Glenda Courtney-Martin

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Other Academic and Clinical Appointments

Health Systems Research Scientist, Department of Clinical Dietetics, The Hospital for Sick Children (2018 - present)

Health Clinician Scientist, The Hospital for Sick Children (2017 - present)

Associate Scientist, Research Institute, The Hospital for Sick Children (2016 - present)

Health Clinician Scientist, Health Clinician Scientist Community of Practice, The Hospital for Sick Children (2016 - present)

Assistant Professor, Faculty of Kinesiology and Physical Education, University of Toronto (2014 - present)

Clinical Dietitian, The Hospital for Sick Children (1999 - present)

At a Glance

• Dr. Courtney-Martin’s research focus is on protein and amino acid requirement and metabolism through the lifespan and evaluation of dietary protein quality of foods for human nutrition.

About Dr. Courtney-Martin

Dr. Glenda Courtney-Martin obtained her undergraduate degree in Nutrition from Ryerson University and her Masters and PhD from the University of Toronto. She is a member of the College of Dietitians of Ontario, having completed her Dietetic Internship at St. Michael’s Hospital in Toronto. Currently, Dr. Courtney-Martin is a Clinical Dietitian and Health Clinician Scientist at The Hospital for Sick Children in Toronto. She is Associate Scientist in the Research Institute, Program in Physiology and Experimental Medicine and Assistant Professor, Department of Nutritional Sciences & Faculty of Kinesiology & Physical Education, University of Toronto. Dr. Courtney-Martin’s research focus is on protein and amino acid requirement and metabolism through the lifespan and evaluation of dietary protein quality of foods for human nutrition. Her early work focused on the requirement and metabolism of the sulphur amino acids in the total parenteral fed (TPN) post surgical human neonate. She demonstrated that the sulphur amino acid content of current commercial TPN solutions is too high and could be a contributor to TPN related liver disease observed in neonates and young children on long-term TPN. Her current work include the conduction of a number of studies in children and older adults to estimate the requirement of several indispensable amino acids and to validate the higher requirement estimate for protein proposed by her research group. In addition, she is actively evaluating the dietary protein quality of cereal grains to meet human nutrition needs. Dr. Courtney-Martin is the recipient of a CIHR Project Grant for her work titled: Evaluating the dietary protein quality of cereal grains to meet human nutrition needs by measuring the metabolic availability of the most limiting amino acid: lysine. She is also co-applicant on a CIHR Operating Grant for the determination of amino acid requirement throughout the lifespan.

Research Synopsis

Dr. Courtney-Martin's research currently examines the application of the indicator amino oxidation, combined with slope ratio technique for the determination of protein quality of foods for human consumption. She is also currently evaluating protein quality of a number of cereal grains and pulses in young, healthy adult men. Protein quality evaluation assesses the capacity of food proteins to meet the essential amino acid needs of the body. Food protein quality depends on essential amino acid composition and bioavailability. The Food and Agricultural Organization recommends that amino acids be treated as individual nutrients for protein quality evaluation, and the data for bioavailability of individual amino acids be presented in food tables. They also issued an urgent call for determination of amino acid bioavailability in human foods using humans, and pigs which is the best non-primate model for application to humans. Ileal digestibility - the proportion of amino acid intake that has disappeared from the digestive tract - is the standard measure of amino acid bioavailability. It is measured by sampling digesta from the terminal ileum and thus too invasive for routine application in humans. Dr. Courtney-Martin's group recently adapted the minimally invasive, stable isotope based indicator amino acid oxidation method to measure amino acid bioavailability first in pigs and now in humans. They actively studying the protein quality of a number of cereal grains and pulses in healthy young men using the indicator amino acid oxidation method.

Additionally, Dr. Courtney-Martin's research examines protein and amino acid requirements across the lifespan with emphasis on neonates on total parenteral nutrition and adult >60 years. Current commercial amino acid solutions used for feeding neonates on total parenteral nutrition (TPN) are based on approximations rather than scientifically derived estimates. Too little or too much amino acids are harmful to neonates. Dr. Courtney-Martin's group began a series of studies defining amino acid requirements in TPN fed neonates and are currently working to complete the requirements all the essential and conditionally essential amino acids. This work will provide the data needed to design an appropriate amino acid solution for feeding neonates requiring TPN. In addition to their neonatal studies, Dr. Courtney-Martin's team is currently doing studies on amino acid requirement in the elderly. The protein and amino acid requirement of the elderly is not known. Current protein and amino acid recommendations for the elderly are based on data from young adult studies. Worldwide, the population is getting older. Aging is accompanied by loss of muscle mass called sarcopenia, which leads to loss of independence and increased health care cost. Protein and amino acids are the most important nutritional factors to prevent loss of muscle mass. Considering recent Canada’s Food Guide recommendations to increase intake of plant foods for improved health and environmental sustainability, it is important to determine amino acid requirement for older adults directly so we could understand if older adults are able to meet amino acid and protein needs on a plant-based diet. Dr. Courtney-Martin's group recently found that the protein recommendations for the older adults are underestimated by about 30%. In addition, they found that leucine, which has a central role in initiating protein synthesis, has a requirement in older adults which is double that observed in young adults. Dr. Courtney-Martin and her team are working to complete the requirements for the remaining essential amino acids in older adults.

