Canola-Mediterranean Diet Study in T2DM

Canola Enriched Mediterranean Type Weight Loss Diet in Type 2 Diabetes

The purpose of the study is to assess whether a Mediterranean-type weight-loss diet, enriched with canola oil, high in plant protein, and low in carbohydrates will produce blood sugar control, reduce coronary heart disease (CHD) risk factors and maximize weight loss, better than conventional higher carbohydrate diets in overweight diabetic patients.

Study Overview

• Status: Completed
• Conditions: Cardiovascular Diseases; Obesity; Overweight; Type 2 Diabetes
• Intervention / Treatment: Behavioral: A canola oil enriched mediterranean diet; Behavioral: A high wheat fiber diet

Detailed Description

The investigators plan to assess the effects of increasing both canola oil and plant protein foods while reducing carbohydrate intake in the context of a Mediterranean type diet on weight loss, glycemic control and cardiovascular risk factors in type 2 diabetes.

Obesity rates in Western nations have shown a dramatic rise in the last 20 years and diabetes rates have doubled, a trend which is predicted to be repeated over the next 20 years. In Canada the predicted cost to the healthcare system in only 7 years will rise to $17 billion. Weight loss diets (such as Atkins, Eddies, South Beach and Zone) emphasizing carbohydrate restriction have become increasingly popular for the prevention and treatment of diabetes. As a result, lower carbohydrate diets are being selected by health conscious members of the general population including those with diabetes. Because such diets in effect promote a high intake of protein from animal sources, even in the presence of weight loss, serum cholesterol levels rise due to increased cholesterol and saturated fat intake; and a further rise in serum lipids is likely to occur in the long term when weight loss has ceased. On the other hand, lower carbohydrate dietary patterns that are higher in plant rather than animal fat and proteins have been associated with improved blood lipids and reduced risk of heart disease and type 2 diabetes.

The investigators have therefore planned a study in which a weight reducing low carbohydrate, Mediterranean type diet that is high in plant proteins and canola oil will be compared to a weight reducing high cereal fibre diet in a 3 month study. 150 overweight and obese participants with type 2 diabetes will be randomized to one of 2 treatments.

Study visits will be as follows: weeks -2, 0 (for randomization), 2, 4, 8, 10 and 12. Body measurements, blood pressure and blood samples will be taken at each visit except week 2. The week 2 visit will be mainly for reinforcement of dietary advice; also body weight will be measured and blood drawn for fast glucose and HbA1c. Diet records will be reviewed at all visits. 24 hour urine samples will be collected at week 0 and week 12.

On completion of the 12 week study, participants will be given the option of continuing on the same diet or trying the opposite diet for a further 12 weeks. Visits will be every 4 weeks for a total of 3 visit. Body measurements, blood pressure and blood samples will be taken during these visits as in the initial 12 week study.

• Study Type: Interventional
• Enrollment (Actual): 164
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Manitoba
    • Winnipeg, Manitoba, Canada, R3T 6C5
      • Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba
  • Ontario
    • Toronto, Ontario, Canada, M5C 2T2
      • Risk Factor Modification Centre, St. Michael's Hospital
  • Quebec
    • Quebec City, Quebec, Canada, G1V 4G2
      • Institute of Nutraceuticals and Functional Foods, Laval University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Men and women with type 2 diabetes diagnosed for more than 6 months
• BMI >27 (non-Asians); BMI >25 (Asians)
• HbA1c between 6.5% and 8.5% at screening, and at the preparation visit before starting diet
• on a stable prescribed dose of oral diabetes medication for at least 2 months
• on a stable dose of lipid medication for at least 2 weeks, if prescribed
• on a stable dose of blood pressure medication for at least 1 week, if prescribed
• have a family physician
• can keep written food records, with the use of a digital scale

Exclusion Criteria:

