Effect of 6-week Strawberry Supplementation on Insulin Action (STR2)

Sponsor

Clinical Nutrition Research Center, Illinois Institute of Technology (Industry)

Overall Status

Active, not recruiting

CT.gov ID

NCT01457612

Collaborator

California Strawberry Commission (Other)

Enrollment

Location

Arms

134

Anticipated Duration (Months)

0.3

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

The primary study objective is to investigate the potential chronic beneficial effect of polyphenolics derived from strawberry on impaired insulin signaling in insulin resistant individuals through their ability to modulate oxidative- and inflammatory-markers that lead to devastating disease, including, but not limited to, diabetes and cardiovascular disease.

Condition or Disease	Intervention/Treatment	Phase
Insulin Resistance Nutritional Disease Metabolic Disease	Dietary Supplement: Strawberry Dietary Supplement: Placebo1 Dietary Supplement: Placebo2	N/A

Detailed Description

This study is a single-center, randomized and single blinded, placebo-controlled, 6-week, parallel design study with follow-up to evaluate strawberry-associated chronic improvements in insulin action resulting in reduced whole body insulin resistance and improved glucose tolerance. This study will take approximately 11~12 weeks.

Subjects will follow an extremely limited polyphenolic diet throughout the duration of their participation in the study.

The limited diet will begin 7 days before the first study visit and end before the last study visit. Following the polyphenol-free 7-day run in period, at Week 0, subjects will be scheduled to return to the Center for sequence randomization, an Oral Glucose Tolerance Test (OGTT) as well as a Flow Mediated Dilation (FMD) procedure to measure endothelial function. Subjects will incorporate either one of tow Placebo Beverages (PBO1, n=15; PBO2, n=15) or Strawberry Beverage (STR, n=15, an optimal strawberry test dose of 40 g/d) into their diet daily for a period of 6 weeks. Subjects will consume randomly assigned beverage twice per day with their breakfast and dinner meals.

All subjects will be asked to come to the Center once a week where they will receive a week's supply of beverages. Additionally, fasting clinical and laboratory variables, anthropometrics, and vital sign measurements will be assessed at each bi-weekly visit at Week 3 and Week 5.

Participants will undergo the same procedures at the end of Week 6: fasting blood sample collection for analysis of insulin, glucose, oxidative and inflammatory markers, an OGTT to assess glucose handling, as well as a FMD procedure to assess endothelial function in response to 6 weeks of either the Placebo or Strawberry treatment.

Subjects will be required to visit the Center 4 weeks after the end of their intervention period (Week 10), at which time they will undergo their last anthropometrics and vital sign measurements, a 4 hour OGTT, and the FMD procedure.

Study Design

Study Type:

Interventional

Actual Enrollment :

45 participants

Allocation:

Randomized

Intervention Model:

Parallel Assignment

Masking:

Single (Participant)

Primary Purpose:

Treatment

Official Title:

Effect of 6 Weeks Strawberry Supplementation on Insulin Action and Associated Risk Factors in Insulin Resistant (IR) Subjects (STR2)

Actual Study Start Date :

Oct 1, 2011

Anticipated Primary Completion Date :

Dec 1, 2022

Anticipated Study Completion Date :

Dec 1, 2022

Arms and Interventions

Arm	Intervention/Treatment
Placebo Comparator: Placebo1 Placebo Beverage 1 without fiber	Dietary Supplement: Placebo1 Placebo Beverage 1 without fiber
Active Comparator: Strawberry Strawberry Beverage 20g/BID	Dietary Supplement: Strawberry 20g twice per day (BID) in beverage
Placebo Comparator: Placebo2 Placebo Beverage 2 with Fiber	Dietary Supplement: Placebo2 Placebo Beverage 2 with Fiber

Arm

Intervention/Treatment

Placebo Comparator: Placebo1

Placebo Beverage 1 without fiber

Dietary Supplement: Placebo1

Placebo Beverage 1 without fiber

Active Comparator: Strawberry

Strawberry Beverage 20g/BID

Dietary Supplement: Strawberry

20g twice per day (BID) in beverage

Placebo Comparator: Placebo2

Placebo Beverage 2 with Fiber

Dietary Supplement: Placebo2

Placebo Beverage 2 with Fiber

Outcome Measures

Primary Outcome Measures

The chronic beneficial effect of polyphenolics from strawberry on impaired insulin signaling in insulin-resistant men and women [10 weeks]
Subjects will be randomized to receive either one of beverages, Pbo1, Pbo2 or Str Beverage and consume randomly assigned beverage twice per day with their breakfast and dinner meals for 6 weeks. On visits at Wk0, Wk6, and Wk10, blood will be collected at 0h, and 1h, 2h, 3h and 4h time points following the 75 g glucose load (oral glucose tolerance test) and Flow Mediated Dilation (FMD) procedure will be performed as well.

Secondary Outcome Measures

The chronic beneficial effect of polyphenolics from strawberry on oxidative- and inflammatory-markers in insulin-resistant men and women [10 Weeks]
Samples of venous blood will be collected for measurement of oxidative and inflammatory markers (hs-CRP levels, LDL oxidation, Interleukin (IL)-6 and other inflammatory molecules, Total antioxidant levels of the blood)

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years to 65 Years

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Inclusion Criteria:

Must meet ONE or MORE of the criteria (1)-(5) associated with insulin resistance along with all other criteria listed (6)-(9):

Blood glucose concentration between140-199 mg/dL at 2hr from OGTT.
Elevated fasting glucose (110 mg/dL≤ Fasting blood glucose <126 mg/dL)
Elevated fasting insulin (>75th percentile cutoff of 13.13 μU/mL)
Insulin resistance defined by the homeostasis model assessment method of insulin resistance (HOMA-IR) (glucose [in millimoles per liter] × insulin [in microunits per milliliter]/22.5) values of at least 2.5.
Waist circumference ≥ 110 cm because many epidemiology studies have been shown that waist circumferences may be related to insulin resistance.
Nonsmokers
Not taking any medications that would interfere with outcomes of the study, i.e. lipid lowering medications, anti-inflammatory drugs, or dietary supplements
18 years of age and older
No clinical evidence of cardiovascular, metabolic, respiratory, renal, gastrointestinal or hepatic disease

Exclusion Criteria:

Pregnant and/or lactating.
Allergy or intolerance to strawberries and dairy products.
Current regular consumption of strawberries is > 2 servings per day.
Fasting blood glucose ≥ 126 mg/dL. Subjects identified with elevated fasting blood glucose levels will be advised to contact their primary care physician for appropriate follow-up care.
Taking over the counter antioxidant supplements or other supplements that may interfere with the study procedures or endpoints.
Subjects with unusual dietary habits (e.g. pica).
Actively losing weight or trying to lose weight (unstable body weight fluctuations of > 5 kg in a 60 day period).
Excessive exercisers or trained athletes.
Subjects with documented atherosclerotic disease, inflammatory disease, diabetes mellitus, or other systemic diseases.
Addicted to drugs and/or alcohol.
Medically documented psychiatric or neurological disturbances.
Smoker (past smoker may be allowed if cessation is > 2 years).

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Clinical Nutrition Research Center	Chicago	Illinois	United States	60616

Sponsors and Collaborators

Clinical Nutrition Research Center, Illinois Institute of Technology
California Strawberry Commission

Investigators

Principal Investigator: Indika Edirisinghe, Ph.D, Institute for Food Safety and Health
Principal Investigator: Britt Burton-Freeman, Ph.D, Institute for Food Safety and Health