Cardiovascular Diseases, Obesity, Overweight, Type 2 Diabetes
Conditions
Keywords
Weight loss, Diabetes, Cardiovascular disease (CVD) risk, Weight loss diet, mediterranean type diet, Canola oil, Low-carbohydrate diet, Glycemic index
Brief summary
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.
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.
Interventions
BEHAVIORALA 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.
BEHAVIORALA 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
Sponsors
University of Toronto
Laval University
University of Manitoba
Canola Council of Canada
Unity Health Toronto
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Investigator)
Eligibility
Sex/Gender
ALL
Age
21 Years to No maximum
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| change in HbA1c | Measured at weeks -2, 0, and then at weeks 8, 10 and 12 | 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 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| 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 | At weeks -1 and 12 | Measurement will be done using a non-invasive SpaceLabs 90217 Ambulatory BP monitor |
| diet history | At weeks 0, 2, 4, 8, 10 and 12 | 7-day food records brought in at weeks 0, 2, 4, 8, 10 and 12 will be analyzed for macro and micro nutrient intakes. |
| C-reactive protein | At weeks 0 and 12 | — |
| Cholesterol absorption | At weeks -1 and 12 | 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. |
| change in LDL particle size | Weeks 0 and 12 | 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 |
| urinary analyses | week 0 and week 12 | 24 hr urine samples will be analyzed for creatinine, urea, C-peptide, minerals, electrolytes and other dietary biomarkers |
Other
| Measure | Time frame | Description |
|---|---|---|
| Satiety | at weeks 0, 2, 4, 8, 10 and 12 | 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. |
| Taste (palatability) of the study diets, breads and other supplements given | At weeks 2, 4, 8, 10 and 12 | 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. |
| The Medical Outcomes Study 36-Item Short Form Questionnaire (SF-36) | At weeks 0 and 12 | Survey on quality of life |
| Genetic whole genome testing | Week 0 or any other time point | One time sample collection of buffy coat (from white cells) for future study on gene, diet and chronic disease relationship. |
| complete blood count (CBC) | Week 0 and week 12 | Health check at start and end of study |
| Renal function test | week 0 and week 12 | Health check at start and end of study |
| Liver function test | week 0 and week 12 | Health check at start and end of study |
| Prostatic specific antigen (PSA) | week 0 and week 12 | Male participants will undergo this test. |
| sustainability of diet | week 10 and week 12 | 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. |
| Testosterone level | week 0 and week 12 | Male participants will undergo this test |
| Estradiol level | week 0 and week 12 | Female participants will undergo this test |
Countries
Canada
Outcome results
None listed