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Dr. Heather Blewett

Dr. Heather Blewett

Principal Investigator
Human Nutrition and Immunology, Canadian Centre for Agri-Food Research in Health and Medicine

Research Focus

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), infectious disease and allergy.

Pea Study

Dr. Blewett is looking for volunteers to participate in a study testing the effect of peas on blood sugar levels after a meal. The overall goal of this study is to provide the scientific evidence necessary to substantiate a health claim that replacing rice or potato with peas results in a lower blood sugar rise. To learn more about this study, please contact us at: 204-258-1209 or peas@sbrc.ca

The Manitoba Personalized Lifestyle Research Program (TMPLR)

Dr. Blewett is a team member of the TMPLR project, whose overall objective is to bring together an interdisciplinary team to implement a cross-sectional study to identify the complex interactions that exist between lifestyle, genetics, and gut microbiota and explore how these relate to risk factors for chronic conditions in Manitoba. Her focus is on immune function and how its dysregulation is related to lifestyle factors, genetics and gut microbiota. Please visit www.tmplr.ca for more information.

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.

Snack Study

Recruitment is complete with data analysis ongoing for a study investigating the effect of high protein or high fibre snacks on appetite control. The overall goal is to provide the scientific evidence necessary to substantiate a health claim that a serving of these snacks is more filling and for longer than a typical snack. This will assist consumers who want to maintain a healthy body weight select a snack that can help control their appetite.

Dr. 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 leads 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:

http://jn.nutrition.org/content/145/12/2665.long
http://www.sciencedirect.com/science/article/pii/S0963996915301800

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.

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
  • RNA extraction for microarrays/RT-PCR
  • Gas chromatography
  • 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 centered 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 defense against E. coli using a novel piglet model. She also discovered that the trans fat vaccenic acid favorably 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
Email: hblewett@sbrc.ca

Whole soy flour incorporated into a muffin and consumed at 2 doses of soy protein does not lower LDL cholesterol in a randomized, double-blind controlled trial of hypercholesterolemic adults. Padhi EM, Blewett HJ, Duncan AM, Guzman RP, Hawke A, Seethararaman K, Tsao R, Wolever TM, Ramdath DD. J Nutr. 2015 Dec; 145(12):2665-74.

Liking of soy flour muffins over time and the impact of a health claim on willingness to consume. Padhi EM, Ramdath DD, Carson SJ, Hawke A, Blewett HJ, Wolever TM, Vella D, Seetharaman K, Duizer LM, Duncan AM. Food Research International 2015 Nov;77(3):491-7.

A double-blind randomised controlled trial testing the effect of a barley product containing varying amounts and types of fibre on the postprandial glucose response of healthy volunteers. Ames N, Blewett H, Storsley J, Thandapilly SJ, Zahradka P, Taylor C. Br J Nutr. 2015 May 14;113(9):1373-83.

The reduced proportion of New splenic T-cells in the zinc-deficient growing rat is not due to increased susceptibility to apoptosis. Blewett HJ, Mohankumar SK, Rech L, Rector ES, Taylor CG. Immunobiology 2014 Aug;219(8):602-10.

Daily non-soy legume consumption reverses vascular impairment due to peripheral artery disease. Zahradka P, Wright B, Weighell W, Blewett H, Baldwin A, O K, Guzman RP, Taylor CG. Atherosclerosis 2013 Oct; 230(2):310-4.

Consumption of buckwheat modulates the post-prandial response of selected gastrointestinal satiety hormones in individuals with type 2 diabetes mellitus. Stringer DM, Taylor CG, Appah P, Blewett H, Zahradka P. Metabolism 2013 Jul;62(7):1021-31.

Dietary zinc deficiency in rodents: Effects of T-cell development, maturation and phenotypes. Blewett HJ, Taylor CG. Nutrients. 2012 Jun; 4(6): 449-66.

Dietary flaxseed oil reduces adipocyte size, adipose monocyte chemoattractant protein-1 levels and T-cell infiltration in obese, insulin-resistant rats. Baranowski M, Enns J, Blewett H, Yakandawal U, Zahradka P, Taylor CG. Cytokine. 2012 Aug; 59(2): 382-391.

Human health benefits of vaccenic acid. Field CJ, Hosea Blewett H, Proctor S, Vine D. Appl Physiol Nutr Metab. 2009 Oct; 34(5):979-91.

Vaccenic acid favorably alters immune function in obese JCR:LA-cp rats. Blewett HJ, Gerdung CA, Ruth MR, Proctor SD, Field CJ Br J Nutr. 2009 Aug;102(4):526-36.

