Impact of Lowering Phosphate Additive Intake on Metabolism and Cardiovascular Health in Community-Living Adults

Inclusion Criteria: * (i.) Inclusion criteria for healthy volunteers: ≥18 years of age, normal kidney function (eGFR \> 60 and normal urinalysis). Exclusion Criteria: * Exclusion criteria for healthy volunteers will include: * current smoking * extreme obesity (BMI ≥ 35 kg/m2) * pregnancy or breastfeeding * conditions affecting phosphate metabolism (e.g., hyper- or hypothyroidism; irregular menses for menstruating women) * current intake of medications that impact phosphate metabolism (high-dose vitamin D, chronic antacid use) * current use of blood pressure medications * abnormal serum phosphate (≥ 4.6 or \< 2.5 mg/dl) or calcium levels (≥ 10.6 or \< 8.5 mg/dl) * severe anemia (hemoglobin \< 8 g/dl for women and \< 9 g/dl for men). * Inability to receive weekly shipments of food at home. * Requirement for any special diet other than a regular diet. * Allergies to any foods in the standardized diets (ii.) Inclusion criteria for CKD patients: ≥18 years of age, eGFR 20-50 ml/min Exclusion criteria for CKD patients will include: * clinical need for a low potassium, low sodium or low protein diet * new or recent change (\<3 months) in dosage of medications known to impact vascular reactivity * current smoking * poorly controlled hypertension (≥160/100 mmHg) * extreme obesity (BMI ≥ 35 kg/m2) * pregnancy or breastfeeding * conditions affecting phosphate metabolism (e.g., hyper- or hypothyroidism) * current intake of medications that impact phosphate met…