigned to receive graded dietary intakes of Met (0, 2.5, 5, 7.5, 10, and 15 mg · kg-1 · d-1) with 21 mg · kg-1 · d-1 Cys. The mean TSAA and minimum Met requirements were determined by measuring the oxidation of l-[1-13C]Phe to 13CO2 (F13CO2). A 2-phase linear-regression crossover analysis of the F13CO2 data identified a breakpoint at minimal F13CO2 Urine samples collected from all study days and from previous studies of healthy children were measured for sulfur metabolites.Results: The mean and population-safe (upper 95% CI) intakes of TSAA and minimum Met in children with CRI were determined to be 12.6 and 15.9 mg · kg-1 · d-1 and 7.3 and 10.9 mg · kg-1 · d-1, respectively. In healthy school-aged children the mean and upper 95% CI intakes of TSAA and minimum Met were determined to be 12.9 and 17.2 mg · kg-1 · d-1 and 5.8 and 7.3 mg · kg-1 · d-1, respectively. A comparison of the minimum Met requirements between healthy children and children with CRI indicated significant (P < 0.05) differences.Conclusion: These results suggest that children with CRI have a similar mean and population-safe TSAA to that of healthy children, suggesting adequate Cys synthesis via transsulfuration, but higher minimum Met requirement, suggesting reduced remethylation rates.
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Affiliation(s)
- Rajavel Elango
- BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; .,Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mohammad A Humayun
- Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Justine M Turner
- Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Mahroukh Rafii
- Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Veronika Langos
- Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ronald O Ball
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada; and Departments of
| | - Paul B Pencharz
- Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.,Paediatrics and.,Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
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12
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Robinson JL, Harding SV, Brunton JA, Bertolo RF. Dietary Methyl Donors Contribute to Whole-Body Protein Turnover and Protein Synthesis in Skeletal Muscle and the Jejunum in Neonatal Piglets. J Nutr 2016; 146:2007-2012. [PMID: 27581577 DOI: 10.3945/jn.115.226035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 07/27/2016] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The neonatal methionine requirement must consider not only the high demand for rapid tissue protein expansion but also the demands as the precursor for a suite of critical transmethylation reactions. However, methionine metabolism is inherently complex because upon transferring its methyl group during transmethylation, methionine can be reformed by the dietary methyl donors choline (via betaine) and folate. OBJECTIVE We sought to determine whether dietary methyl donors contribute to methionine availability for protein synthesis in neonatal piglets. METHODS Yucatan miniature piglets aged 4-8 d were fed a diet that provided 38 μg folate/(kg·d), 60 mg choline/(kg·d), and 238 mg betaine/(kg·d) [methyl-sufficient (MS); n = 8] or a diet devoid of these methyl precursors [methyl-deficient (MD); n = 8]. After 5 d, dietary methionine was reduced from 0.30 to 0.20 g/(kg·d) in both groups. On day 6, piglets received a constant [1-13C]phenylalanine infusion to measure whole-body protein kinetics, and on day 8 they received a constant [3H-methyl]methionine infusion to measure tissue-specific protein synthesis in skeletal muscle, the liver, and the jejunum. RESULTS Whole-body phenylalanine flux, protein synthesis, and protein breakdown were 13%, 12%, and 22% lower, respectively, in the MD group than in the MS group (P < 0.05). Reduced whole-body protein synthesis in the MD piglets was attributed to 50% lower protein synthesis in skeletal muscle and the jejunum than in the MS piglets (P < 0.05). Furthermore, methionine availability in skeletal muscle was halved in piglets fed the MD diet (P < 0.05), and the specific radioactivity of methionine was doubled in the jejunum of MD piglets (P < 0.05), suggesting lower intestinal remethylation. Liver protein synthesis did not significantly differ between the groups, but secreted proteins were not measured. CONCLUSIONS Dietary methyl donors can affect whole-body and tissue-specific protein synthesis in neonatal piglets and should be considered when determining the methionine requirement.
