Effect of Resveratrol and Vitamin C on Insulin Resistance Among Postmenopausal Women

Study Overview
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Brief Summary
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Hormonal and metabolic changes because of postmenopause increase body weight, central abdominal fat, alter lipid profile and insulin resistance, those factors increase the risk up to 60% to develop metabolic syndrome, diabetes and cardiovascular diseases. Because there is no efficient antioxidant therapy in postmenopausal women, this study proposes a therapy with resveratrol and vitamin C to increase the total antioxidant capacity; as well as to decrease insulin resistance and in consequence decreased the risk of diabetes, metabolic syndrome and cardiovascular disease

Detailed Description
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Currently, there are not studies that demonstrate an efficient antioxidant therapy in postmenopausal women, to increase the total antioxidant capacity and to decrease insulin resistance and biochemical parameters of cardio-metabolic risk. Therefore, the aim of this study is to evaluate the effect of the co-administration of resveratrol and vitamin C on insulin resistance and antioxidant capacity by a double-blind randomized clinical trial. A population of 270 postmenopausal women will be studied, stratified into 3 groups: Group 1: Three-month administration of vitamin C 500 mg daily + placebo Group 2: Three-month administration of resveratrol 500 mg daily + placebo Group 3: Three months administration of vitamin C 500 mg daily and resveratrol 500 mg daily as antioxidant therapy. All participants will be monitored monthly for a period of 3 months: glucose, insulin, uric acid, Homeostatic Model Assessment (HOMA), total cholesterol (TC), triglycerides (TGC), High density lipoproteins-cholesterol (HDL- C), low density lipoproteins-cholesterol (LDL), blood pressure, body mass index (BMI). The antioxidant efficiency in erythrocytes by the quantification of antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase), as well as total antioxidant capacity in plasma. In order to corroborate the oxidative damage, the product of the lipoperoxidation malondialdehyde and the carbonylation of proteins will be evaluated by spectrophotometric techniques before and three months after the intervention.

Official Title
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Effect of Resveratrol and Vitamin C on Insulin Resistance and Antioxidant Capacity in Postmenopausal Women. A Randomized Clinical Trial

Conditions
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Postmenopausal, Insulin Resistance

Intervention / Treatment
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* Dietary Supplement: vitamin C (500 mg / day) + placebo
* Dietary Supplement: resveratrol (500 mg / day) + placebo
* Dietary Supplement: vitamin C (500 mg / day) and resveratrol (500 mg / day)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Women diagnosed with early postmenopause according to STRAW classification. Insulin resistance determinated by HOMA ≥ 2.5. Not use of metformin, bezafibrates and / or statins, three months before enter to the study No indication of hormone replacement therapy. Sign the informed consent. Exclusion Criteria: Women who present pathologies such as: Diabetes Mellitus, rheumatoid arthritis, lupus, neoplasms of any type, HIV, or kidney disease during the course of the study. Women who during the development of the protocol require hormone replacement therapy. Any type of surgical intervention during the following of the study. That the patient wishes to withdraw from the study. That the patient does not complete with 80% of adherence to the treatment

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Randomized Clinical Trial
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Group 1<br>vitamin C (500 mg/day/orally) + placebo | Dietary Supplement: vitamin C (500 mg / day) + placebo<br>* Adminstration of vitamin C (500 mg / day/orally) + placebo (same presentation like resveratrol)<br>|
| Placebo Comparator: Group 2<br>resveratrol (500 mg/day/orally) + placebo | Dietary Supplement: resveratrol (500 mg / day) + placebo<br>* Adminstration of resveratrol (500 mg / day/orally) + placebo (same presentation like vitamin C)<br>|
| Active Comparator: Group 3<br>vitamin C (500 mg/day/orally) + resveratrol (500 mg/day/orally) | Dietary Supplement: vitamin C (500 mg / day) and resveratrol (500 mg / day)<br>* Adminstration of resveratrol (500 mg / day/orally) + vitamin C 500 mg/day/orally)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Insulin resistance | Insulin resistance measured by HOMA (Homeostatic Model Assessment) | HOMA at 3 months after starting the intervention in each group | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Superoxide dismutase activity | Enzymatic activity measured by spectrophotometry | three months after starting the intervention | 
| Catalase activity | Enzymatic activity measured by spectrophotometry | three months after starting the intervention | 
| Glutathione peroxidase activity | Enzymatic activity measured by spectrophotometry | three months after starting the intervention | 
| Glutathione reductase activity | Enzymatic activity measured by spectrophotometry | three months after starting the intervention | 
| Malondialdehyde | Enzymatic activity measured by spectrophotometry | three months after starting the intervention | 
| Carbonylation of proteins | Marker of oxidative stress measured by spectrophotometry | three months after starting the intervention | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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resveratrol, vitamin C, antioxidant therapy, antioxidant capacity