Western Diet on Cardiometabolic and Immune Function

Inclusion Criteria: * ability to provide informed consent * men and postmenopausal women aged 50-64 years * systolic blood pressure \< 130 mmHg; diastolic blood pressure \< 90 mmHg * body mass index (BMI) \<30 kg/m2 and % body fat \< 25% for men and \< 33% for women * fasting triglycerides \< 200 mg/dl (\< 2.3 mmol/L) * low density lipoprotein (LDL) cholesterol \<160 mg/dl (4.14 mmol/L) * fasting plasma glucose \<126 mg/dl (\<7.0 mmol/L) * weight stable in the prior 6 months (≤ 2 kg weight change) * blood chemistries indicative of normal liver enzymes and renal function (estimated glomerular filtration rate using the Modification of Diet in Renal Disease (MDRD) prediction equation must be \>60 ml/min/1.73 m\^2) Exclusion Criteria: * current use of medications or supplements known to lower blood triglycerides or cholesterol (e.g., fibrates, statins, high dose niacin, high dose omega-3 supplement) * chronic clinical diseases (e.g., coronary artery/peripheral artery/cerebrovascular diseases, heart failure, diabetes, chronic kidney disease requiring dialysis, neurological or autoimmune conditions affecting cognition (e.g. Alzheimer's disease or other forms of dementia, Parkinson's disease, epilepsy, multiple sclerosis, large vessel infarct) * major psychiatric disorder (e.g. schizophrenia, bipolar disorder) * current or past (i.e., last 3 months) use of anti-hypertensive or other cardiovascular-acting medications known to influence vascular function and/or arterial stiffness * current medication use likely to affect central nervous system (CNS) functions (e.g. long active benzodiazepines) * concussion within last 2 years and ≥ 3 lifetime concussions * heavy alcohol consumption (≥8 drinks/week for women and ≥15 drinks/week for men) * recent major change in health status within the previous 6 months (i.e., surgery, significant infection, or illness) * current smoking within the past 3 months.