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Affiliation(s)
- Jason L Robinson
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada; and
| | - Scott V Harding
- Faculty of Life Sciences and Medicine, Diabetes and Nutritional Sciences Division, King's College London, London, United Kingdom
| | - Janet A Brunton
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada; and
| | - Robert F Bertolo
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada; and
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Robinson JL, Bertolo RF. The Pediatric Methionine Requirement Should Incorporate Remethylation Potential and Transmethylation Demands. Adv Nutr 2016; 7:523-34. [PMID: 27184279 PMCID: PMC4863267 DOI: 10.3945/an.115.010843] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The metabolic demand for methionine is great in neonates. Indeed, methionine is the only indispensable sulfur amino acid and is required not only for protein synthesis and growth but is also partitioned to a greater extent to transsulfuration for cysteine and taurine synthesis and to >50 transmethylation reactions that serve to methylate DNA and synthesize metabolites, including creatine and phosphatidylcholine. Therefore, the pediatric methionine requirement must accommodate the demands of rapid protein turnover as well as vast nonprotein demands. Because cysteine spares the methionine requirement, it is likely that the dietary provision of transmethylation products can also feasibly spare methionine. However, understanding the requirement of methionine is further complicated because demethylated methionine can be remethylated by the dietary methyl donors folate and betaine (derived from choline). Intakes of dietary methyl donors are highly variable, which is of particular concern for newborns. It has been demonstrated that many populations have enhanced requirements for these nutrients, and nutrient fortification may exacerbate this phenomenon by selecting phenotypes that increase methyl requirements. Moreover, higher transmethylation rates can limit methyl supply and affect other transmethylation reactions as well as protein synthesis. Therefore, careful investigations are needed to determine how remethylation and transmethylation contribute to the methionine requirement. The purpose of this review is to support our hypothesis that dietary methyl donors and consumers can drive methionine availability for protein synthesis and transmethylation reactions. We argue that nutritional strategies in neonates need to ensure that methionine is available to meet requirements for growth as well as for transmethylation products.
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Affiliation(s)
| | - Robert F Bertolo
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
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Abstract
During the past 25 years a significant amount of research has been conducted to determine amino acid requirements in humans. This is primarily due to advancements in the application of stable isotopes to examine amino acid requirements. The indicator amino acid oxidation (IAAO) method has emerged as a robust and minimally invasive technique to identify requirements. The IAAO method is based on the concept that when one indispensable dietary amino acid (IDAA) is deficient for protein synthesis, then the excess of all other IDAA, including the indicator amino acid, will be oxidized. With increasing intakes of the limiting amino acid, IAAO will decrease, reflecting increasing incorporation into protein. Once the requirement for the limiting amino acid is met there will be no further change in the indicator oxidation. The IAAO method has been systematically applied to determine most IDAA requirements in adults. The estimates are comparable to the values obtained using the more elaborate 24h-indicator amino acid oxidation and balance (24h-IAAO/IAAB) model. Due to its non-invasive nature the IAAO method has also been used to determine requirements for amino acids in neonates, children and in disease. The IAAO model has recently been applied to determine total protein requirements in humans. The IAAO method is rapid, reliable and has been used to determine amino acid requirements in different species, across the life cycle and in disease. The recent application of IAAO to determine protein requirements in humans is novel and has significant implications for dietary protein intake recommendations globally.
