Dr. Heather BlewettPrincipal Investigator
Human Nutrition and Immunology, Canadian Centre for Agri-Food Research in Health and Medicine
Dr. Blewett is an AAFC scientist working at the Canadian Centre for Agri-Food Research in Health and Medicine (CCARM). She uses her expertise in human nutrition to perform the clinical trials that are needed to substantiate food health claims for Canadian crops including LDL cholesterol lowering, reduction in postprandial glucose response and increased satiety. Her background in immunology also allows her to focus on the effect of Canadian food products on immune function in the context of chronic diseases (ie. cardiovascular disease, diabetes, obesity).
Why is this work important?
Health claims help increase sales of Canadian crops, promote the development of novel food products, and help consumers make healthier food choices in the grocery aisle.
Dysregulated immune function is a feature of many chronic diseases, including obesity, diabetes and cardiovascular disease. Understanding how and what we eat influences the functioning of the immune system is the key to developing novel food products to support health.
What techniques and equipment are used in this laboratory?
In the lab:
- Flow cytometry
- ex vivo stimulation of immune cells to measure proliferation and cytokine production
- Multi-array electrochemiluminescent assays using MSD imager
- enzyme linked immunosorbant assays
- flurometric/colorimetric assays
- Cobas c111 clinical chemistry autoanalyzer
- High performance liquid chromatography
In the clinic:
- Air displacement plethysmography to measure body composition using the BOD POD
- Blood pressure
- Glucose tolerance tests
- Peripheral artery tonometry using the Endo-PAT2000 system
About Dr. Blewett
Dr. Blewett’s exposure to research started at a young age. Her mother worked as a lab technician in the Department of Anatomy when she was a child. As a consequence, her first exposure to laboratory science was when her mother would bring her in on the weekends to help feed and weigh the rats in her experiments. This first exposure to research inspired Dr. Blewett to follow a career path with the ultimate goal of conducting experiments aimed at improving the health of the population through food.
Dr. Blewett’s research expertise is centred on nutritional immunology. Her PhD explored effects of zinc deficiency on T-cell maturation and function. She went on to work with the leading nutritional immunologist in Canada: Dr. Field. In her lab Dr. Blewett expanded both her nutritional and immunological training by studying the importance of amino acids and fatty acids for intestinal and immune defence against E. coli using a novel piglet model. She also discovered that the trans fat vaccenic acid favourably alters the pro-inflammatory tendency of mesenteric lymphocytes in obesity. As a Post Doctoral Fellow in Peter Zahradka’s lab she had the opportunity to gain valuable experience in clinical trials and the burgeoning field of nutrigeomics.
For more information, contact:
Dr. Heather Blewett
Dr. Blewett’s lab has research projects investigating the effect of polyphenols extracted from berries on T-cell activation in animal models of hypertension and myocardial infarction.
Effect of Barley on Blood Sugar Levels After a Meal
Barley can limit the rise in blood sugar levels after a meal; however there are several factors in food that can be manipulated to optimize its effect on blood sugar. After varying the amount of resistant starch, soluble fibre (β-glucan) and insoluble fibre, we discovered that the β-glucan content had the greatest effect on blood sugar levels after a meal. You can read the results here:
We recently designed a follow-up study to see what dose of β-glucan is needed to limit the rise in blood sugar levels after a meal. You can read more information about the study here: https://www.clinicaltrials.gov/ct2/show/NCT02367989 Recruitment was recently completed, so come back soon to learn about our results.
Pea Studies on Blood Sugar Levels After a Meal
Peas are high in resistant starch, fibre and protein, so we believed that replacing a portion of a high starch food like white rice or instant potato with peas would limit the rise in blood sugar levels after a meal (otherwise known as post-prandial glycaemic response). We have completed a trial comparing the post-prandial glycaemic response of white rice with and without 3 common market classes of peas (Golden: Whole yellow pea; Meadow: Split yellow pea; Striker: Split green pea) and repeated the trial with instant potatoes. We found that replacing just over half of the digestible carbohydrate from rice or instant potatoes with peas does limit the rise in blood sugar levels after a meal. There was no difference between the varieties of peas. The results of these trials were presented at the Canadian Nutrition Society Annual meeting in 2017 http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2017-0134?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed&#.W-DK2WNRdzk and 2018 http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2018-0119?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed#.W-DK9GNRdzk .
We have designed 3 follow-up trials to determine if the same effect is seen when the peas are made into more complex foods (ie. Muffins, chili and soup). We are also interested in whether peas affect appetite, making a person feel fuller for longer, and maybe even eat fewer calories throughout the day. We are still looking for volunteers, so if you would like to learn more about this study, please contact us at: 204-258-1209 or firstname.lastname@example.org
LDL cholesterol lowering effect of ground flaxseed
Dr. Blewett is also investigating the cholesterol-lowering effect of ground flaxseed in volunteers with above optimal LDL cholesterol. This trial is designed as a multi-site, randomized, double-blind, controlled, crossover study. A total of 76 people were recruited at two sites: 1) CCARM (Winnipeg); 2) GI Labs Inc. (Toronto). The overall goal of this study is to fill in the gaps in the clinical data on the cholesterol-lowering effects of ground flaxseed by establishing an effective minimal dose; including male and pre-menopausal women in the sample population, and fully characterizing the nutrient composition of the test foods.
With the rising incidence of overweight and obesity in developed countries, there is an interest in developing food products that may help control appetite and reduce calorie intake. Thirty-eight healthy adults were recruited to participate in our trial with the main objective to determine if consuming snacks made from buckwheat would increase satiety and reduce energy intake. We found that neither buckwheat groats (32 g serving; 141 kcal) nor pita bread made from buckwheat flour (50 g serving; 135 kcal) changed appetite ratings or the amount of calories consumed compared with reference snack products made from corn or rice flour. Here’s a link to the results: http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2017-0295?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed#.W-DMUWNRdzkDr. Heather Blewett has appeared on CTV Morning Live discussing this project: http://winnipeg.ctvnews.ca/ctv-morning-live
LDL cholesterol lowering effect of whole soy
The results are in from a multi-centre trial looking into the cholesterol-lowering effect of whole soy in volunteers with high LDL cholesterol (known as “bad” cholesterol). Dr. Blewett lead the trial at CCARM, in collaboration with Dr. Wolever at GI Labs in Toronto, Dr. Duncan from the Human Nutraceutical Research Unit at the University of Guelph and Dr. Ramdath from the Guelph Research and Development Centre.
To read the scientific research reports from this study, please follow these links:
Manitoba Health Research Council Postdoctoral Fellowship (2009-2011)
Level: Provincial Value: $36 750/year
Dr. Elizabeth Feniak’s Award for Excellence in Technical Writing (2005)
Level: National Value: $500
Holmfidur Kristjansson Graduate Award in Nutrition (1999)
Level: Institutional Value: $2625
Xerox Canada University Education Scholarship (1995-1999)
Level: National Value: $6000
Blewett laboratory would like to gratefully acknowledge the following funding agencies and foundations:
- Agriculture and Agri-Food Canada
- Manitoba Agri-Health Research Network
- Research Manitoba