This project proposal outlines a randomized-controlled trial (RCT) aimed at evaluating the effects of increased fruit and vegetable (F&V) intake on cognitive performance, attention, and mood in Chinese children aged 7-11 years. The increased F&V intake will be achieved by providing a daily healthy breakfast including at least one piece of fruits and one piece of vegetables. The RCT includes a 2-week Lead-In term, 12 week Intervention term and 4-6 week Washout/Follow-Up term, targeting 250 children from the selected schools in Shanghai. The primary objective is to measure cognitive improvement using the Wechsler Intelligence Scale for Children (WISC-IV), while secondary outcomes will assess mood, attention, biomarkers, behavioral changes in dietary choices and the mechanism. The results of this trial may provide critical evidence on the benefits of F&V consumption in children.

1. Intervention Method: The intervention will be implemented through the Healthy Breakfast Plan.

   1. Healthy Breakfast Plan: During the 12-week intervention period, a pre-designed breakfast (including regular breakfast foods with fruits and vegetables) will be delivered daily to the homes of participating children.
   2. Important Considerations:

   i) The Breakfast Plan will include both the intervention group and the control group. The intervention group will receive the intervention meal (having fruits and vegetables), while the control group will receive a control meal (not having fruits and vegetables).

   ii) The nutritional composition of the Healthy Breakfast Plan will be pre-designed by experts from the Department of Nutrition and Food Hygiene at Fudan University to ensure scientific accuracy.

2. Sample Size: The study will include a total of 250 children from the selected schools. Children will be randomly selected from 6 to 8 classes, resulting in approximately 125 children in the trial group and 125 in the control group. Cluster randomization will be applied at the classroom level, ensuring that all children within the same classroom are assigned to the same group. The sample size calculation is based on previous studies of literature using the Wechsler Intelligence Scale for Children (WISC-IV) to assess cognitive function. With assumptions based on existing literature, the study requires at least 150 participants to achieve statistical power. Accounting for a 20% attrition rate, a sample size of 188 is chosen to ensure robustness.

3. Exposure: Biomarkers, specifically vitamin C (ascorbic acid), will be measured from urine samples to monitor the intake of fruits and vegetables. The analysis will be conducted using reverse-phase high-performance liquid chromatography (HPLC) with UV detection or ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS).

4. Quality Control: To ensure accuracy in dietary intake reporting, the study will utilize food frequency questionnaires and 24-hour dietary records. These tools will help monitor and validate the children's fruit and vegetable consumption throughout the intervention period.

5. Ensuring Compliance with Fruit and Vegetable Intake:

   1. Vitamin C Measurement: Urinary vitamin C levels will be measured to verify actual fruit and vegetable intake.
   2. Questionnaires: Supervision of intake will be supported by questionnaires designed to track compliance and dietary habits.
   3. Online Management Software: The study will use online management software to document each aspect of the project, allowing the research team and supervisors to monitor progress in real-time.

6. Data Collection and Assessments:

   (a) Survey Questionnaires: i) Cognition: Evaluated by Wechsler Intelligence Scale for Children (WISC-IV). ii) Mood: Evaluated using the Profile of Mood States (POMS) questionnaire. iii) Attention: Evaluated by the Conners Parent Symptom Questionnaire (PSQ). iv) Physical Activity: Assessed using the International Physical Activity Questionnaire (IPAQ).

   v) Dietary Habits and Preferences: Assessed by Food Frequency Questionnaire (FFQ), 24-hour dietary records, and the food preference questionnaires.

   vi) A computerized food choice/preference task: Behavioral assessment battery. (b) Biological Specimen Collection: i) Urine sample: for measuring vitamin C. ii) Saliva sample: for measuring cortisol. Saliva sample will be collected from a subpopulation as a pilot study.

   iii) Feces: for exploring the gut mechanisms that may modify the neurobehavior effects by increased intake of fruits and vegetables. Feces sample will be collected from a subpopulation as a pilot study.

   (c) Physical Examinations: i) Measurements of height, weight, waist-to-hip ratio, and skinfold thickness will be taken to assess the overall physical health of participants.

   (d) Subgroup of participants i) An exploratory mechanistic neuroimaging substudy in which functional near-infrared spectroscopy (fNIRS) was used during the food choice/preference task to assess cortical activation associated with food-related decision-making.

Inclusion Criteria:

• Children aged 7-11 years.
• Participants must be students enrolled in the selected schools participating in the study.
• Willingness and ability to consume the provided daily breakfast, including one piece of fruit and one piece of vegetable.
• Parents or legal guardians must provide informed consent for participation.
• Balanced preliminary investigation outcomes, especially regarding behaviors related to fruit and vegetable intake, socioeconomic status (SES), and absence of diagnosed diseases that could impact the study.

Exclusion Criteria:

• Known allergies to any fruits, vegetables, or other foods provided in the intervention.
• Diagnosed psychological disorders, diabetes, gastrointestinal diseases, or other conditions that might interfere with cognitive assessments or the ability to participate in the study.
• Children currently participating in other dietary or cognitive intervention studies.
• Inability or unwillingness to comply with study protocols, including dietary requirements and sample collection.