Post-prandial Effects of Extra Virgin Olive Oil on Endothelial Function in Adults at Risk for Type 2 Diabetes
Condition: Type 2 Diabetes
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional

Summary: 
      Purpose:

      The number of cases of adults with Type 2 diabetes has quadrupled since 1980. This increase
      in the number of cases of diabetes is attributed to changes in dietary patterns, which
      include an increase in the consumption of obesogenic foods such as sugary foods and
      beverages. Patients with diabetes or at risk for diabetes are more likely to develop a
      cardiovascular event. Though glycemic control remains the basis of diabetes care, the
      co-management of atherosclerosis, hypertension and cardiovascular risk reduction, and
      prevention of long-term consequences are also important predictable measures to improve
      survival. The progression from prediabetes to Type 2 diabetes and complications of diabetes
      could be prevented. Lifestyle interventions (i.e., nutrition and physical activity) are the
      cornerstone for the primary prevention of Type 2 diabetes. Healthful eating can also improve
      cardio-metabolic risk factors associated with those at risk for or Type 2 diabetes. Foods
      that are low in fat and calories and high in fiber, with a focus on fruit, vegetables, whole
      grains, and the inclusion of healthful oils in their diets are typically recommended to
      prevent the progression from prediabetes to diabetes and complications of diabetes. Diets
      rich in mono- and polyunsaturated fatty acids have been shown to improve cardio-metabolic
      health in those at risk for or with Type 2 diabetes patients. However, the effect of olive
      oils on endothelial function (a surrogate marker of cardiovascular risk) in adults at risk
      for Type 2 diabetes is controversial. Refined olive oils lack important antioxidants and
      anti-inflammatory properties. Extra virgin olive oils have relatively higher levels of some
      minor phenolic compounds, and more naturally-occurring minerals and vitamins found in olives,
      that are essential to improve cardio-metabolic risk factors in those at risk for or with Type
      2 diabetes. We propose a prospective, randomized, controlled crossover study to assess the
      post-prandial effects of extra virgin olive oil, versus post-prandial effects of a refined
      olive oil, on endothelial function and blood pressure in adults at risk for Type 2 diabetes.

      Specific Aims To assess the post-prandial effect of extra virgin olive oil on endothelial
      function, measured as flow mediated dilatation, in adults at risk for Type 2 diabetes.
      Specifically, to demonstrate at least a 3.5% improvement in endothelial function following
      the consumption of a meal with 50 mL of extra virgin olive oil, compared with a meal with 50
      mL of refined olive oil, in individuals at risk for Type 2 diabetes.

      To assess the post-prandial effect of extra virgin olive oil on blood pressure in adults at
      risk for Type 2 diabetes. Specifically, to demonstrate at least 3 mmHg improvements in
      systolic and diastolic blood pressure after the consumption of a meal with 50 mL of extra
      virgin olive oil compared with a meal with 50 mL of refined olive oil, in individuals at risk
      for Type 2 diabetes.

      Hypotheses Consumption of a meal with extra virgin olive oil compared with a meal with
      refined olive oil will show superior benefits in endothelial function in adults at risk for
      Type 2 diabetes.

      Consumption of a meal with extra virgin olive oil compared with a meal with refined olive oil
      will show better improvement in blood pressure in adults at risk for Type 2 diabetes.
    

Detailed description: 
      Diabetes is a public health problem of epidemic proportions. According to the 2017 National
      Diabetes Statistics Report, 30 million people, or 9.4% of the U.S. population, are estimated
      to have diabetes, of which 23.1 million people are diagnosed. About 84.1 million people, or 1
      in 3 people in the U.S., are estimated to have prediabetes, yet only 1 out 10 people with
      prediabetes is aware that they have this condition. Of those with prediabetes, 15-30% are
      likely to develop Type 2 diabetes within 5 years. The total medical costs and lost work and
      wages for people with diagnosed diabetes is about $245 billion, with the medical costs for
      people with diabetes being twice as high as for those without diabetes. The risk of death in
      individuals with diabetes is more than 50% higher than for adults without diabetes. Type 2
      diabetes accounts for about 90% to 95% of all diagnosed cases of diabetes. Diabetes is the
      seventh leading cause of death in the U.S. Diabetes complications include cardiovascular
      disease (CVD), stroke, hypertension, blindness, kidney disease, nervous system damage, limb
      amputations, and biochemical imbalances that can cause acute life-threatening events. Rates
      of cardiovascular mortality are 2 to 4 times higher among adults with diabetes than among
      those without diabetes.