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Huang L, Hogewind-Schoonenboom JE, van Dongen MJA, de Groof F, Voortman GJ, Schierbeek H, Twisk JWR, Vermes A, Chen C, Huang Y, van Goudoever JB. Methionine requirement of the enterally fed term infant in the first month of life in the presence of cysteine. Am J Clin Nutr 2012; 95:1048-54. [PMID: 22492372 DOI: 10.3945/ajcn.111.028779] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The essential amino acid methionine can be used for protein synthesis but also serves as a precursor for homocysteine and cysteine. OBJECTIVE The objective of this study was to determine the minimal obligatory methionine requirement of infants in the presence of excess cysteine (91 mg ⋅ kg(-1) ⋅ d(-1)) by using the indicator amino acid oxidation (IAAO) method with l-[1-(13)C]phenylalanine as the indicator. DESIGN Fully enterally fed term infants <1 mo of age were randomly assigned to methionine intakes that ranged from 3 to 59 mg ⋅ kg(-1) ⋅ d(-1) as part of an elemental formula. After 1 d of adaptation to the test diet, [(13)C]bicarbonate and l-[1-(13)C]phenylalanine tracers were given enterally. Breath samples were collected at baseline and during isotopic plateaus. The mean methionine requirement was determined by using biphasic linear regression crossover analysis on the fraction of (13)CO(2) recovery from l-[1-(13)C]phenylalanine oxidation (F(13)CO(2)). Data are presented as means ± SDs. RESULTS Thirty-three neonates (gestational age: 39 ± 1 wk) were studied at 13 ± 6 d. With increasing methionine intakes, F(13)CO(2) decreased until a methionine intake of 38 mg ⋅ kg(-1) ⋅ d(-1); additional increases in methionine intake did not affect F(13)CO(2). The mean methionine requirement was determined at 38 mg ⋅ kg(-1) ⋅ d(-1), and the upper and lower CIs were 48 and 27 mg ⋅ kg(-1) ⋅ d(-11), respectively (P < 0.0001, r(2) = 0.59). CONCLUSIONS Although the current recommended methionine intake of 28 mg ⋅ kg(-1) ⋅ d(-1) is within the CIs of our study, the estimated mean requirement is substantially higher. However, most of the infant formulas provide a methionine intake of 49-80 mg ⋅ kg(-1) ⋅ d(-1), which is above the upper CI of our study. This trial was registered at www.trialregister.nl as NTR1610.
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Affiliation(s)
- Lisha Huang
- Department of Pediatrics, Division of Neonatology, Medical Centre-Sophia Children's Hospital, Rotterdam, Netherlands
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Sahni N, Gupta KL, Rana SV, Prasad R, Bhalla AK. Intake of antioxidants and their status in chronic kidney disease patients. J Ren Nutr 2012; 22:389-99. [PMID: 22227184 DOI: 10.1053/j.jrn.2011.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 09/03/2011] [Accepted: 09/03/2011] [Indexed: 11/11/2022] Open
Abstract
OBJECTIVE To evaluate the intake and status of antioxidants in chronic kidney disease (CKD) patients. DESIGN Randomized control trial. SETTING Hospital outpatient department. SUBJECTS One hundred eighty-five subjects (145 predialysis CKD patients and 40 apparently healthy controls) were enrolled for this study. The patients were divided into moderate and severe renal failure groups based on their creatinine and glomerular filtration rates. INTERVENTION All patients completed a food frequency questionnaire, 24-hour dietary recall form, and anthropometric measurements and underwent biochemical and antioxidant lab tests. MAIN OUTCOME MEASURES Dietary intake, anthropometry, biochemical measures of blood and antioxidant enzymes as well as oxidative stress. RESULTS Overall, the diet was significantly lower in antioxidant-rich food intake in all the CKD patients as compared with controls. The oxidative stress measured in blood was found to be in consonance with the intake from diet. CONCLUSION Micronutrients play a major role in the antioxidant status of the patients and must be monitored, as deficiency of these might elevate the oxidative stress of the body, especially in the chronic diseases.
