This is a randomized, double-blinded trial (Chardonnay seed flour vs. placebo - in pill form) with the purpose to test the impact of a four-month supplementation with Chardonnay Seed Flour (CSF) on endothelial function. Chardonnay flour is made from wine grape skins and seeds. We will examine the effect of CSF on parameters such as endothelial function (via EndoPAT testing), plasma lipid levels, glucose tolerance, insulin resistance, inflammatory markers, oxidative stress surrogates, endothelial progenitor cells (EPCs) as well as the makeup of and impact on the gut microbiome (via stool samples).

Inclusion Criteria:

1. Age >= 18 years old
2. Demonstrated endothelial dysfunction (EndoPAT score <= 2) at time of screening.

Exclusion criteria:

1. Age below 18 or above 80

2. Endothelial function greater than 2.0 at baseline

3. Hypertension (at screening): any patient with systolic blood pressure (SBP >=170 mmHg or diastolic blood pressure >= 110 mmHg, or hypotension (SBP < 100 mmHg

4. Abnormal liver function tests

5. Uncontrolled Diabetes Mellitus or the use of metformin for Diabetes Mellitus

6. Difficulty swallowing capsules

7. Gastrointestinal disease manifesting with symptoms of malabsorption such as celiac disease or Crohn's disease

8. Non-English speakers

9. Vulnerable populations unable to consent such as prisoners or dependents

10. Any surgical or medical condition which might significantly alter the absorption, distribution, metabolism, or excretion of the CSF including, but not limited to, any of the following:

    1. History of major gastrointestinal tract surgery such as gastrectomy, gastroenterostomy or bowel resection
    2. Any history of pancreatic injury, pancreatitis or evidence of impaired pancreatic function/injury as indicated by abnormal lipase or amylase
    3. Evidence of hepatic disease as determined by a history of hepatic encephalopathy, a history of cirrhosis, esophageal varices, or a history of portocaval shunt.

11. History of hypersensitivity to any of the study supplement or suspected contraindications to the study supplement.

12. History of noncompliance to medical regimens or unwillingness to comply with the study protocol