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Open Access Open Badges Study protocol

The HYPERFlax trial for determining the anti-HYPERtensive effects of dietary flaxseed in newly diagnosed stage 1 hypertensive patients: study protocol for a randomized, double-blinded, controlled clinical trial

Stephanie PB Caligiuri123, Brian Penner4 and Grant N Pierce123*

Author Affiliations

1 Canadian Centre for Agri-food Research in Health and Medicine (CCARM), St. Boniface Hospital Research Centre, 351 Taché Avenue, Winnipeg, MB R2H 2A6, Canada

2 The Institute of Cardiovascular Science, St. Boniface Hospital Research Centre, 351 Taché Avenue, Winnipeg, MB R2H 2A6, Canada

3 Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada

4 Department of Internal Medicine, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada

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Trials 2014, 15:232  doi:10.1186/1745-6215-15-232

Published: 18 June 2014



In 2013 the World Health Organization deemed hypertension as a global crisis as it is the leading risk factor attributed to global mortality. Therefore, there is a great need for effective alternative treatment strategies to combat a condition that affects 40% of adults worldwide. Recently, the FlaxPAD Trial observed a significant reduction in systolic and diastolic blood pressure in hypertensive patients with peripheral arterial disease that consumed 30 g of milled flaxseed per day for one year. However, these patients were already on anti-hypertensive medication. Therefore, there is a need to assess if dietary flaxseed can effectively reduce blood pressure in the absence of peripheral arterial disease and anti-hypertensive medication in newly diagnosed hypertensive patients.


The HYPERFlax Trial is a parallel, superiority, phase II/III, randomized, double-blinded, controlled clinical trial. St. Boniface Hospital and the Health Sciences Centre of Winnipeg, Canada, will recruit 100 participants newly diagnosed with stage 1 hypertension who have yet to be administered anti-hypertensive medication. Participants will be randomly allocated with a 1:1 ratio into a flaxseed or control group and provided food products to consume daily for six months. At baseline, two, four, and six months, participant assessments will include the primary outcome measure, averaged automated blood pressure, and secondary measures: 24-hour food recall, international physical activity questionnaire, anthropometrics, and blood and urine sampling for biochemical analysis. Plasma will be assessed for lipids, metabolomics profiling, and molecules that regulate vascular tone. Urine will be collected for metabolomics profiling. With an estimated dropout rate of 20%, the trial will have a power of 0.80 to detect differences between groups and across time, out of an effect size of 0.7 (SD) at an α level of 0.05.


This trial will determine if dietary flaxseed is efficacious over six months as an anti-hypertensive therapy in subjects newly diagnosed with hypertension. If flaxseed can effectively reduce blood pressure as a monotherapy, then flaxseed will provide individuals on a global basis with a cost-effective food-based strategy to control hypertension.

Trial registration

NCT01952340, Registered 24 September 2013.

Hypertension; Flaxseed; Blood pressure; Nutrition; Alpha linolenic acid