Relationship between abnormal sperm morphology induced by dietary zinc deficiency and lipid composition in testis of growing rats. Merrells KJ, Blewett H, Jamieson JA, Taylor CG, Suh M Br J Nutr. 2009 Jul;102(2):226-32.

Exploring the mechanisms behind S-adenosylmethionine (SAMe) in the treatment of osteoarthritis. Hosea Blewett HJ. Crit Rev Food Sci Nutr. 2008 May;48(5):458-63s.

Altered ex vivo cytokine production in zinc-deficient, pair-fed and marginally zinc-deficient growing rats is independent of serum corticosterone concentrations. Hosea Blewett HJ, Rector ES, Taylor CG. Br J Nutr. 2008 Oct;100(4):820-8.

Dietary zinc deficiency lowers the proportions of splenic CD90+ (Thy-1+) B-cells and late thymic emigrant T-cells in growing rats. Hosea HJ, Rector ES, Taylor CG. Br J Nutr. 2007 Dec;98(6):1108-11.

Age-related changes in p56lck protein levels and phenotypic distribution of T lymphocytes in young rats. Hosea HJ, Rector ES, Taylor CG. Clin Dev Immunol. 2005 Mar;12(1):75-84.

Dietary repletion can replenish reduced T cell subset numbers and lymphoid organ weight in zinc-deficient and energy-restricted rats. Hosea HJ, Rector ES, Taylor CG. Br J Nutr. 2004 May;91(5):741-7.

Zinc-deficient rats have more limited bone recovery during repletion than diet-restricted rats. Hosea HJ, Taylor CG, Wood T, Mollard R, Weiler HA. Exp Biol Med (Maywood). 2004 Apr;229(4):303-11.

Zinc-deficient rats have fewer recent thymic emigrant (CD90+) T lymphocytes in spleen and blood. Hosea HJ, Rector ES, Taylor CG. J Nutr. 2003 Dec;133(12):4239-42

Chapters/Contributions to Collective Work

Does supplemental conjugated linoleic acid (CLA) or high dietary CLA reduce the risk of pregnancy-induced hypertension (PIH)? Blewett HJ for Dietitians of Canada. Practice question In: Practice-based Evidence in Nutrition [PEN]. August 04, 2009. Available from: http://www.dieteticsatwork.com/PEN/index.asp . Access only by subscription.

Does a high dietary conjugated linoleic acid (CLA) intake reduce blood glucose levels in pregnant women with gestational diabetes? Blewett HJ for Dietitians of Canada. Practice question In: Practice-based Evidence in Nutrition [PEN]. August 04, 2009. Available from: http://www.dieteticsatwork.com/PEN/index.asp . Access only by subscription.

Does the conjugated linoleic acid (CLA) content of the diet alter fetal development (length of gestation, birth weight and length)? Blewett HJ for Dietitians of Canada. Practice question In: Practice-based Evidence in Nutrition [PEN]. August 04, 2009. Available from: http://www.dieteticsatwork.com/PEN/index.asp . Access only by subscription.

Does supplemental conjugated linoleic acid (CLA) or high dietary CLA intake reduce the risk of developing breast cancer, slow the progression or aid in treatment of existing breast cancer? Blewett HJ for Dietitians of Canada. Practice question In: Practice-based Evidence in Nutrition [PEN]. August 04, 2009. Available from: http://www.dieteticsatwork.com/PEN/index.asp . Access only by subscription.

Does supplemental conjugated linoleic acid (CLA) or high dietary CLA reduce body fat/body weight in people who are overweight/obese? Blewett HJ for Dietitians of Canada. Practice question In: Practice-based Evidence in Nutrition [PEN]. August 04, 2009. Available from: http://www.dieteticsatwork.com/PEN/index.asp . Access only by subscription.

Does the conjugated linoleic acid (CLA) content of a breastfeeding woman’s diet affect the fat composition of her breastmilk? Blewett HJ for Dietitians of Canada. Practice question In: Practice-based Evidence in Nutrition [PEN]. August 04, 2009. Available from: http://www.dieteticsatwork.com/PEN/index.asp . Access only by subscription.

The immunological components of human milk. Hosea Blewett HJ, Cicalo MC, Holland CD, Field CJ. Adv Food Nutr Res. 2008;54:45-80.


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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

Funding for research program has been provided by Growing Forward II from Agriculture and Agri-Food Canada.

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