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Affiliation(s)
- N Sahni
- Department of Dietetics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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Elango R, Humayun MA, Ball RO, Pencharz PB. Protein requirement of healthy school-age children determined by the indicator amino acid oxidation method. Am J Clin Nutr 2011; 94:1545-52. [PMID: 22049165 DOI: 10.3945/ajcn.111.012815] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The current Dietary Reference Intake (DRI) recommendations for protein requirements in children are based on a factorial estimate and have not been directly determined. OBJECTIVE The objective of the current study was to determine the protein requirement in healthy, school-age children by measuring the oxidation of L-[1-(13)C]-phenylalanine to (13)CO(2) [label tracer oxidation (F(13)CO(2))] in response to graded intakes of protein. DESIGN Seven healthy children (6-11 y old) each randomly received a minimum of 7 protein intakes (range: 0.1-2.56 g · kg(-1) · d(-1)) for a total of 56 studies. The diets provided energy at 1.7 times the resting energy expenditure and were made isocaloric by using carbohydrate. Protein was given as an amino acid mixture on the basis of the egg-protein pattern, except for phenylalanine and tyrosine intakes, which were maintained constant across intakes. The mean protein requirement was determined by applying a 2-phase linear regression crossover analysis on F(13)CO(2) data, which identified a breakpoint (requirement) at minimal F(13)CO(2) in response to graded amounts of protein intake. RESULTS Mean and population-safe (upper 95% CI) protein requirements were determined to be 1.3 and 1.55 g · kg(-1) · d(-1), respectively. These results are significantly higher than the mean and population-safe protein requirements currently recommended by the DRI 2005 for macronutrients (0.76 and 0.95 g · kg(-1) · d(-1), respectively). CONCLUSION To our knowledge, this study was the first to directly estimate protein requirements in children by using stable isotopes and indicated that current recommendations are severely underestimated.
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Affiliation(s)
- Rajavel Elango
- Research Institute, The Hospital for Sick Children, Toronto, Canada
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Tomlinson C, Rafii M, Ball RO, Pencharz P. The significance of d-isomers in stable isotope studies in humans is dependent on the age of the subject and the amino acid tracer. Metabolism 2010; 59:14-9. [PMID: 19709694 DOI: 10.1016/j.metabol.2009.06.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 06/02/2009] [Accepted: 06/29/2009] [Indexed: 11/18/2022]
Abstract
d-Amino acids (d-AAs) in stable isotope tracers may result in erroneous estimates of enrichment, particularly if urine is used as a surrogate for plasma enrichment. Previous studies suggest that a d-AA content of less than 0.2% will not result in significant error in studies with adult humans. To describe the effects of d-AA content of less than 0.2%, in 3 different AA tracers, on isotope enrichment in urine and plasma, arginine, proline, and phenylalanine (Phe) tracers were given enterally to human neonates. Enrichment was measured in urine and plasma using chiral chromatography and tandem mass spectrometry. The Phe tracer was also given parenterally to human neonates and enterally to children and adults to further characterize the d-AA effect. All isotopes had a confirmed d-AA content of less than 0.2%. Labeled d-arginine resulted in an overestimate for enrichment of 20% in plasma and 87% in urine. A smaller effect was seen for d-Phe, which resulted in a 5% overestimate for plasma and 40% in urine. d-Proline had no significant effect. Using the same Phe tracer, a developmental effect was found, with a reduction in the overestimate in children compared with infants and no effect on enrichment in adults. Investigators using commercially produced, stable isotope-labeled AAs need to be aware that there is no safe level of d contamination; a d-AA content less than 0.2% may result in significant overestimate for enrichment, even in plasma, for infants and children. This source of error can be avoided by the use of chiral chromatography.
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Affiliation(s)
- Chris Tomlinson
- Department of Paediatrics, The Hospital for Sick Children, Toronto, M5G1X8 Canada
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Elango R, Humayun MA, Ball RO, Pencharz PB. Evidence that protein requirements have been significantly underestimated. Curr Opin Clin Nutr Metab Care 2010; 13:52-7. [PMID: 19841581 DOI: 10.1097/mco.0b013e328332f9b7] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review discusses recent evidence that suggests a significant underestimation of protein requirements in adult humans. RECENT FINDINGS Traditionally, total protein requirements for humans have been determined using nitrogen balance. The recent Dietary Reference Intake recommendations for mean and population-safe intakes of 0.66 and 0.8 g/kg/day, respectively, of high-quality protein in adult humans are based on a meta-analysis of nitrogen balance studies using single linear regression analysis. We reanalyzed existing nitrogen balance studies using two-phase linear regression analysis and obtained mean and safe protein requirements of 0.91 and 0.99 g/kg/day, respectively. The two-phase linear regression analysis is considered more appropriate for biological analysis of dose-response curves. Considering the inherent problems associated with the nitrogen balance method, we developed an alternative method, the indicator amino acid oxidation technique, to determine protein requirements The mean and population-safe requirements in adult men were determined to be 0.93 and 1.2 g/kg/day and are 41 and 50%, respectively, higher than the current Dietary Reference Intakes recommendations. SUMMARY The indicator amino acid oxidation-based requirement values of 0.93 and 1.2 g protein/kg/day and the reanalysis of existing nitrogen balance studies are significantly higher than current recommendations. Therefore, there is an urgent need to reassess recommendations for protein intake in adult humans.