Recent Awards and Distinctions (Selected)

Excellence in Clinical Dietetics Award, The Hospital for Sick Children (2019)

National and International Committee Memberships (Current)

Member, Clinical Advisory Committee, Canadian Nutrition Society (2021 - present)

Member, Guideline Committee, Group for the Improvement of Gastrointestinal Function and Treatment (2009 - present)

Recent Publications

1. So S, Patterson C, Betts Z, Belza C, Courtney-Martin G, Avitzur Y, Wales PW. Muscle Strength, Agility and Body Composition in Children with Intestinal Failure on Parenteral Nutrition. J Pediatr Gastroenterol Nutr. 2022 Jul 13. doi: 10.1097/MPG.0000000000003553. Epub ahead of print. PMID: 35830733.
2. Rafii M, Pencharz PB, Boileau K, Ball RO, Tomlinson C, Elango R, Courtney-Martin G. Metabolic Availability of Methionine Assessed Using Indicator Amino Acid Oxidation Method is Greater when Cooked Lentils and Steamed Rice Are Combined in Healthy Young Men. J Nutr. 2022 Feb 26:nxac049. doi: 10.1093/jn/nxac049. Epub ahead of print. PMID: 35218191.
3. Paoletti A, Fakiha A, Tul-Noor Z, Pencharz PB, Levesque CL, Ball RO, Kong D, Elango R, Courtney-Martin G. Bioavailable Lysine Assessed Using the Indicator Amino Acid Oxidation Method in Healthy Young Males is High when Sorghum is Cooked by a Moist Cooking Method. J Nutr. 2021 Dec 6:nxab410. doi: 10.1093/jn/nxab410. Epub ahead of print. PMID: 34871427.
4. Yanchis D, Belza C, Harrison D, Wong-Sterling S, Kean P, So S, Patterson C, Wales PW, Avitzur Y, Courtney-Martin G. Normal anthropometry does not equal normal body composition in pediatric intestinal failure. JPEN J Parenter Enteral Nutr. 2021 Sep 12. doi: 10.1002/jpen.2265. Epub ahead of print. PMID: 34510469.
5. Courtney-Martin G. False equivalence or fake news: is a peanut really an egg? J Nutr. 2021 May 11;151(5):1055-1056. doi: 10.1093/jn/nxab051. PMID: 33830240.
6. Schmidt ML, Wendel D, Horslen SP, Lane ER, Brandão LR, Gottschalk E, Belza C, Courtney-Martin G, Wales PW, Avitzur Y. Secondary Anticoagulation Prophylaxis for Catheter-Related Thrombosis in Pediatric Intestinal Failure: Comparison of Short- Vs Long-Term Treatment Protocols. JPEN J Parenter Enteral Nutr. 2021 Sep;45(7):1432-1440. doi: 10.1002/jpen.2055. Epub 2021 Jan 7. PMID: 33616995; PMCID: PMC8191809.
7. Szwiega S, Pencharz PB, Rafii M, Lebarron M, Chang J, Ball RO, Kong D, Xu L, Elango R, Courtney-Martin G. Dietary leucine requirement of older men and women is higher than current recommendations. Am J Clin Nutr. 2021 Feb 2;113(2):410-419. doi: 10.1093/ajcn/nqaa323. PMID: 33330915; PMCID: PMC7851820.
8. Ennis MA, Ong AJ, Lim K, Ball RO, Pencharz PB, Courtney-Martin G, Elango R. Dietary Aromatic Amino Acid Requirements During Early and Late Gestation in Healthy Pregnant Women. J Nutr. 2020 Dec 10;150(12):3224-3230. doi: 10.1093/jn/nxaa317. PMID: 33188409; PMCID: PMC7726121.
9. Caballero K, Mandal R, Pratap-Singh A, Kitts DD, Ball RO, Pencharz PB, Courtney-Martin G, Elango R. Lysine Bioavailability in School-Age Children Consuming Rice Is Reduced by Starch Retrogradation. J Nutr. 2020 Dec 10;150(12):3208-3215. doi: 10.1093/jn/nxaa276. PMID: 33025006.
10. Fakiha A, Tul-Noor Z, Paoletti A, Pencharz PB, Ball RO, Levesque CL, Elango R, Courtney-Martin G. Bioavailable Lysine, Assessed in Healthy Young Men Using Indicator Amino Acid Oxidation, is Greater when Cooked Millet and Stewed Canadian Lentils are Combined. J Nutr. 2020 Oct 12;150(10):2729-2737. doi: 10.1093/jn/nxaa227. PMID: 32840580.

Current Lab Members (within the Department of Nutritional Sciences)

Alyssa Paoletti - PhD student

Sylwia Szwiega - PhD student

Elizabeth Haliburton - MSc student

Yuxuan Li - MSc student