Individuals with the following characteristics/conditions will be excluded

• on insulin
• on steroids
• on warfarin (Coumadin)
• GI disease (gastroparesis, celiac, colitis, Crohn's disease, Inflammatory Bowel Syndrome)
• history of cancer, except non-melanoma skin cancer (basal cell, squamous cell)
• major cardiovascular event (stroke, myocardial infarction) in past 6 months
• major surgery in past 6 months
• major debilitating disorder
• liver disease (AST or ALT> 3x the upper limit of normal) except non-alcoholic fatty liver (NAFL) disease or non-alcoholic steatohepatitis (NASH).
• hepatitis B or C
• renal failure (creatinine > 150 mmol/L)
• serum triglycerides >4.5mmol/L
• acute or chronic infections (bacterial or viral)
• chronic inflammatory diseases (e.g. lupus, ulcerative colitis)
• blood pressure >145/90, unless approved by their family physician
• alcohol consumption >2 drinks/d
• food allergies to wheat, canola, or other study food components
• any condition determined by the investigators to make the subject unsuitable for the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: A canola oil enriched mediterranean diet; Participants will be advised to consume, a low-carbohydrate diet (26-32% of calories), high in vegetable protein (28-32%) and fat (41-45%) with canola as the major component (10%). Carbohydrate sources will feature viscous fiber-containing foods (including psyllium cereal, oats and barley) and low-starch vegetables (emphasizing okra and eggplant) for the relatively limited amount of carbohydrate.	Behavioral: A canola oil enriched mediterranean diet; The diet will be provided at 60% of calories estimated for stable body weight to encourage weight loss. A high protein canola oil-enriched test bread will be provided as a supplement.; Other Names: A mediterranean weight-reducing diet emphasizing canola oil; Eco-Atkins diet; Low carbohydrate dietary portfolio
Active Comparator: A high wheat fiber diet; Participant will be advised to consume a high carbohydrate diet (58% carbohydrate, 16% protein and 25% fat) emphasizing whole wheat/whole grain cereals and increased high fiber alternatives, with fruits and vegetables.	Behavioral: A high wheat fiber diet; The diet will be provided at 60% of calories estimated for stable body weight to encourage weight loss. A whole wheat control bread will be provided as a supplement to participants; Other Names: DASH-type diet

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
change in HbA1c	The baseline HbA1c will be the average HbA1c of weeks -2 and week 0. The end HbA1c will be the average HbA1c of weeks 8, 10 and 12. Change will be the difference between the end and baseline values	Measured at weeks -2, 0, and then at weeks 8, 10 and 12

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in body weight		baseline (week 0) and end (week 12)
blood glucose		At weeks 0, 2, 4, 8, 10 and 12
Serum lipids: total cholesterol, LDL-chol, HDL-chol and Triglycerides		At weeks 0, 4, 8, 10 and 12
Blood pressure		At weeks 0, 4, 8, 10 and 12
24-hour Ambulatory blood pressure profile	Measurement will be done using a non-invasive SpaceLabs 90217 Ambulatory BP monitor	At weeks -1 and 12
diet history	7-day food records brought in at weeks 0, 2, 4, 8, 10 and 12 will be analyzed for macro and micro nutrient intakes.	At weeks 0, 2, 4, 8, 10 and 12
C-reactive protein		At weeks 0 and 12
Cholesterol absorption	This is an optional sub-study that will be carried out prior to the first and last weeks of the 12 week study. On day 1 (a Monday) of the week -1 and last weeks of the study after an overnight 12hr fast, blood will be drawn and participants will be asked to ingest 75mg of the stable carbon isotope [3, 4-13C] cholesterol dissolved in 5g of margarine and spread on half of an English muffin. Subsequent blood draws will be taken after an overnight 12hr fast, at 48 h (a Wednesday) and 72 h (a Thursday) after ingestion of the labeled cholesterol.	At weeks -1 and 12
change in LDL particle size	LDL particle size at weeks 0 and 12 will be determined by assessing their electrophoretic characteristics obtained by non-denaturing polyacrylamide gradient (2-16%) gel electrophoresis of serum	Weeks 0 and 12
urinary analyses	24 hr urine samples will be analyzed for creatinine, urea, C-peptide, minerals, electrolytes and other dietary biomarkers	week 0 and week 12