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Affiliation(s)
- Rajavel Elango
- The Research Institute, The Hospital for Sick Children, Toronto, Canada
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Pillai RR, Elango R, Muthayya S, Ball RO, Kurpad AV, Pencharz PB. Lysine requirement of healthy, school-aged Indian children determined by the indicator amino acid oxidation technique. J Nutr 2010; 140:54-9. [PMID: 19923398 DOI: 10.3945/jn.109.113357] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We recently reported the lysine requirement of school-aged children living in Canada consuming a mixed diet to be 35 mg.kg(-1).d(-1). Because the majority of children in the world live on cereal-based diets in developing countries, we measured the daily lysine requirement in healthy children living in India and consuming a mostly cereal-based diet. Our objective in this study was to determine the lysine requirement in healthy, school-aged children in the developing world by using the indicator amino acid oxidation method with l-[1-(13)C] phenylalanine. Six healthy, school-aged children consumed 7 levels of lysine (5, 15, 25, 35, 50, 65, and 80 mg.kg(-1).d(-1)) each in a random order along with an amino acid mixture providing energy and protein intakes of 1.7 x resting energy expenditure and 1.5 g.kg(-1).d(-1), respectively. The mean lysine requirement was determined by applying a 2-phase linear regression crossover analysis on tracer oxidation (F(13)CO(2)) data, which identified a breakpoint (requirement) at minimal F(13)CO(2) in response to the graded lysine intakes. The mean lysine requirements with the upper 95% CI for children were determined to be 33.5 and 46.6 mg.kg(-1).d(-1), respectively, by breakpoint analysis of the F(13)CO(2) data. The mean lysine requirements of Indian children were almost identical to that of Canadian children (35 mg.kg(-1).d(-1)). There is no evidence for any adaptation in lysine requirements in children from developing countries such as India.
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Affiliation(s)
- Raja R Pillai
- Division of Nutrition, St. John's Research Institute, St. John's National Academy of Health Sciences, Bangalore 560034, India
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Elango R, Humayun MA, Ball RO, Pencharz PB. Indicator amino acid oxidation is not affected by period of adaptation to a wide range of lysine intake in healthy young men. J Nutr 2009; 139:1082-7. [PMID: 19369367 DOI: 10.3945/jn.108.101147] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The number of days of adaptation to a specific amino acid intake required prior to the determination of amino acid requirements using the indicator amino acid oxidation method (IAAO) is still in debate. In this study, our objective was to determine whether adaptation for 8 h, 3 d, and 7 d to a wide range of lysine intakes had any effect on the oxidation of the indicator amino acid, l-[1-(13)C]phenylalanine, to (13)CO(2) (F(13)CO(2)). Five healthy young men randomly received each of 4 levels of lysine (5, 20, 35, and 70 mg x kg(-1) x d(-1)) along with an amino acid mixture to achieve a protein intake of 1.0 g x kg(-1) x d(-1) and energy intake of 1.5x resting energy expenditure during 4 separate 7-d study periods. IAAO studies were conducted on d 1, 3, and 7. During each study day, oral consumption of l-[1-(13)C]phenylalanine was followed by collection of breath for F(13)CO(2) and plasma for measurement of phenylalanine enrichment. F(13)CO(2) was affected by lysine intake but did not differ among adaptation periods of 8 h, 3 d, or 7 d. Phenylalanine flux was not significantly affected by period of adaptation. These results suggest that the minimally invasive IAAO model, where participants are adapted prior to protein intake for 2 d followed by study day adaptation to the test amino acid intake for 8 h, may be sufficient to estimate individual amino acid requirements in healthy young men.
