The Combined Effect of Dietary Nitrate and Caloric Restriction on Cognitive and Vascular Function.

Inclusion Criteria: * Participant is able to give written informed consent for their participation in the study. * Healthy. * Non-smoking adults. * Male or female. * Aged 60 to 75 years. * BMI between 25 and 40 kg/m2. Exclusion Criteria: * Systolic BP \> 180mmHg and/or diastolic BP \>110mmHg at the Clinic Screening Visit. * Contraindication for MRI. * Does not have adequate understanding of verbal and written information in English, sufficient to complete an MRI safety screening and to give informed consent. * Any existing or previous medical condition that may affect the study outcomes (i.e., diabetes, kidney dysfunction, malignant cancer, brain surgery, stroke). * Any medical treatment that may affect the study outcomes (i.e., diuretics, anti-acids, organic nitrates, anti-pyschotics or neuro-stimulants). * Evidence of an eating disorder as indicated by the Three-factor eating questionnaire (Eating Attitudes Tests-26). * Blood donation within the last 3 months of the anticipated intervention beginnings. * Having taken part in a research study in the last 3 months involving invasive procedures or an inconvenience allowance. * High-alcohol consumers (≥ 14 units/week for females, and ≥ 22 units/week for males). * Vegetarianism (likely to have very high nitrate intake and food provided during the dietary intervention unsuitable). * Weight change over 3.0kg in the last 2 months (important influence on vascular function).