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Satiety	Using a 9-point bipolar semantic scale where -4 is extremely hungry, 0 is neutral and +4 is uncomfortably full, participants will rate their overall feeling of satiety for the previous week.	at weeks 0, 2, 4, 8, 10 and 12
Taste (palatability) of the study diets, breads and other supplements given	Using a scale of 1 (strongly dislike) to 10 (like very much), participants will rate the taste (palatability) of the study diet and supplements including study breads, vegan 'meats' and egg products.	At weeks 2, 4, 8, 10 and 12
The Medical Outcomes Study 36-Item Short Form Questionnaire (SF-36)	Survey on quality of life	At weeks 0 and 12
Genetic whole genome testing	One time sample collection of buffy coat (from white cells) for future study on gene, diet and chronic disease relationship.	Week 0 or any other time point
complete blood count (CBC)	Health check at start and end of study	Week 0 and week 12
Renal function test	Health check at start and end of study	week 0 and week 12
Liver function test	Health check at start and end of study	week 0 and week 12
Prostatic specific antigen (PSA)	Male participants will undergo this test.	week 0 and week 12
sustainability of diet	using a scale of 1 (study diet will be very difficult to sustain) to 10 (study diet will be very easy to sustain) participants will assess how sustainable their assigned diet will be on a long-term basis.	week 10 and week 12
Testosterone level	Male participants will undergo this test	week 0 and week 12
Estradiol level	Female participants will undergo this test	week 0 and week 12

Collaborators and Investigators

• Sponsor: Unity Health Toronto
• Collaborators: University of Manitoba; University of Toronto; Laval University; Canola Council of Canada
• Investigators: Study Director: Cyril Kendall, PhD, University of Toronto; Study Director: Vladimir Vuksan, PhD, Unity Health Toronto

