Olive Oil Supplementation for Heart Failure With Reduced Ejection Fraction

Inclusion Criteria: * Diagnosed with HFrEF with left ventricular ejection fraction ≤35 %. * Referred to and enrolled in the standard cardiac rehabilitation program at Sentara Cardiac Rehabilitation Center, but has not yet initiated/started cardiac rehabilitation (i.e., has not attended the first cardiac rehab session). * Able and willing to comply with study procedures and provide informed consent. Exclusion Criteria: * Co-morbidity expected to limit survival (e.g., terminal illness). * End-stage renal disease. * Unstable fluid overload. * Current pregnancy (self-disclose). * Habitual use of EVOO greater than 4 tablespoons per day. * Known allergy or sensitivity to olive oil or its components. * Unwillingness or inability to incorporate EVOO or dietary recommendations.