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Plasma fatty acid changes following consumption of dietary oils containing n-3, n-6, and n-9 fatty acids at different proportions: preliminary findings of the Canola Oil Multicenter Intervention Trial (COMIT)

Vijitha K Senanayake16, Shuaihua Pu1, David A Jenkins2, Benoît Lamarche3, Penny M Kris-Etherton4, Sheila G West45, Jennifer A Fleming4, Xiaoran Liu4, Cindy E McCrea5 and Peter J Jones1*

Author Affiliations

1 Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, 196 Innovation Drive, SmartPark, Winnipeg, MB R3T 6C5, Canada

2 St. Michaels Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada

3 Institute of Nutrition and Functional Foods, Pavillon des Services, Université Laval, Suite 1705, 2440 Hochelaga Blvd, Québec, QC G1V 0A6, Canada

4 Department of Nutritional Sciences, Pennsylvania State University, 110 Chandlee Laboratory, University Park, PA 16802, USA

5 Department of Biobehavioral Health, Pennsylvania State University, 219 Biobehavioral Health Building, University Park, PA 16802, USA

6 Current address: Phenomenome Discoveries Inc, Saskatoon, Saskatchewan, Canada

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Trials 2014, 15:136  doi:10.1186/1745-6215-15-136

Published: 23 April 2014



The Canola Oil Multicenter Intervention Trial (COMIT) was a randomized controlled crossover study designed to evaluate the effects of five diets that provided different oils and/or oil blends on cardiovascular disease (CVD) risk factors in individuals with abdominal obesity. The present objective is to report preliminary findings on plasma fatty acid profiles in volunteers with abdominal obesity, following the consumption of diets enriched with n-3, n-6 and n-9 fatty acids.


COMIT was conducted at three clinical sites, Winnipeg, Manitoba, Canada, Québec City, Québec, Canada and University Park, Pennsylvania, United States. Inclusion criteria were at least one of the followings: waist circumference (≥90 cm for males and ≥84 cm for females), and at least one other criterion: triglycerides ≥1.7 mmol/L, high density lipoprotein cholesterol <1 mmol/L (males) or <1.3 mmol/L (females), blood pressure ≥130 mmHg (systolic) and/or ≥85 mmHg (diastolic), and glucose ≥5.5 mmol/L. Weight-maintaining diets that included shakes with one of the dietary oil blends were provided during each of the five 30-day dietary phases. Dietary phases were separated by four-week washout periods. Treatment oils were canola oil, high oleic canola oil, high oleic canola oil enriched with docosahexaenoic acid (DHA), flax oil and safflower oil blend, and corn oil and safflower oil blend. A per protocol approach with a mixed model analysis was decided to be appropriate for data analysis.


One hundred and seventy volunteers were randomized and 130 completed the study with a dropout rate of 23.5%. The mean plasma total DHA concentrations, which were analyzed among all participants as a measure of adherence, increased by more than 100% in the DHA-enriched phase, compared to other phases, demonstrating excellent dietary adherence.


Recruitment and retention strategies were effective in achieving a sufficient number of participants who completed the study protocol to enable sufficient statistical power to resolve small differences in outcome measures. It is expected that the study will generate important data thereby enhancing our understanding of the effects of n-3, n-6, and n-9 fatty acid-containing oils on CVD risks.

Trial registration NCT01351012.

Cardiovascular diseases; Metabolic syndrome; Plasma fatty acids; Serum lipids; Lipoproteins; Canola oil; DHA; Randomized controlled clinical trial