      Epidemiological and cohort studies show a clear and consistent correlation of hyperglycemia
      with CVD. High glucose activates a pro-atherogenic phenotype in the vessel wall of
      endothelial cells, vascular smooth muscle cells, inflammatory cells, fibroblasts, and
      platelets, leading to a feed-forward atherogenic response. Diets with a low glycemic load
      have been reported to improve serum lipid profiles, reduce C-reactive protein (CRP) levels,
      and aid in weight control. In cross-sectional studies, they have been associated with higher
      levels of high-density lipoprotein cholesterol (HDL-C), with reduced CRP concentrations, and,
      in cohort studies, with decreased risk of developing diabetes and CVD. Insulin resistance may
      also contribute to high blood pressure, increased triglycerides and LDL cholesterol, and
      reduced levels of HDL cholesterol. While glycemic control remains a cornerstone of diabetes
      care, the co-management of hypertension, atherosclerosis, cardiovascular risk reduction, and
      prevention of long-term consequences are also recognized as essential to improve long-term
      survival.

      The cornerstone of the management and prevention of Type 2 diabetes is lifestyle
      intervention. Prior studies have shown an association between improvement in cardio-metabolic
      health and diets rich in olive oils. Low glycemic index foods are typically recommended for
      patients with Type 2 diabetes or at risk for Type 2 diabetes. Extra virgin olive oil is a
      nutrient-dense food with a low glycemic index. It is rich in mono-unsaturated fatty acids
      that are vital to improve cardio-metabolic risk factors in those at risk for Type 2 diabetes.
      Among all the oils, olive oils have a relatively high content of monounsaturated fatty acids.
      Diets rich in mono- and polyunsaturated fatty acids have shown favorable effects on
      cardiovascular health, glycemic control, insulin sensitivity, and lipid profile. All olive
      oils, (inclusive of extra virgin olive oil), have a relatively higher amount of
      monounsaturated fatty acids. While refined olive oils lack important antioxidants and
      anti-inflammatory properties, extra virgin olive oils specifically contains relatively higher
      levels of some minor phenolic compounds, along with more naturally-occurring minerals and
      vitamins found in olives that have favorable effects on cardio-metabolic health. Therefore,
      the inclusion of extra virgin olive oil in the diets of adults at risk for Type 2 diabetes is
      likely to confer better cardio-metabolic health benefits than a refined olive oil. Some oils
      improve, and some impair, endothelial function. Published studies have said both about olive
      oils, probably because the status and caliber of the olive oils was not always specified. We
      therefore propose to differentiate 'good' from 'bad' olive oils, and to show that extra
      virgin olive oils have decisively beneficial effects, while those effects are attenuated or
      lost as the oil is degraded. Specifically, proposed is a randomized crossover controlled
      trial to assess the impact of extra virgin olive oil, as compared with refined olive oil, on
      endothelial function in adults at risk for Type 2 diabetes.
    

Intervention name(s): Extra Virgin Olive Oil; Refined Olive Oil
Intervention type(s): Other; Other
Intervention description(s): Participants will consume a meal prepared with 50 mL extra virgin olive oil. The meals will be prepared and provided to the study participants in the cafeteria of Griffin Hospital, where the Prevention Research Center is located. With the exception of the type of olive oil used in the meals, the meal plan will be comparable in all the intervention phases for the same individual.; Participants will consume a meal prepared with 50 mL refined olive oil in the cafeteria of Griffin Hospital. With the exception of the olive oil used, the meal plan will be comparable in each the intervention phases for the same individual.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: To provide a sound basis for the statistical comparison of outcome measures for treatment assignments, participants will be randomized to 1 of 2 sequence permutations of extra virgin olive oil enriched meal and refined olive oil enriched meal. Each permutation will include a first treatment assignment, followed by a 1-week washout phase, and followed by a second treatment assignment.
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Prevention