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Affiliation(s)
- Rajavel Elango
- The Research Institute, The Hospital for Sick Children, Toronto M5G 1X8, Canada
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Taylor M, Chapman R, Beyaert R, Hernández-Sebastià C, Marsolais F. Seed storage protein deficiency improves sulfur amino acid content in common bean (Phaseolus vulgaris L.): redirection of sulfur from gamma-glutamyl-S-methyl-cysteine. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:5647-54. [PMID: 18588315 DOI: 10.1021/jf800787y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The contents of sulfur amino acids in seeds of common bean ( Phaseolus vulgaris L.) are suboptimal for nutrition. They accumulate large amounts of a gamma-glutamyl dipeptide of S-methyl-cysteine, a nonprotein amino acid that cannot substitute for methionine or cysteine in the diet. Protein accumulation and amino acid composition were characterized in three genetically related lines integrating a progressive deficiency in major seed storage proteins, phaseolin, phytohemagglutinin, and arcelin. Nitrogen, carbon, and sulfur contents were comparable among the three lines. The contents of S-methyl-cysteine and gamma-glutamyl-S-methyl-cysteine were progressively reduced in the mutants. Sulfur was shifted predominantly to the protein cysteine pool, while total methionine was only slightly elevated. Methionine and cystine contents (mg per g protein) were increased by up to ca. 40%, to levels slightly above FAO guidelines on amino acid requirements for human nutrition. These findings may be useful to improve the nutritional quality of common bean.
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Affiliation(s)
- Meghan Taylor
- Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, 1391 Sandford Street, London, Ontario, N5V 4T3, Canada
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Riedijk MA, Voortman G, van Beek RHT, Baartmans MGA, Wafelman LS, van Goudoever JB. Cyst(e)ine requirements in enterally fed very low birth weight preterm infants. Pediatrics 2008; 121:e561-7. [PMID: 18283068 DOI: 10.1542/peds.2007-0494] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Optimal nutrition is of utmost importance for the preterm infant's later health and developmental outcome. Amino acid requirements for preterm infants differ from those for term and older infants, because growth rates differ. Some nonessential amino acids, however, cannot be sufficiently synthesized endogenously. Cyst(e)ine is supposed to be such a conditionally essential amino acid in preterm infants. The objective of this study was to determine, at 32 and 35 weeks' postmenstrual age, cyst(e)ine requirements in fully enterally fed very low birth weight preterm infants with gestational ages of <29 weeks. METHODS Infants were randomly assigned to 1 of the 5 graded cystine test diets that contained generous amounts of methionine. Cyst(e)ine requirement was determined with the indicator amino acid oxidation technique ([1-(13)C]phenylalanine) after 24-hour adaptation. RESULTS Fractional [1-(13)C]phenylalanine oxidation was established in 47 very low birth weight preterm infants (mean gestational age: 28 weeks +/- 1 week SD; birth weight: 1.07 kg +/- 0.21 kg SD). Increase in dietary cyst(e)ine intake did not result in a decrease in fractional [1-(13)C]phenylalanine oxidation. CONCLUSIONS These data do not support the hypothesis that endogenous cyst(e)ine synthesis is limited in very low birth weight preterm infants with gestational ages of <29 weeks, both at 32 and 35 weeks postmenstrual age. It is safe to conclude that cyst(e)ine requirement is <18 mg/kg per day in enterally fed very low birth weight preterm infants who are older than 32 weeks' postmenstrual age and whose methionine intake is adequate. Therefore, cyst(e)ine is probably not a conditionally essential amino acid in these infants.
