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How SickKids research is unravelling the science of protein quality in plant-based foods
5 minute read

How SickKids research is unravelling the science of protein quality in plant-based foods


As the world moves to a more plant-based diet, a SickKids dietitian and researcher is contributing to an international protein quality database.

As leaders in health and climate change recommend a more plant-based diet, an increasing number of people are shifting away from animal protein. While proteins exist in plant-based foods, the amino acids they contain are lower in plants than in animal foods and the body’s ability to absorb and retain these nutrients varies and can lead to poorer growth and malnutrition, particularly in nations that heavily rely on plant foods. So, how can a change to plant-based proteins be made in a healthy way?

Dr. Glenda Courtney-Martin Dr. Glenda Courtney-Martin works in her lab with her research team in the background.
Dr. Glenda Courtney-Martin

At The Hospital for Sick Children (SickKids), Dr. Glenda Courtney-Martin is an international expert in protein quality work, helping to identify the amount of amino acids available in plant proteins and contribute data to an international protein quality database at the International Atomic Energy Agency (IAEA).

“Proteins are essential to our development and help protect us from infections. While there are over one million vegetarians in Canada, so many more people who want to become vegetarians do not know how to make that change safely,” says Courtney-Martin, a Senior Associate Scientist in the Translational Medicine program and Clinical Dietitian in the Department of Clinical Dietetics.

Dr. Glenda Courtney-Martin measures nutrients on a scale in the SickKids metabolic kitchen.

“Knowledge of protein quality of plant foods helps us plan diets with the appropriate balance of plant-proteins to ensure people’s health needs are being met.”

Getting the right proteins

Proteins are comprised of 20 amino acids, which are essential to normal body function. In her lab at the SickKids Research Institute, Courtney-Martin runs one of only three labs in the world that use stable isotope methods to measure how people absorb and use amino acids from foods.

While other methods of protein quality are available, she notes they are unsuitable for vulnerable populations, such as children, since measurements may require invasive procedures such as blood draws.

In comparison, the stable isotope method employed by Courtney-Martin and her team requires only a breath sample after eating a sample food. By measuring the stable isotope labelled carbon in breath, the research team can determine how well the amino acids are absorbed and used by the body. This approach also only requires a deficient diet for one day, making it suitable for children and other vulnerable populations who may be more sensitive to nutritional changes.

Dr. Glenda Courtney-Martin measures nutrients at a bench in the SickKids metabolic kitche.
Dr. Glenda Courtney-Martin splits her time between the SickKids Research Institute and the metabolic kitchen.

Growing global solutions

As one of the few experts in the world conducting protein quality work, Courtney-Martin's days are often spent running across the SickKids campus between her lab space in the Peter Gilgan Centre for Research and Learning, the metabolic kitchen in the hospital where she and her team prepare metabolic diets, and her office where she works with patients in the Group for Improvement of Intestinal Function and Treatment (GIFT) program to support the treatment and research of children with intestinal failure. But her work does not end there. Courtney-Martin is also conducting research on amino acid requirements in newborns, fed by a method called total parenteral nutrition, which delivers nutrition to infants in the Neonatal Intensive Care Unit at SickKids via a vein. This research is funded by the Canadian Institutes of Health Research (CIHR).

As she continues to provide patient care and investigate child nutrition, Courtney-Martin’s aims to use her work to develop solutions to address global malnutrition.

“Understanding protein requirements is a public health issue,” says Courtney-Martin. “Whether someone is malnourished from famine or poverty, whether they want to reduce their environmental footprint, or whether they are simply looking for plant-based alternatives, understanding protein quality will contribute to a healthier and safer plant-based world.”

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