Effects of Walnut Consumption on Endothelial Function in Type 2 Diabetes

NCT ID: NCT00901043

Last Updated: 2020-03-26

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 24 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2007-10-31
• Study Completion Date: 2008-09-30

Brief Summary

The purpose of this study is to examine the effects of sustained walnut consumption on endothelial function and lipid markers in patients with Type 2 diabetes mellitus.

Detailed Description

Evidence-based guidelines for the management of type 2 diabetes mellitus and related cardiovascular disease (CVD) refer to cardioprotective dietary fatty acid proportions. Several studies demonstrate the hypocholesteremic effects of walnuts in energy restricted diets. To our knowledge, the health benefits accrued as a result of addition of walnuts to an ad libitum diet in type 2 diabetic subjects have not been studied. Addition of walnuts to an ad libitum diet represents a practical way to achieve the recommended fatty acid proportions. The proposed study will examine whether a total dietary pattern inclusive of walnuts, will result in amelioration of cardiac risk as measured by improvement in endothelial function and glycemic control in type 2 diabetics. Results of the study will have important implications for clinicians and dietitians in dietary management of type 2 diabetes. Demonstrating that walnuts can be regarded as beneficial components of dietary management of type 2 diabetes is of relevance to the walnut industry as well. The study employs a pragmatic approach to approximate dietary practices in a real world setting thus enhancing the external validity of the study. If positive, the study results can inform future marketing efforts of the California Walnut Commission. Demonstrating that addition of walnuts to an ad libitum diet can potentially lead to improvement in endothelial function, improve lipid profiles, glycemic control and reduce the risk of CVD complications in diabetic patients has important applications for dietary management of diabetes.

Conditions

DIABETES MELLITUS TYPE 2

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

Walnut supplementation

Eight weeks with walnut supplementation to an ad lib diet

Group Type: EXPERIMENTAL

Walnut supplementation

Intervention Type: DIETARY_SUPPLEMENT

Eight weeks of walnut supplementation

Ad lib diet

Eight weeks ad lib diet without walnut supplementation

Group Type: ACTIVE_COMPARATOR

Ad lib diet

Intervention Type: DIETARY_SUPPLEMENT

Eight weeks without walnut supplementation

Interventions

Walnut supplementation

Eight weeks of walnut supplementation

Intervention Type: DIETARY_SUPPLEMENT

Ad lib diet

Eight weeks without walnut supplementation

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

Inclusion Criteria

1. men and women ages 35-75

2. non-smoker

3. able to have blood pressure taken bilaterally

4. diagnosed with type 2 diabetes by physician for at least one year

5. stable glucose levels and medication dose for the past 3 months

6. not on insulin therapy

2. anticipated inability to complete or comply with study protocol for any reason (e.g., inability to communicate in English, dementia) or any unstable medical condition that would limit the ability of a subject to participate fully in the trial (e.g., wasting illness, AIDS, tuberculosis, psychotic disorder)

3. diagnosed eating disorder

4. use of lipid-lowering or antihypertensive medications (statins, red rice yeast extract, garlic) unless stable on medication for at least 3 months and willing to refrain from taking medication for 12 hours prior to endothelial function (EF) scanning, vasoactive medication (i.e., glucocorticoids, antineoplastic agents, psychoactive agents, or bronchodilators) or nutriceuticals

5. regular use of multivitamins and/or complementary or alternative supplement therapy and unwillingness to discontinue supplementation for at least 8 weeks prior to study initiation and for study duration

6. any rheumatologic disease requiring regular use of nonsteroidal antiinflammatory drug (NSAIDs) or alternative medications

7. regular use of fiber supplements

8. preexisting cardiovascular disease, including symptomatic coronary artery disease (CAD), myocardial infarction, angina pectoris, anginal equivalent, peripheral vascular disease (claudication, amputation, or revascularization) congestive heart failure, carotid stenosis, aortic stenosis or stroke; diabetes, sleep apnea, severe uncontrolled hypertension (systolic blood pressure > 180 mmHg or diastolic blood pressure > 105 mmHg)

9. coagulopathy, known bleeding diathesis or history of clinically significant hemorrhage; current use of warfarin

10. clinically significant anemia (Hct < 36% in men, < 33% in women)

11. intestinal or stomach disease

12. inability to use right or left arm for endothelial function testing for any reason such as breast surgery, trauma, radiation to right axilla, lymphedema, right arm shunt, severe vascular disease in right arm

13. subjects on a disease specific diet

14. subjects on a weight control diet

15. subjects on a vegan diet

16. allergy to any kind of nut, including walnuts and peanuts

• Minimum Eligible Age: 35 Years
• Maximum Eligible Age: 75 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

California Walnut Commission

OTHER

Sponsor Role: collaborator

Griffin Hospital

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

DAVID L KATZ, MD

Role: PRINCIPAL_INVESTIGATOR

Yale-Griffin Prevention Research Center

Locations

Griffin Hospital

Derby, Connecticut, United States

Countries

United States

Other Identifiers

2007-10

Identifier Type: -

Identifier Source: org_study_id