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Affiliation(s)
- Maaike A Riedijk
- Erasmus MC-Sophia Children's Hospital, Department of Pediatrics, Division of Neonatology, Dr Molewaterplein 60, 3015 GJ, Rotterdam, The Netherlands
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Elango R, Ball RO, Pencharz PB. Indicator amino acid oxidation: concept and application. J Nutr 2008; 138:243-6. [PMID: 18203885 DOI: 10.1093/jn/138.2.243] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The indicator amino acid oxidation (IAAO) method is based on the concept that when 1 indispensable amino acid (IDAA) is deficient for protein synthesis, then all other IDAA, including the indicator amino acid, will be oxidized. With increasing intakes of the limiting amino acid, IAAO will decrease, reflecting increasing incorporation into protein. Once the requirement for the limiting amino acid is met, there will be no further change in the indicator oxidation. Originally, the IAAO method was designed to determine amino acid requirements in growing pigs. The minimally invasive IAAO method developed in humans has been systematically applied to determine IDAA requirements in adults. Due to its noninvasive nature, the IAAO method has also been used to determine requirements for amino acids in neonates and children, and in disease. The IAAO model has recently been applied to determine the metabolic availability (MA) of amino acids from dietary proteins and to determine total protein requirements. The IAAO method is robust, rapid, and reliable; it has been used to determine amino acid requirements in different species, across the life cycle, and in diseased populations. The recent application of IAAO to determine MA of amino acids and protein requirements is also very novel.
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Affiliation(s)
- Rajavel Elango
- Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
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Use of N-acetyl cysteine for the treatment of parenteral nutrition-induced liver disease in children receiving home parenteral nutrition. J Pediatr Gastroenterol Nutr 2008; 46:220-3. [PMID: 18223385 DOI: 10.1097/mpg.0b013e3180653ce6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
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Abstract
PURPOSE OF REVIEW To discuss recent amino acid requirement studies in adult humans and school-age children, primarily determined using the indicator amino acid oxidation technique. RECENT FINDINGS Using the minimally invasive indicator amino acid oxidation model, requirements for most indispensable amino acids have been defined in adult humans. The estimates are comparable to the values obtained using the more elaborate 24-h indicator amino acid oxidation and balance model. The less-invasive indicator amino acid oxidation model has also been successfully applied to define requirements in healthy school-age children and children with disease. A recent adaptation of the indicator amino acid oxidation method to determine protein requirements in adult humans resulted in mean and safe values of 0.93 and 1.2 g protein/kg/day, respectively. These estimates are 40-50% higher than current recommendations and suggest an urgent need to reassess recommendations for protein intake in humans. SUMMARY In summary, indicator amino acid oxidation is a robust technique, and has resulted in the definition of amino acid and protein requirements in adult humans and children. A wider application of the technique in other vulnerable populations across life stages and in other diseases is now possible.
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Affiliation(s)
- Rajavel Elango
- The Research Institute, The Hospital for Sick Children, Toronto, Canada
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Elango R, Humayun MA, Ball RO, Pencharz PB. Lysine requirement of healthy school-age children determined by the indicator amino acid oxidation method. Am J Clin Nutr 2007; 86:360-5. [PMID: 17684206 DOI: 10.1093/ajcn/86.2.360] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The current Dietary Reference Intake (DRI) recommendations for lysine requirements in children are based on a factorial estimate. OBJECTIVE The objective of the current study was to determine the lysine requirement in healthy school-age children by measuring the oxidation of l-[1-(13)C]phenylalanine to (13)CO(2) (F(13)CO(2)) in response to graded intakes of lysine. DESIGN Five healthy school-age children randomly received each of 7 lysine intakes (5, 15, 25, 35 50, 65, and 80 mg x kg(-1) x d(-1)) along with an amino acid mixture to give a final calculated protein intake of 1.5 g x kg(-1) x d(-1) and an energy intake of 1.7 x resting energy expenditure (REE). The mean lysine requirement was determined by applying 2-phase linear regression crossover analysis on F(13)CO(2) data, which identified a breakpoint (requirement) at minimal F(13)CO(2) in response to graded lysine intakes. RESULTS The mean and population-safe (upper 95% CI) lysine requirements were determined to be 35 and 58 mg x kg(-1) x d(-1), respectively. CONCLUSIONS The mean and population-safe lysine requirements for children are similar to those for adults (36 and 52 mg x kg(-1) x d(-1), respectively), which suggests that the findings from the current study reflect predominantly the maintenance lysine requirements in children and not all requirements for growth. Therefore, to ensure age-appropriate growth in school-age children, we propose the addition of the requirement of lysine for growth (approximately 6 mg x kg(-1) x d(-1)) to the mean estimate. The new mean and population-safe lysine requirements are 41 and 58 mg x kg(-1) x d(-1), respectively; these values are significantly higher than the current DRIs of 37 and 46 mg x kg(-1) x d(-1), respectively.