Publications and helpful links

General Publications

• Shai I, Schwarzfuchs D, Henkin Y, Shahar DR, Witkow S, Greenberg I, Golan R, Fraser D, Bolotin A, Vardi H, Tangi-Rozental O, Zuk-Ramot R, Sarusi B, Brickner D, Schwartz Z, Sheiner E, Marko R, Katorza E, Thiery J, Fiedler GM, Bluher M, Stumvoll M, Stampfer MJ; Dietary Intervention Randomized Controlled Trial (DIRECT) Group. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med. 2008 Jul 17;359(3):229-41. doi: 10.1056/NEJMoa0708681. Erratum In: N Engl J Med. 2009 Dec 31;361(27):2681.
• Jenkins DJ, Wong JM, Kendall CW, Esfahani A, Ng VW, Leong TC, Faulkner DA, Vidgen E, Greaves KA, Paul G, Singer W. The effect of a plant-based low-carbohydrate ("Eco-Atkins") diet on body weight and blood lipid concentrations in hyperlipidemic subjects. Arch Intern Med. 2009 Jun 8;169(11):1046-54. doi: 10.1001/archinternmed.2009.115. Erratum In: Arch Intern Med. 2009 Sep 14;169(16):1490.
• Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem. 1972 Jun;18(6):499-502. No abstract available.
• Sacks FM, Bray GA, Carey VJ, Smith SR, Ryan DH, Anton SD, McManus K, Champagne CM, Bishop LM, Laranjo N, Leboff MS, Rood JC, de Jonge L, Greenway FL, Loria CM, Obarzanek E, Williamson DA. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med. 2009 Feb 26;360(9):859-73. doi: 10.1056/NEJMoa0804748.
• Alhassan S, Kim S, Bersamin A, King AC, Gardner CD. Dietary adherence and weight loss success among overweight women: results from the A TO Z weight loss study. Int J Obes (Lond). 2008 Jun;32(6):985-91. doi: 10.1038/ijo.2008.8. Epub 2008 Feb 12.
• Anderson JW, Randles KM, Kendall CW, Jenkins DJ. Carbohydrate and fiber recommendations for individuals with diabetes: a quantitative assessment and meta-analysis of the evidence. J Am Coll Nutr. 2004 Feb;23(1):5-17. doi: 10.1080/07315724.2004.10719338.
• Guariguata L, Whiting D, Weil C, Unwin N. The International Diabetes Federation diabetes atlas methodology for estimating global and national prevalence of diabetes in adults. Diabetes Res Clin Pract. 2011 Dec;94(3):322-32. doi: 10.1016/j.diabres.2011.10.040. Epub 2011 Nov 17.
• Kris-Etherton P, Eckel RH, Howard BV, St Jeor S, Bazzarre TL; Nutrition Committee Population Science Committee and Clinical Science Committee of the American Heart Association. AHA Science Advisory: Lyon Diet Heart Study. Benefits of a Mediterranean-style, National Cholesterol Education Program/American Heart Association Step I Dietary Pattern on Cardiovascular Disease. Circulation. 2001 Apr 3;103(13):1823-5. doi: 10.1161/01.cir.103.13.1823. No abstract available.
• Jenkins DJ, Wong JM, Kendall CW, Esfahani A, Ng VW, Leong TC, Faulkner DA, Vidgen E, Paul G, Mukherjea R, Krul ES, Singer W. Effect of a 6-month vegan low-carbohydrate ('Eco-Atkins') diet on cardiovascular risk factors and body weight in hyperlipidaemic adults: a randomised controlled trial. BMJ Open. 2014 Feb 5;4(2):e003505. doi: 10.1136/bmjopen-2013-003505.
• Gremaud G, Piguet C, Baumgartner M, Pouteau E, Decarli B, Berger A, Fay LB. Simultaneous assessment of cholesterol absorption and synthesis in humans using on-line gas chromatography/ combustion and gas chromatography/pyrolysis/isotope-ratio mass spectrometry. Rapid Commun Mass Spectrom. 2001;15(14):1207-13. doi: 10.1002/rcm.365.
• Jenkins DJA, Jones PJH, Abdullah MMH, Lamarche B, Faulkner D, Patel D, Sahye-Pudaruth S, Paquette M, Bashyam B, Pichika SC, Kavanagh ME, Patel P, Liang F, Brown R, Zhao T, Phan M, Mathiyalagan G, Tandon S, Vuksan V, Jovanovski E, Sievenpiper JL, Kendall CWC, Leiter LA, Josse RG. Low-carbohydrate vegan diets in diabetes for weight loss and sustainability: a randomized controlled trial. Am J Clin Nutr. 2022 Sep 26:nqac203. doi: 10.1093/ajcn/nqac203. Online ahead of print.

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2014
• Primary Completion (Actual): December 14, 2016
• Study Completion (Actual): March 13, 2017

Study Registration Dates

• First Submitted: September 5, 2014
• First Submitted That Met QC Criteria: September 17, 2014
• First Posted (Estimate): September 19, 2014

Study Record Updates

• Last Update Posted (Actual): September 18, 2018
• Last Update Submitted That Met QC Criteria: September 17, 2018
• Last Verified: September 1, 2018

More Information

Terms related to this study

• Keywords: Diabetes; Weight loss; Glycemic index; Weight loss diet; Low-carbohydrate diet; Cardiovascular disease (CVD) risk; mediterranean type diet; Canola oil
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Endocrine System Diseases; Diabetes Mellitus; Body Weight; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Overweight
• Other Study ID Numbers: REB# 14-086; CFC/Fund 200134/496744 (Other Identifier: Canola Council of Canada)