Cardiovascular disease is the main cause of death worldwide. Endothelial dysfunction is the first step to development of cardiovascular diseases. Endothelial dysfunction occurs due to reduction in nitric oxide, a molecule that plays an important role on vascular health. Due to important role of nitric oxide in endothelial function, several studies have evaluated the effect of its precursors, such as L-citrulline and nitrate on endothelial function parameters. The present study will evaluate the effect of L-citrulline and nitrate derived by watermelon and beetroot products, respectively, on endothelial function of young and older participants. Furthermore, we will evaluate the plasmatic amino acids, nitrate, glucose and insulin in response to ingestion of these products.

Inclusion Criteria for healthy young participants:

• Age between 18-35 years;
• Triglycerides ≤ 150 mg/dL
• HDL-cholesterol ≥ 50 mg/dL for women and ≥ 40 mg/dL for men;
• Waist circumference ≤ 102 cm for men and ≤ 88 cm for women).

Inclusion Criteria for older people with cardiovascular risk:

• Age ≥ 60 years;
• Elevated triglycerides ≥150 mg/dL;
• Reduced HDL-cholesterol ≤ 50 mg/dL for women and ≤ 40 mg/dL for men;
• Elevated waist circumference ≥102 cm for men and ≥ 88 cm for women).

Exclusion Criteria:

• Elevated fasting glucose (≥100 mg/dL);
• Smoking;
• Beetroot or watermelon allergy;
• Unwillingness to avoid beetroot or watermelon products during the entire study;
• Other chronic diseases (diabetes, liver disease, etc.) or acutely ill