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Affiliation(s)
- Rajavel Elango
- Research Institute, The Hospital for Sick Children, Toronto, Canada
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Anderson CL, Iyer SS, Ziegler TR, Jones DP. Control of extracellular cysteine/cystine redox state by HT-29 cells is independent of cellular glutathione. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1069-75. [PMID: 17567723 DOI: 10.1152/ajpregu.00195.2007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human cell lines regulate the redox state (E(h)) of the cysteine/cystine (Cys/CySS) couple in culture medium to approximately -80 mV, a value similar to the average E(h) for Cys/CySS in human plasma. The mechanisms involved in regulation of extracellular E(h) of Cys/CySS are not known, but GSH is released from tissues at rates proportional to tissue GSH concentration, and this released GSH could react with CySS to contribute to maintenance of this balance. The present study was undertaken to determine whether depletion of cellular GSH alters regulation of extracellular Cys/CySS E(h). Decrease of GSH in HT-29 cells by inhibiting synthesis with l-buthionine-[S,R]-sulfoximine showed no effect on the rate of reduction of extracellular CySS to achieve a stable E(h) for Cys/CySS in the culture medium. Limiting Cys and CySS in the culture medium also substantially decreased cellular GSH but resulted in no significant effect on extracellular Cys/CySS E(h). Addition of CySS to these cells showed that extracellular Cys/CySS E(h) approached -80 mV at 4 h while cellular GSH and extracellular GSH/GSSG E(h) recovered more slowly. Together, these results show that HT-29 cells have the capacity to regulate the extracellular Cys/CySS E(h) by mechanisms that are independent of cellular GSH. The results suggest that transport systems for Cys and CySS and/or membranal oxidoreductases could be more important than cellular GSH in regulation of extracellular Cys/CySS E(h).
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Affiliation(s)
- Corinna L Anderson
- Department of Medicine/Pulmonary, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
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Ball RO, Urschel KL, Pencharz PB. Nutritional consequences of interspecies differences in arginine and lysine metabolism. J Nutr 2007; 137:1626S-1641S. [PMID: 17513439 DOI: 10.1093/jn/137.6.1626s] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Differences in lysine and arginine requirements among various species such as omnivores (humans, pigs, rats, dogs), carnivores (cats), herbivores (rabbits, horses), ruminants (cattle), poultry, and fish, are covered in detail in this article. Although lysine is classified as an indispensable amino acid across species, the classification of arginine as either an indispensable or dispensable amino acid is more ambiguous because of differences among species in rates of de novo arginine synthesis. Because lysine is most often the limiting amino acid in the diet, its requirement has been extensively studied. By use of the ideal protein concept, the requirements of the other indispensable amino acids can be extrapolated from the lysine requirement. The successful use of this concept in pigs is compared with potential application of the ideal protein concept in humans. The current dietary arginine requirement varies widely among species, with ruminants, rabbits, and rats having relatively low requirements and carnivores, fish, and poultry having high requirements. Interspecies differences in metabolic arginine utilization and reasons for different rates of de novo arginine synthesis are reviewed in detail, as these are the primary determinants of the dietary arginine requirement. There is presently no dietary requirement for humans of any age, although this needs to be reassessed, particularly in neonates. A thorough understanding of the factors contributing to the lysine and arginine requirements in different species will be useful in our understanding of human amino acid requirements.
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Affiliation(s)
- Ronald O Ball
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, and The Research Institute, The Hospital for Sick Children, Toronto, ON, Canada M5G.
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